Patent Publication Number: US-2022235080-A1

Title: Selective detection of bed bugs

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 17/295,316, filed on May 19, 2021, which is a national stage filing under 35 U.S.C. § 371(c) of International Application Serial No. PCT/US19/62423, filed on Nov. 20, 2019, which claims the benefit of U.S. Provisional Patent Application No. 62/770,413, filed on Nov. 21, 2018, the entirety of each of which is incorporated herein by reference. 
     Cross reference is made to U.S. application Ser. No. 15/985,093, filed May 21, 2018, and International Application Serial No. PCT/US2018/033679, filed May 21, 2018. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to pest control, and more particularly, to the detection, monitoring, and control of insects, including for example, bed bugs. 
     BACKGROUND 
     Recent data suggests bed bug infestations ( Cimex  species) of human domiciles are on the rise. At least 92 species have been identified globally, of which at least 16 species are in the North American continent. Generally, bed bugs are parasitic pests with hosts including humans and various domesticated animals. It is believed that bed bug infestations are becoming more problematic now at least in part because long acting, residual insecticides are no longer being used to keep bed bug populations in check. In addition, increased international travel and insecticide resistance have made bed bug infestations spread and control with insecticides very difficult. In terms of scale, such infestations are of particular concern for hoteliers, cruise ships, trains, daycare facilities, and the like because of the business reputation risk posed by bad press or bad reviews. Other problematic areas tend to include nursing homes, barracks, dorms, hospitals, and various other forms of high density housing. Nonetheless, single family homes can likewise be impacted adversely. 
     An exemplary bed bug behavioral study is described in Corraine A. McNeill et al.,  Journal Of Medical Entomology,  2016 Jul. 1. 53(4):760-769, which is hereby incorporated by reference in its entirety. Exemplary studies about bed bug mating behavior and pheromone are described in Vincent Harraca et al.,  BMC Biology.  2010 Sep. 9; 8:121 and Joelle F Olson et al.,  Pest Management Science,  2017 January; 73(1): 198-205, each of which is hereby incorporated by reference in its entirety. Suitable sampling and pre-concentration techniques are described in Maria Rosa Ras et al.,  Trac Trends In Analytical Chemistry,  2009 Mar. 28(3): 347-361, which is hereby incorporated by reference in its entirety. Exemplary antibody detection methods for bed bugs are described in U.S. Pat. No. 9,500,643 and U.S. Pat. App. No. 2017/0137501, each of which is hereby incorporated by reference in its entirety. An exemplary detection system based on image analysis is described in U.S. Pat. No. 9,664,813, which is hereby incorporated by reference in its entirety. 
     SUMMARY 
     According to one aspect of the disclosure, a pest control device is disclosed. The pest control device comprises a sensor that includes a sensor cell and a controller coupled to the sensor. A surface of the sensor cell is coated with an agent that reacts with a targeted biochemical analyte secreted by pests. The controller is configured to receive sensor data from the sensor cell indicative of a rate of change in sensor mass detected on the surface of the sensor cell, determine whether the rate of change in the sensor mass based on the received sensor data exceeds a predefined threshold rate, and transmit a pest detection alert notification to a server in response to a determination that the rate of change exceeds the predetermined threshold rate. The rate of change correlates to an increase in the concentration of the targeted biochemical analyte. 
     In some embodiments, the pest control device may include a handle that provides a grip for a human operator to move the pest control device to identify a localized area of the targeted biochemical analyte. 
     In some embodiments, the controller may be further configured to activate a timer when the rate of change exceeds a predefined threshold rate, deactivate the timer when the rate of change returns to less than the predefined threshold rate, determine an amount of time that the rate of change in the sensor mass exceeded the predefined threshold rate, and determine whether the amount of time is greater than a predefined time period. 
     In some embodiments, the controller may transmit a pest detection alert notification in response to a determination that the amount of time is greater than the predefined time period. 
     In some embodiments, the predefined threshold rate may be a base mass change rate in the presence of bed bugs. 
     In some embodiments, the targeted biochemical analyte may include an analyte found in secretion of bed bugs. For example, in some embodiments, the targeted biochemical analyte may include trans-2-hexenal (T2H). Additionally or alternatively, in some embodiments, the targeted biochemical analyte may include trans-2-octenal (T2O). In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-hexenal. In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-octenal. 
     In some embodiments, the agent may include dioctyl cyclic thiol intermediate (dioctyl-CTI). Additionally or alternatively, in some embodiments, the agent may include cyclic thiol intermediate (CTI). 
     In some embodiments, the sensor may be a quartz crystal microbalance. In some embodiments, the sensor cell may be a quartz crystal resonator. 
     According to another aspect, a method of detecting a presence of pests is disclosed. The method includes receiving data indicative of a sensor mass rate of change from a sensor, determining whether the sensor mass rate of change exceeds a predefined threshold rate, and transmitting a pest detection alert notification to a server in response to a determination that the rate of change exceeds the predetermined threshold rate. The sensor includes a coating that reacts with a targeted biochemical analyte secreted by pests, and the sensor mass rate of change correlates to an increase in a concentration of a targeted biochemical analyte. 
     In some embodiments, the method may include activating a timer when the rate of change exceeds a predefined threshold rate, deactivating the timer when the rate of change returns to less than the predefined threshold rate, determining an amount of time that the rate of change in the sensor mass exceeded the predefined threshold rate, and determining whether the amount of time is greater than a predefined time period. 
     In some embodiments, transmitting the pest detection alert notification may include transmitting a pest detection alert notification in response to a determination that the amount of time is greater than the predefined time period. 
     In some embodiments, the predefined threshold rate may be a base mass change rate in the presence of bed bugs. 
     In some embodiments, the targeted biochemical analyte may include trans-2-hexenal (T2H). Additionally or alternatively, in some embodiments, the targeted biochemical analyte may include trans-2-octenal (T2O). In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-hexenal. In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-octenal. 
     In some embodiments, the coating may include dioctyl cyclic thiol intermediate (dioctyl-CTI). Additionally or alternatively, in some embodiments, the coating may include cyclic thiol intermediate (CTI). 
     In some embodiments, the sensor may be a quartz crystal microbalance. 
     In some embodiments, the surface of the sensor cell may be coated with a coating gel compound that includes a polymer gel and the agent. 
     In some embodiments, the polymer gel may have high viscosity and high thermal and chemical stability to form a stable coating on the surface of the sensor cell. In some embodiments, the polymer gel may have a low molecular weight. 
     In some embodiments, the polymer gel may be at least one of polymethylphenylsiloxiane (PMPS), polydimethylsiloxane (PDMS), fluoroalcohol polycarbosilane, fluoroalcohol polysiloxane, bisphenol-containing polymer (BSP3), poly-2-dimethylamin-ethyl-methacrylate (PDMAEMC), and polymers with silicone (Si) and iron (F). 
     In some embodiments, the polymer gel may be polymethylphenylsiloxiane (PMPS). Alternatively, in some embodiments, the polymer gel may be polydimethylsiloxane (PDMS). Alternatively, in some embodiments, the polymer gel may be fluoroalcohol polycarbosilane. Alternatively, in some embodiments, the polymer gel may be fluoroalcohol polysiloxane. Alternatively, in some embodiments, the polymer gel may be bisphenol-containing polymer (BSP3). Alternatively, in some embodiments, the polymer gel may be poly-2-dimethylamin-ethyl-methacrylate (PDMAEMC). Alternatively, in some embodiments, the polymer gel may be polymers with silicone (Si) and iron (F). 
     According to another aspect, a method of detecting a presence of pests is disclosed. The method includes receiving first sensor data from a sensor, receiving second sensor data from the sensor, determining a first slope of signal change based on the first and second sensor data, receiving third sensor data from the sensor, determining a second slope of signal change based on the second and third sensor data, determining if the second slope is different from the first slope, and transmitting a pest detection alert notification to a server in response to a determination that the second slope is different from the first slope. The sensor includes a coating that reacts with a targeted biochemical analyte secreted by pests, and the signal change correlates to an increase in a concentration of a targeted biochemical analyte. 
     In some embodiments, the method further includes activating a timer when the second slope is different from the first slope, receiving sensor data from the sensor and determining a slope of signal change based on the sensor data while the timer is active, deactivating the timer upon detecting no change in slope, determining a time interval measured by the timer, and determining whether the time interval is greater than a predefined time period. In some embodiments, transmitting the pest detection alert notification comprises transmitting a pest detection alert notification in response to a determination that the time interval is greater than the predefined time period. 
     In some embodiments, the predefined threshold rate may be a base mass change rate in the presence of bed bugs. 
     In some embodiments, the targeted biochemical analyte may include trans-2-hexenal (T2H). Additionally or alternatively, in some embodiments, the targeted biochemical analyte may include trans-2-octenal (T2O). In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-hexenal. In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-octenal. 
     In some embodiments, the coating may include dioctyl cyclic thiol intermediate (dioctyl-CTI). Additionally or alternatively, in some embodiments, the coating may include cyclic thiol intermediate (CTI). 
     In some embodiments, the sensor may be a quartz crystal microbalance. 
     In some embodiments, the coating includes a polymer gel and dioctyl cyclic thiol intermediate (dioctyl-CTI) or cyclic thiol intermediate (CTI). 
     In some embodiments, the polymer gel may have high viscosity and high thermal and chemical stability to form a stable coating on the surface of the sensor cell. In some embodiments, the polymer gel may have a low molecular weight. 
     In some embodiments, the polymer gel may be at least one of polymethylphenylsiloxiane (PMPS), polydimethylsiloxane (PDMS), fluoroalcohol polycarbosilane, fluoroalcohol polysiloxane, bisphenol-containing polymer (BSP3), poly-2-dimethylamin-ethyl-methacrylate (PDMAEMC), and polymers with silicone (Si) and iron (F). 
     In some embodiments, the polymer gel may be polymethylphenylsiloxiane (PMPS). Alternatively, in some embodiments, the polymer gel may be polydimethylsiloxane (PDMS). Alternatively, in some embodiments, the polymer gel may be fluoroalcohol polycarbosilane. Alternatively, in some embodiments, the polymer gel may be fluoroalcohol polysiloxane. Alternatively, in some embodiments, the polymer gel may be bisphenol-containing polymer (BSP3). Alternatively, in some embodiments, the polymer gel may be poly-2-dimethylamin-ethyl-methacrylate (PDMAEMC). Alternatively, in some embodiments, the polymer gel may be polymers with silicone (Si) and iron (F). 
     According to another aspect, a method includes determining an amount of agent available on a pest detection sensor to react with a targeted biochemical analyte secreted by pests, determining whether the amount of agent is below a threshold level, and transmitting a notification to a server indicating that the sensor requires a maintenance in response to a determination that the amount of agent is below the threshold level. An amount of the agent coated on the pest detection sensor decreases as the agent reacts with the targeted biochemical analyte. 
     In some embodiments, the agent may include dioctyl cyclic thiol intermediate (dioctyl-CTI). Additionally or alternatively, in some embodiments, the agent may include cyclic thiol intermediate (CTI). 
     In some embodiments, the targeted biochemical analyte may include an analyte found in secretion of bed bugs. For example, the targeted biochemical analyte may include trans-2-hexenal (T2H). Additionally or alternatively, in some embodiments, the targeted biochemical analyte may include trans-2-octenal (T2O). In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-hexenal. In some embodiments, the targeted biochemical analyte may include 4-oxo-(E)-2-octenal. 
     In some embodiments, the threshold level is determined based on a minimum amount of agent required to react with the targeted biochemical analyte. 
     According to another aspect, a cyclic thiol of the formula I 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof is disclosed, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of hydrogen, C 3 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 3 , R 3′ , R 4 , and R 4′  are each independently selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, and C 6 -C 10  aryl; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     In some embodiments, X may be S. In some embodiments, Z 1  may be O. In some embodiments, Z 1  and Z 2  may each be O. In some embodiments, X may be S, and Z 1  and Z 2  may each be O. 
     In some embodiments, R 1  and R 2  may each be C 4 -C 10  alkyl and may be the same. For example, in some embodiments, R 1  and R 2  may each be octyl. 
     Additionally or alternatively, in some embodiments, at least one of R 1  and R 2  may be coupled to the polymeric bulking group. In some embodiments, at least one of R 1  and R 2  may be hydrogen. 
     In some embodiments, the polymeric bulking group may be selected from the group consisting of a silicone, a polyolefin, a polyamide, a polyester, a polycarbonate, a polyaramide, a polyurethane, a polystyrene, an epoxy, a rubber, a starch, a protein, a cellulose, an acrylate, an ABS polymer, a PEEK polymer, a polyol, polyether, polyetherpolyol, and a copolymer of two or more of the foregoing. For example, in some embodiments, the polymeric bulking group may be a silsesquioxane. In some embodiments, the polymeric bulking group may be crosslinked. 
     In some embodiments, le may be of the formula CH 2 O(CH 2 ) 3 S(CH 2 ) 3 R 5 . 
     In some embodiments, the cyclic thiol may have a weight of about 350 Da to about 5000 Da. 
     In some embodiments, a may be 1. 
     In some embodiments, R 3 , R 3′ , R 4 , and R 4′  may each be hydrogen. 
     In some embodiments, the cyclic thiol may be of the formula 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  may each independently be hexyl or octyl. For example, in some embodiments, le and R 2  may each be octyl. 
     In some embodiments, the thiol group may have a pKa of about 1 to about 4. 
     According to another aspect, a cyclic adduct of the formula II 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof is disclosed, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 3 , R 3′ , R 4 , and R 4′  are each independently selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, and C 6 -C 10  aryl; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     R 6  is C 1 -C 12  alkyl or oxo substituted C 1 -C 12  alkyl; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     In some embodiments, R 6  may be propyl or pentyl. For example, in some embodiments, R 6  may be pentyl. In some embodiments, R 6  may be 1-oxopropyl or 1-oxopentyl. 
     According to another aspect, a thiol of the formula III 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof is disclosed, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of C 3 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     According to another aspect, an adduct of the formula IV 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof is disclosed, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     R 6  is C 1 -C 12  alkyl or oxo substituted C 1 -C 12  alkyl; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     According to another aspect, an adduct of the formula V 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof is disclosed, wherein 
     X is S or O; 
     Z 3  and Z 4  are each independently O or S; 
     R 7  and R 8  are each independently selected from the group consisting of C 1 -C 4  alkylene-O—(C 1 -C 4  alkylene) q R 9  and C 1 -C 4  alkylene-S—(C 1 -C 4  alkylene) z R 10 ; 
     R 9  and R 10  are each independently selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; and 
     q and z are each independently an integer from 0 to 10. 
     In some embodiments, each of R 7  and R 8  may be C 1 -C 4  alkylene-O—(C 1 -C 4  alkylene) q R 9 . For example, in some embodiments, each of R 7  and R 8  may be C 2  alkylene-O—(C 1 -C 4  alkylene) q R 9    
     In some embodiments, each of R 7  and R 8  may be C 1 -C 4  alkylene-O—(C 1 -C 4  alkylene) q R 9  and q may be zero. For example, in some embodiments, each of R 7  and R 8  may be C 2  alkylene-O—R 9 . 
     In some embodiments, each of R 7  and R 8  may be C 1 -C 4  alkylene-O—(C 1 -C 4  alkylene) q R 9 , q may be zero, and R 9  may be C 1 -C 8  alkyl. For example, in some embodiments, each of R 7  and R 8  may be CH 2 —CH 2 —O—CH 3 . 
     According to another aspect, a pest control device includes a housing including an inner chamber, a plurality of inlets opening into the inner chamber, and a plurality of inner walls dividing the inner chamber into a plurality of channels. Each channel is sized to receive one or more pests. The pest control device includes any sensor shown and/or described in this application and any controller shown and/or described in this application. The sensor is attached to the housing. 
     In some embodiments, the pest control device may further include an airflow device configured to produce an airflow to draw air along the plurality of channels from the inner chamber to the sensor. 
     In some embodiments, the housing may include a first panel moveable relative to a second panel to permit access to the inner chamber. 
     In some embodiments, the first panel may be pivotally coupled to the second panel. 
     In some embodiments, the housing may include an impermeable liner between an outer frame of the first panel and an outer frame of a second panel to minimize a loss of a targeted biochemical analyte through a gap between the outer frames. 
     In some embodiments, the impermeable liner may be an aluminized film. 
     In some embodiments, the first panel may include a base surface and the plurality of inner walls extend from the base surface. 
     In some embodiments, the first panel may include a ramp surface positioned outside of each inlet to guide pests into the corresponding inlet. 
     In some embodiments, the plurality of inner walls may include a pair of guide walls positioned on each side of an inlet and a barrier wall. Each guide wall may extend in a first direction and define a first channel of the plurality of channels. The barrier wall may be spaced apart from the ends of the guide walls and extend in a second direction orthogonal to the first direction. 
     In some embodiments, the barrier wall may include a first wall section extending in the second direction orthogonal to the first direction, a second wall section extending from an end of the first wall section, and a third wall section extending from an opposite end of the first wall section. The second wall section may extend parallel to the guide walls and cooperate to define a second channel of the plurality of channels. The second wall section may extend parallel to the guide walls and cooperate to define a third channel of the plurality of channels. 
     In some embodiments, the first channel may be configured to direct the airflow in the first direction, and the second and third channels may be configured to direct the airflow in a third direction opposite the first direction. 
     In some embodiments, the barrier wall may be a first barrier wall, and the plurality of inner walls may include a second barrier wall spaced apart from the end of the first barrier wall. The first barrier wall and the second barrier wall may cooperate to define a fourth channel configured to direct airflow in the first direction. 
     In some embodiments, the fourth channel may be offset from the inlets of housing. 
     In some embodiments, the sensor may be positioned in the inner chamber of the housing. 
     In some embodiments, the airflow device may be positioned in the inner chamber. 
     In some embodiments, the pest control device may further include an external pre-concentrator. 
     In some embodiments, the pre-concentrator may include a heating element to increase temperature in the inner chamber. 
     In some embodiments, the pre-concentrator may include a sheet that sorbs a targeted biochemical analyte. 
     In some embodiments, the sheet may be made of a woven or non-woven fibrous material and include sorbent powder between fibers of a sheet of fibrous material. 
     In some embodiments, the pre-concentrator may include multiple sheets made of a woven or non-woven fibrous material that sorb a targeted biochemical analyte and include sorbent powder between two sheets of a fibrous material. 
     In some embodiments, the pre-concentrator may include a tube that extends from an inlet of the plurality of inlets to the sensor and sorbs a targeted biochemical analyte. 
     In some embodiments, the pre-concentrator may include a test chamber sized to receive an amount of a targeted biochemical analyte. 
     In some embodiments, the pre-concentrator may include a surface configured to sorb a targeted biochemical analyte at a first temperature and release the targeted biochemical analyte at a second temperature. 
     In some embodiments, the pest control device may further include a heating element operable to selectively adjust temperature in the inner chamber. 
     In some embodiments, the heating element may be operable increase the temperature to exterminate pests in the inner chamber. 
     In some embodiments, the housing may be configured to be secured to a bed. 
     In some embodiments, the pest control device may further include a headboard of a bed, and the housing is configured to be secured to the headboard of the bed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description particularly refers to the following figures, in which: 
         FIG. 1  is a diagrammatic view of at least one embodiment of a pest control system that includes a plurality of pest control devices; 
         FIG. 2  is a diagrammatic view of at least one embodiment of a pest control device that can be included in the pest control system of  FIG. 1 ; 
         FIG. 3  is a perspective view of at least one embodiment of a detection sensor of a pest control device that can be included in the pest control device of  FIG. 2 ; 
         FIG. 4  is a diagrammatic view of at least one embodiment of a gateway of the pest control system of  FIG. 1 ; 
         FIG. 5  is a simplified flow chart of a control routine of the pest control system of  FIG. 1 ; 
         FIGS. 6 and 7  are simplified flow charts of a first embodiment of a control routine of the pest control system of  FIG. 1 ; 
         FIGS. 8A and 8B  are simplified flow charts of a second embodiment of a control routine of the pest control system of  FIG. 1 ; 
         FIG. 9  is an elevation view of an another embodiment of a pest control device attached to a headboard of a bed; 
         FIG. 10  is a top plan view of the pest control device of  FIG. 9  in an open configuration; 
         FIG. 11  is a perspective view of the pest control device of  FIG. 9 ; 
         FIG. 12  is a top plan view of the pest control device of  FIG. 9  in a closed position; 
         FIG. 13  is a perspective view of an inlet opening of the pest control device of  FIG. 9 ; and 
         FIG. 14  is a cross-sectional view of at least one embodiment of a detection sensor of a pest control device that includes a sensor cell and a sensor coating coated on the surface of the sensor cell, wherein the sensor coating includes a coating gel compound made of a polymer gel and an agent that detects an analyte found in secretion bed bugs; 
         FIG. 15  is a graphical view that illustrates a mass change of polydimethylsiloxane (PDMS) coating gel compound caused by reactions between an agent in the PDMS coating gel compound and the targeted biochemical analyte present in the air surrounding the PDMS polymer gel; and 
         FIG. 16  is a graphical view that illustrates a mass change of polymethylphenylsiloxiane (PMPS) coating gel compound caused by reactions between an agent in the PMPS coating gel compound and the targeted biochemical analyte present in the air surrounding the PMPS polymer gel. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     Referring now to  FIG. 1 , a pest control system  100  for detecting a presence of pests is shown. The system  100  illustratively includes one or more pest control device groups  102  that communicate with a central pest data management server  104  via a network  106 . The central pest data management server  104  is further configured to communicate with one or more client compute device  108  via a network  110  to transmit information received from the pest control device group  102 . 
     The pest control device group  102  includes a plurality of pest control devices  108 . Each pest control device  108  is configured to detect a presence of bed bugs and provides sensor data indicative of the detection of the bed bugs, as described in more detail below. The pest control device  108  transmits the sensor data to the central pest data management server  104  via the network  106 . To do so, in the illustrative embodiment, the plurality of pest control devices  120  communicates with a gateway  122  to transmit sensor data to the network  106 . It should be appreciated that in other embodiments or in other pest control groups  102 , one or more of the control devices  120  may communicate directly with the network  106 . 
     The gateway  122  may be embodied as any type of computation or computer device capable of wirelessly communicating with the pest control device  120  and the network  106 . In some embodiments, a range extender or repeaters may be used to extend a range of communications between the pest control device  102  and the gateway  122 . Additionally, the gateway  122  may incorporate a two-way transceiver for communicating with the pest control device  120  and/or repeaters and the network  106 . In the illustrative embodiment, the gateway device may incorporate digital cellular technology to permit it to communicate with the network  106 . An exemplary system of repeaters and gateway devices is shown and described in U.S. Pat. No. 8,026,822, which issued Sep. 8, 2009 and is expressly incorporated herein by reference. 
     The network  106  may be embodied as any type of network capable of facilitating communications between the gateway  122  of the pest control device group  120  and the central pest data management server  104 . In the illustrative embodiment, the network  106  may be embodied as a cellular network or a wireless wide area network (WAN) using the cellular network. It should be appreciated that, in some embodiments, the network  106  may be embodied as, or otherwise include, a wireless local area network (LAN), a wide area network (WAN), and/or a publicly-accessible, global network such as the Internet. As such, the network  106  may include any number of additional devices, such as additional computers, routers, and switches, to facilitate communications thereacross. In other embodiments, each of the pest control sensor  120  may include a separate transmitter and receiver for transmitting and receiving data from the server  104  using the network  106 . In still other embodiments, the gateway  122  may be configured to be hardwired to the network  106  via a cable. 
     The server  104  includes communications middleware, application software  140 , and a database  142 . It should be appreciated that the server  104  may be located on-site with the pest control device  120  or off site. The server  104  may be embodied as any type of computation or computer device capable of performing the functions described herein including, without limitation, a server, a computer, a multiprocessor system, a rack-mounted server, a blade server, a laptop computer, a notebook computer, a tablet computer, a wearable computing device, a network appliance, a web appliance, a distributed computing system, a processor-based system, and/or a consumer electronic device. It should be appreciated that the server  104  may be embodied as a single computing device or a collection of distributed computing devices. In the illustrative embodiment, the server  104  provides various virtual/logical components to allow sensor data of each of the pest control devices  120  received via the gateway  122  to be aggregated into database  142 . It should be appreciated that the server  104  may communicate with all remote pest control device groups  102 , evaluate resulting data, and take corresponding actions using an Application Service Provider (ASP) model. Among other things, the server  104  collects the sensor data from the pest control device group  102 , aggregates and processes sensor data, and determines what information needs to be forwarded to a customer or technician. In addition, the server  104  facilitates a data archive, notification and reporting process. 
     The client compute device  108  may be embodied as any type of computation or computer device capable of communicating with the server  104  including, without limitation, a computer, a multiprocessor system, a laptop computer, a notebook computer, a tablet computer, a wearable computing device, a network appliance, a web appliance, a distributed computing system, a processor-based system, and/or a consumer electronic device. In the illustrative embodiment, the client compute device  108  may selectively access the server  104  through the network  110 . The client compute device  108  may include browser subsystem, spreadsheet interface, email interface, Short Message Service (SMS) interface, and other interface sub systems. 
     The network  110  may be embodied as any type of network capable of facilitating communications between the client compute device  108  and the central pest data management server  104 . In the illustrative embodiment, the network  110  may be embodied as a wireless local area network (LAN) or a publicly-accessible, global network such as the Internet. However, it should be appreciated that, in some embodiments, the network  110  may be embodied as, or otherwise include, a cellular network or a wireless wide area network (WAN). As such, the network  110  may include any number of additional devices, such as additional computers, routers, and switches, to facilitate communications thereacross. 
     Referring now to  FIG. 2 , a pest control device  120  for detecting a presence of pests is shown in greater detail. The pest control device  120  includes a housing  202  defined by an exterior wall  204  and a top cover  206  enclosing an internal chamber  208 . In the illustrative embodiment, the internal chamber  208  houses a sensor  210 , a controller  212 , a power source  214 , and a wireless communication circuit  216 . In some embodiments, the internal chamber  208  may house a local indicator  218 . 
     The sensor  210  is configured to detect a targeted biochemical analyte found in the secretion of pests. For example, in the illustrative embodiment, the sensor  210  is configured to detect a targeted biochemical analyte found in the secretion of bed bugs. The sensor  210  is coupled to a conduit  222  on each side of the sensor  210 , which extends through the exterior wall  204  at an inlet  224  and an outlet  226 . The secretion of bed bugs enters the inlet  224  and flows into the sensor  210  through the conduit  222 . It should be appreciated that, in some embodiments, a fan  220  may be positioned in the internal chamber  208  near the outlet  226  in order to draw air from the inlet  224  towards the outlet  226  through the sensor  210 . 
     The sensor  210  may be embodied as any type of device, circuit, or component capable of performing the functions described herein. In the illustrative embodiment, the sensor  210  is embodied as a resonator sensor such as a quartz crystal microbalance (QCM). As shown in  FIG. 2 , the sensor  210  includes a sensor cell or quartz crystal resonator  230  such that the conduit  222  extends into the quartz crystal resonator  230  to distribute air through the quartz crystal resonator  230 . It should be appreciated that, in some embodiments, the sensor  210  may include a series of multiple sensor cells or quartz crystal resonators  230  that are arranged in parallel such that the conduit  222  is split into multiple lines into multiple quartz crystal resonators  230  to distribute air through each of the quartz crystal resonator  230 . 
     In use, the power source  214  provides power to the sensor  210  to oscillate the quartz crystal resonator  230 , and the quartz crystal resonator  230  is configured to measure a frequency of oscillation. The quartz crystal resonator  230  is further configured to generate sensor data that includes the frequency of the oscillating quartz crystal resonator  230 , which is indicative of mass change on the surface of the quartz crystal resonator  230 . It should be appreciated that the frequency of oscillation of quartz crystal resonator  230  is generally dependent on the sensor mass detected on the surface of the quartz crystal resonator  230 . For example, the frequency of oscillation decreases as the mass deposited on the surface of the quartz crystal resonator  230  increases. As such, a mass variation per unit area may be determined based on the sensor data received from the quartz crystal resonator  230 . Accordingly, the controller  212  of the pest control device  120  may further determine the change in sensor mass based on the change in frequency of oscillation. In some embodiments, the sensor  210  may be a small-scale QCM sensor, such as an openQCM. It should be appreciated that, in some embodiments, the sensor  210  may be any type of mass resonator that can detect the presence of the targeted biochemical analyte. In some embodiments, the sensor  210  may be embodied as a cantilever sensor. In other embodiments, the sensor  210  may be embodied as a cantilever sensor. 
     As shown in  FIG. 3 , the quartz crystal resonator  230  is coated with a sensor coating  306  on the surface of the quartz crystal resonator  230 . In the illustrative embodiment, the quartz crystal resonator  230  includes a quartz crystal  302  and an electrode  304 . It should be appreciated that the sensor coating  306  may be deposited on an entire surface or a partial surface of the quartz crystal  302 . 
     In the illustrative embodiment, the sensor coating  306  is made of an agent that reacts with the targeted biochemical analyte found in the secretion of bed bugs. In the illustrative embodiment, the targeted biochemical analyte is an unsaturated aldehyde compound, such as, for example, trans-2-hexenal (T2H), trans-2-octenal (T2O), 4-oxo-(E)-2-hexenal, and/or 4-oxo-(E)-2-octenal. In the illustrative embodiment, dioctyl-cyclic thiol intermediate (dioctyl-CTI) is used to form the sensor coating  306  because it selectively reacts with T2H, T2O, 4-oxo-(E)-2-hexenal, and/or 4-oxo-(E)-2-octenal. In the illustrative embodiment, the dioctyl-CTI has the formula 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  are each octyl. It should be appreciated that, in other embodiments, the agent may be cyclic thiol intermediate (CTI) or other CTI-functional group that reacts with the targeted biochemical analyte. When it reacts with T2H, T2O, 4-oxo-(E)-2-hexenal, and/or 4-oxo-(E)-2-octenal, dioctyl-CTI produces a product that has a higher molecular weight than the dioctyl-CTI alone. In the illustrative embodiment, the product has the formula 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  are each octyl and R 6  is pentyl. In some embodiments, dioctyl-CTI may be mixed with polymers to increase the viscosity of dioctyl-CTI to create a uniform film of the dioctyl-CTI on the quartz crystal resonator  230  and to prevent de-wetting of the dioctyl-CTI compounds on the quartz crystal resonator  230 . It should be appreciated that the frequency of oscillation of the quartz crystal resonator  230  is partially dependent on the mass of the agent coated on the quartz crystal resonator  230 . 
     In some embodiments, the agent of the sensor coating  306  is a cyclic thiol is of the formula I 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of hydrogen, C 3 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 3 , R 3′ , R 4 , and R 4′  are each independently selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, and C 6 -C 10  aryl; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     In some embodiments, X is S. In some embodiments, Z 1  is O. In some embodiments, Z 2  is O. In some embodiments, Z 1  and Z 2  are each O. In some embodiments, X is S, and Z 1  and Z 2  are each O. 
     In some embodiments, R 1  and R 2  are the same. In some embodiments, R 1  and R 2  are each independently C 4 -C 10  alkyl. In some embodiments, R 1  and R 2  are each C 4 -C 10  alkyl and are the same. In some embodiments, R 1  and R 2  are each independently C 6 -C 8  alkyl. In some embodiments, R 1  and R 2  are each C 6 -C 8  alkyl and are the same. In some embodiments, R 1  and R 2  are each octyl. 
     In some embodiments, at least one of R 1  and R 2  is coupled to the polymeric bulking group. In some embodiments, at least one of R 1  and R 2  is hydrogen. 
     In some embodiments, the polymeric bulking group is selected from the group consisting of a silicone, a polyolefin, a polyamide, a polyester, a polycarbonate, a polyaramide, a polyurethane, a polystyrene, an epoxy, a rubber, a starch, a protein, a cellulose, an acrylate, an ABS polymer, a PEEK polymer, a polyol, polyether, polyetherpolyol, and a copolymer of two or more of the foregoing. In some embodiments, the polymeric bulking group is a silicone. In some embodiments, the polymeric bulking group is a silsesquioxane. In some embodiments, the polymeric bulking group is crosslinked. 
     As used herein, “polymeric bulking group” refers to oligomers and polymers, which in some embodiments are silsesquioxanes. Examples of silsesquioxane compounds are described in Cordes, D., et al.,  Chem. Rev.  2010, 11, 2081-2173, expressly incorporated herein by reference. 
     In some embodiments, R 1  is —(OC 1 -C 4  alkyl) x R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x R 5 . In some embodiments, R 1  comprises —(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5 . In some embodiments, R 1  is of the formula —CH 2 O(CH 2 ) 3 S(CH 2 ) 3 R 5 . 
     In some embodiments, the cyclic thiol has a weight of about 200 Da to about 5000 Da. In some embodiments, the cyclic thiol has a weight of about 350 Da to about 5000 Da. In some embodiments, the cyclic thiol has a weight of about 1000 Da to about 5000 Da. 
     In some embodiments, a is 1. 
     In some embodiments, R 3 , R 3′ , R 4 , and R 4′  are each hydrogen. 
     In some embodiments, the cyclic thiol is of the formula 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  are each independently hexyl or octyl. 
     In some embodiments, the thiol group has a pKa of about 1 to about 4. In some embodiments, the thiol group has a pKa of about 2.5. 
     In some embodiments, the cyclic thiol is part of a composition that is free of metal thiol chelators. In some embodiments, the composition has a pH of about 2 to about 8. In some embodiments, the composition has a pH of about 2 to about 9. In some embodiments, the composition has a pH of about 7. 
     In some embodiments, when the agent of the sensor coating  306  reacts with the targeted biochemical analyte, a cyclic adduct is formed. In some embodiments, the cyclic adduct is of the formula II 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 3 , R 3′ , R 4 , and R 4′  are each independently selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, and C 6 -C 10  aryl; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     R 6  is C 1 -C 12  alkyl or oxo substituted C 1 -C 12  alkyl; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     In some embodiments, R 6  is propyl or pentyl. In some embodiments, R 6  is pentyl. 
     In some embodiments, R 6  is 1-oxopropyl or 1-oxopentyl. 
     In some embodiments, X is S. In some embodiments, Z 1  is O. In some embodiments, Z 2  is O. In some embodiments, Z 1  and Z 2  are each O. In some embodiments, X is S, and Z 1  and Z 2  are each O. 
     In some embodiments, R 1  and R 2  are the same. In some embodiments, R 1  and R 2  are each independently C 4 -C 10  alkyl. In some embodiments, R 1  and R 2  are each C 4 -C 10  alkyl and are the same. In some embodiments, R 1  and R 2  are each C 6 -C 8  alkyl and are the same. In some embodiments, R 1  and R 2  are each octyl. 
     In some embodiments, at least one of R 1  and R 2  is coupled to the polymeric bulking group. In some embodiments, at least one of R 1  and R 2  is hydrogen. 
     In some embodiments, the polymeric bulking group is selected from the group consisting of a silicone, a polyolefin, a polyamide, a polyester, a polycarbonate, a polyaramide, a polyurethane, a polystyrene, an epoxy, a rubber, a starch, a protein, a cellulose, an acrylate, an ABS polymer, a PEEK polymer, a polyol, polyether, polyetherpolyol, and a copolymer of two or more of the foregoing. In some embodiments, the polymeric bulking group is a silicone. In some embodiments, the polymeric bulking group is a silsesquioxane. In some embodiments, the polymeric bulking group is crosslinked. 
     In some embodiments, R 1  is —(OC 1 -C 4  alkyl) x R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x R 5 . In some embodiments, le comprises —(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5 . In some embodiments, le is of the formula —CH 2 O(CH 2 ) 3 S(CH 2 ) 3 R 5 . 
     In some embodiments, the cyclic adduct has a weight of about 200 Da to about 5000 Da. In some embodiments, the cyclic adduct has a weight of about 350 Da to about 5000 Da. In some embodiments, the cyclic adduct has a weight of about 1000 Da to about 5000 Da. 
     In some embodiments, a is 1. 
     In some embodiments, R 3 , R 3′ , R 4 , and R 4′  are each hydrogen. 
     In some embodiments, the cyclic adduct is of the formula 
     
       
         
         
             
             
         
       
     
     wherein R 1  and R 2  are each independently hexyl or octyl. In some embodiments, R 6  is propyl or pentyl. In some embodiments, R 6  is pentyl. In some embodiments, R 6  is 1-oxopropyl or 1-oxopentyl. 
     In some embodiments, the thiol group has a pKa of about 1 to about 4. In some embodiments, the thiol group has a pKa of about 2.5. 
     In some embodiments, the cyclic adduct is part of a composition that is free of metal thiol chelators. In some embodiments, the composition has a pH of about 2 to about 8. In some embodiments, the composition has a pH of about 2 to about 9. In some embodiments, the composition has a pH of about 7. 
     In some embodiments, the agent of the sensor coating  306  is a thiol is of the formula III 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene)x y R 5 ; 
     R 2  is selected from the group consisting of C 3 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     In some embodiments, X is S. In some embodiments, Z 1  is O. In some embodiments, Z 2  is O. In some embodiments, Z 1  and Z 2  are each O. In some embodiments, X is S, and Z 1  and Z 2  are each O. 
     In some embodiments, R 1  and R 2  are the same. In some embodiments, R 1  and R 2  are each independently C 4 -C 10  alkyl. In some embodiments, R 1  and R 2  are each C 4 -C 10  alkyl and are the same. In some embodiments, R 1  and R 2  are each independently C 6 -C 8  alkyl In some embodiments, R 1  and R 2  are each C 6 -C 8  alkyl and are the same. In some embodiments, R 1  and R 2  are each octyl. 
     In some embodiments, at least one of R 1  and R 2  is coupled to the polymeric bulking group. In some embodiments, at least one of R 1  and R 2  is hydrogen. 
     In some embodiments, the polymeric bulking group is selected from the group consisting of a silicone, a polyolefin, a polyamide, a polyester, a polycarbonate, a polyaramide, a polyurethane, a polystyrene, an epoxy, a rubber, a starch, a protein, a cellulose, an acrylate, an ABS polymer, a PEEK polymer, a polyol, polyether, polyetherpolyol, and a copolymer of two or more of the foregoing. In some embodiments, the polymeric bulking group is a silicone. In some embodiments, the polymeric bulking group is a silsesquioxane. In some embodiments, the polymeric bulking group is crosslinked. 
     In some embodiments, R 1  is —(OC 1 -C 4  alkyl) x R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x R 5 . In some embodiments, le comprises —(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5 . In some embodiments, le is of the formula —CH 2 O(CH 2 ) 3 S(CH 2 ) 3 R 5 . 
     In some embodiments, the thiol has a weight of about 200 Da to about 5000 Da. In some embodiments, the thiol has a weight of about 350 Da to about 5000 Da. In some embodiments, the thiol has a weight of about 1000 Da to about 5000 Da. 
     In some embodiments, a is 1. 
     In some embodiments, the thiol group has a pKa of about 1 to about 4. In some embodiments, the thiol group has a pKa of about 2.5. 
     In some embodiments, the thiol is part of a composition that is free of metal thiol chelators. In some embodiments, the composition has a pH of about 2 to about 8. In some embodiments, the composition has a pH of about 2 to about 9. In some embodiments, the composition has a pH of about 7. 
     In some embodiments, when the agent of the sensor coating  306  reacts with the targeted biochemical analyte, an adduct is formed. In some embodiments, the adduct is of the formula II 
     
       
         
         
             
             
         
       
     
     or a tautomer thereof, wherein 
     X is S or O; 
     Z 1  and Z 2  are each independently O or S; 
     R 1  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 2  is selected from the group consisting of hydrogen, C 1 -C 12  alkyl, C 2 -C 12  alkenyl, C 6 -C 10  aryl, 5- to 7-membered heteroaryl, —OR 5 , —SR 5 , —(OC 1 -C 4  alkylene) x R 5 , —(SC 1 -C 4  alkylene) y R 5 , —(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , —(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x R 5 , C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y R 5 , C 1 -C 3  alkylene(OC 1 -C 4  alkylene) x (SC 1 -C 4  alkylene) y R 5 , and C 1 -C 3  alkylene(SC 1 -C 4  alkylene) y (OC 1 -C 4  alkylene) x R 5 ; 
     R 5  is selected from the group consisting of hydrogen, C 1 -C 8  alkyl, C 2 -C 8  alkenyl, C 6 -C 10  aryl, and a polymeric bulking group; 
     R 6  is C 1 -C 12  alkyl or oxo substituted C 1 -C 12  alkyl; 
     a is 0 or 1; and 
     x and y are each independently an integer from 1 to 10. 
     In some embodiments, R 6  is propyl or pentyl. In some embodiments, R 6  is pentyl. In some embodiments, R 6  is 1-oxopropyl or 1-oxopentyl. 
     In some embodiments, X is S. In some embodiments, Z 1  is O. In some embodiments, Z 2  is O. In some embodiments, Z 1  and Z 2  are each O. In some embodiments, X is S, and Z 1  and Z 2  are each O. 
     In some embodiments, R 1  and R 2  are the same. In some embodiments, R 1  and R 2  are each independently C 4 -C 10  alkyl. In some embodiments, R 1  and R 2  are each C 4 -C 10  alkyl and are the same. In some embodiments, R 1  and R 2  are each independently C 6 -C 8  alkyl. In some embodiments, R 1  and R 2  are each C 6 -C 8  alkyl and are the same. In some embodiments, R 1  and R 2  are each octyl. 
     In some embodiments, at least one of R 1  and R 2  is coupled to the polymeric bulking group. In some embodiments, at least one of R 1  and R 2  is hydrogen. 
     In some embodiments, the polymeric bulking group is selected from the group consisting of a silicone, a polyolefin, a polyamide, a polyester, a polycarbonate, a polyaramide, a polyurethane, a polystyrene, an epoxy, a rubber, a starch, a protein, a cellulose, an acrylate, an ABS polymer, a PEEK polymer, a polyol, polyether, polyetherpolyol, and a copolymer of two or more of the foregoing. In some embodiments, the polymeric bulking group is a silicone. In some embodiments, the polymeric bulking group is a silsesquioxane. In some embodiments, the polymeric bulking group is crosslinked. 
     In some embodiments, R 1  is —(OC 1 -C 4  alkyl) x R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x R 5 . In some embodiments, R 1  comprises —(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5  or C 1 -C 3  alkyl(OC 1 -C 4  alkyl) x (SC 1 -C 4  alkyl) y R 5 . In some embodiments, R 1  is of the formula —CH 2 O(CH 2 ) 3 S(CH 2 ) 3 R 5 . 
     In some embodiments, the adduct has a weight of about 200 Da to about 5000 Da. In some embodiments, the adduct has a weight of about 350 Da to about 5000 Da. In some embodiments, the adduct has a weight of about 1000 Da to about 5000 Da. 
     In some embodiments, a is 1. 
     As described above, the agent of the sensor coating  306  is configured to react with the targeted biochemical analyte to produce a product that has a higher molecular weight. In use, the initial increase in sensor mass detected on the surface of the quartz crystal resonator  230  is determined based on the sensor data. As discussed above, in the illustrative embodiment, the sensor data includes the frequency of the oscillating quartz crystal resonator  230 , and the change in frequency is generally proportional to the change in sensor mass. Accordingly, the initial increase in sensor mass is determined by measuring the change in frequency of the oscillating quartz crystal resonator  230  as discussed in detail below. 
     In some embodiments, the initial increase in sensor mass may also be determined based on an absolute mass change. To do so, a current surface mass and an initial surface mass on the quartz crystal resonator  230  prior to the reaction may be compared to measure the initial increase in sensor mass. It should be appreciated that the detection of a subsequent increase in sensor mass is determined by comparing the current surface mass and a subsequent surface mass on the quartz crystal resonator  230 . 
     The mass change generally correlates to the concentration of targeted biochemical analyte detected on the quartz crystal resonator  230 . However, it should be appreciated that the amount of the agent available to react with the targeted biochemical analyte may influence the reaction rate, thereby affecting the mass change and/or the mass change rate detected on the surface of the quartz crystal resonator  230 . Such mass increase associated with the reaction is detected by the controller  212  of the pest control device  102 , which is discussed in detail in  FIGS. 6 and 8 . 
     In some embodiments, the mass change rate may be influenced by a detection response time of the sensor  210 . The detection response time may increase if an accumulation of the targeted biochemical analyte in air surrounding the sensor  210  is required in order to generate a signal or sensor data that amounts to a measureable change indicative of a presence of bed bugs. In other words, at low concentration of the targeted biochemical analyte, the mass change of the quartz crystal resonator  230  resulted from the reaction may not be sufficient until the targeted biochemical analyte is accumulated to a predetermined amount. In some embodiments, a pre-concentrator may be used to reach a minimum predetermined amount of the targeted biochemical analyte such that the sensor  210  can immediately detect a low concentration of the targeted biochemical analyte. 
     It should be noted that the amount of the agent of the sensor coating  306  decreases as the agent reacts with the targeted biochemical analyte. It should be appreciated that, in some embodiments, the reaction is reversible from the product to the agent based on heat. In such embodiments, the pest control device  120  further includes a heating element (not shown). When the amount of the agent of the sensor coating  306  reaches a threshold level, the pest control device  120  applies heat to the quartz crystal resonator  230  to reverse the reaction and recover the agent of the sensor coating  306 . In some embodiments, the pest control device  120  may generate a local or remote alert indicating that the sensor  210  requires maintenance to replenish the agent of the sensor coating  306  or replace the quartz crystal resonator  230  or the sensor  210 . 
     Referring back to  FIG. 2 , the controller  212  may be embodied as any type of controller, circuit, or component capable of performing the functions described herein. The controller  212  is configured to determine the presence of bed bugs by analyzing sensor data produced by the sensor  210 . Specifically, in the illustrative embodiment, the quartz crystal resonator  230  of the sensor  210  generates sensor data. The sensor data includes, among other things, mass changes on the surface of the quartz crystal resonator  230 . It should be appreciate that the mass change on the quartz crystal resonator  230  indicates that the agent of the sensor coating  306  of the quartz crystal resonator  230  is being converted to a product that has a different molecular weight, and the mass change rate is generally proportional to the rate of reactions to convert the agent into the product. 
     As discussed above, in the illustrative embodiment, the product resulting from the reaction between the agent (e.g., dioctyl-CTI) and the targeted biochemical analyte, such as T2H, T2O, 4-oxo-(E)-2-hexenal, and/or 4-oxo-(E)-2-octenal, has a higher molecular weight compared to the molecular weight of the dioctyl-CTI. Accordingly, the controller  212  determines whether the mass increase exceeds a predefined threshold rate. The predefined threshold rate is a base mass change rate in the presence of bed bugs. For example, in some embodiments, the base mass change may be a minimum mass change rate in the presence of bed bugs. In other embodiments, the base mass change may be a minimum mass change rate plus some additional safety factor to avoid false positives or unwanted detections. For example, in some cases, environmental factors, such as temperature and humidity in air surrounding the sensor  210 , may affect the accuracy of the mass change rate detected and result in sensor drift. The inclusion of some additional safety factors may compensate for unpredicted environmental effects to decrease unwanted detections due to sensor drift. 
     As discussed above, the initial increase in sensor mass detected on the surface of the quartz crystal resonator  230  is determined by measuring the change in frequency of the oscillating quartz crystal resonator  230 . In some embodiments, as discussed above, the initial increase in sensor mass may also be determined based on an absolute mass change by comparing a current mass on the quartz crystal resonator  230  and an initial mass on the quartz crystal resonator  230  prior to the reaction. It should be appreciated that the detection of a subsequent mass increase is determined by comparing the current mass of the quartz crystal resonator  230  and a subsequent mass of the quartz crystal resonator  230 . It should be appreciated that, in some embodiments, the sensor data may be processed at the server  104 . 
     In some embodiments, the sensor  210  may detect the presence of bed bugs by detecting the decrease in sensor mass upon heating the quartz crystal resonator  230 . To do so, the sensor  210  may determine the mass detected on the surface of the quartz crystal resonator  230  before and after applying the heat to the quartz crystal resonator  230  and determine whether a change in mass exceeds a predefined threshold. As discussed above, when the heat is applied to the quartz crystal resonator  230 , the product resulted from the reaction between the agent and the targeted biochemical analyte releases the targeted biochemical analyte and results in decrease in sensor mass to detect the presence of bed bugs 
     In some embodiments, the sensor  210  may determine both the mass gain and mass loss to eliminate false positives or unwanted detections. For example, in some cases, environmental factors, such as dust or other particles in air surrounding the sensor  210  may interact with the agent of the sensor coating  306  and increase the sensor mass detected on the surface of the quartz crystal resonator  230 . In such embodiments, the sensor  210  may identify false positives or unwanted detections if the increase in the sensor mass prior to the heating exceeds a first predefined threshold while the decrease in the sensor mass after the heating does not exceed a second predefined threshold. 
     The power source  214  may be embodied as any type of device, circuit, or component capable of providing electrical power to the components of the pest control device  120 , such as the controller  212 , the sensor  210 , the wireless communication circuit  216 , the local indicator  218 , or the fan  220  as needed. In some embodiments, the power source  214  may be electrochemical cells or a battery. 
     The wireless communication circuit  216  may be embodied as any type of device, circuit, or component capable of enabling communications between the pest control device  104  and the gateway  122 . Each pest control device  120  is configured to periodically or continually communicate with the gateway  122  to transmit the sensor data to the server  104  using the network  106 . For example, the sensor data may include, among other things, notifications such as a detection of bed bug and/or an indication that the sensor requires a maintenance. To do so, the wireless communication circuit  216  may be configured to use any one or more communication technologies (e.g., wireless or wired communications) and associated protocols (e.g., Ethernet, Bluetooth®, WiMAX, LTE, 5G, etc.) to effect such communication. 
     The local indicator  218  may be embodied as any type of indicator that is capable of generating an alert to notify a human operator or a technician. For example, the local indicator  218  may be embodied as a visual and/or audible indicator. In some embodiments, the visual indicator  218  may include a light emitting diode (LED), fluorescent, incandescent, and/or neon type light source. The audible indicator may generate an alert sound to notify the technician. In the illustrative embodiment, the local indicator  218  generates an alert indicative of a presence or absence of bed bugs. For example, in some embodiments, the LED light indicator  218  may be energized to project a colored light, change color, or change from a non-blinking light to a blinking light to indicate the presence of bed bugs. In other embodiments, the audible local indicator  218  may generate sound to indicate the presence of bed bugs. 
     In some embodiments, the local indicator  218  may also output a signal indicative of whether the sensor  230  requires maintenance. For example, the local alert may indicate a malfunction of the sensor  230 . In some embodiments, the local alert may indicate the depletion of the agent of the sensor  210 . In such embodiments, the LED light indicator  218  may be energized to project a colored light, change color, or change from a non-blinking light to a blinking light to indicate the presence of bed bugs. It should be appreciated that the color of the LED light indicator  218  indicating the sensor maintenance may be different from the color of the LED light indicator  218  indicating the bed bug detection. In some embodiments, the visual indicator may be used to indicate the presence of bed bugs and an audible indicator may be used to indicate that the sensor  210  requires maintenance or vice versa. 
     It should be appreciated that, in some embodiments, the pest control device  120  may further include a handle (not shown) on a housing member  202  to provide a grip to a human operator or a technician. The technician may grip the handle of the pest control device  120  and manually move the pest control device  120  to identify a localized area of the targeted biochemical analyte indicative of a presence of bed bugs. 
     Referring now to  FIG. 4 , the gateway  122  includes a controller  402  with a memory  404 , a wireless network interface  406  with an antenna  408 , and a modem  412  with an antenna  414 . The controller  402  may be embodied as any type of controller, circuit, or component capable of performing the functions described herein including, without limitation, a computer, a multiprocessor system, a laptop computer, a notebook computer, a tablet computer, a wearable computing device, a network appliance, a web appliance, a distributed computing system, a processor-based system, and/or a consumer electronic device. In some embodiments, the controller  402  may be of a microcontroller type, such as model no. C805F120 provided by Cygnal Technologies. 
     The memory  404  may be embodied as any type of volatile or non-volatile memory or data storage capable of performing the functions described herein. In operation, the memory  404  may store various data and software used during operation of the gateway  122  such as programs, libraries, and drivers. In some embodiments, the memory  404  may temporarily store and aggregate sensor data received from the pest control devices  120  prior to transmitting the sensor data to the server  104  over the network  106 . 
     In the illustrative embodiment, the modem  412  with the antenna  414  is configured to interface with a cellular network or a wireless WAN network  106  to communicate with network  106 . In some embodiments, the modem  408  may utilize General Packet Radio Service (GPRS) through a Global System for Mobile communications (GSM) protocol. In some embodiments, the model  408  may be of a hardwired dial-up and/or coaxial cable type. 
     In the illustrative embodiment, the wireless network interface  406  with the antenna  408  is configured to interface with a wireless communication network as defined by a corresponding pest control group  102  to communicate with the pest control devices  120 . In some embodiments, the wireless communication network may be a local area network (LAN) type. 
     Referring now to  FIG. 5 , in use, the pest control system  100  may execute a routine  500  for detecting a presence of bed bugs. The routine  500  begins with block  502  in which the communication components of pest control system  100  are initialized to form new communication paths from each of the pest control device  120  to the server  104  or the client compute device  108 . For example, the wireless network interface  406  and the modem  412  of the gateway  122  may be initialized to establish links to networks. 
     In block  504 , each of the pest control device  120  obtains and analyzes data generated by the sensor  210  of the pest control device  120 . As described above, in the illustrative embodiment, the sensor  210  includes a quartz crystal resonator  230  that is configured to output sensor data, and a surface of the quartz crystal resonator  230  has the sensor coating  306 , which includes the agent. As discussed above, the agent of the sensor coating  306  selectively reacts with the targeted biochemical analyte secreted by pests. During the reaction, the agent is converted to a product with a different molecular weight compared to the molecular weight of the agent. As discussed above, the quartz crystal resonator  230  outputs sensor data that includes a frequency of oscillation, which is indicative of the mass changes on the surface of the quartz crystal resonator  230 . As discussed above, the change in frequency is generally proportional to the change in sensor mass deposited on the surface of the quartz crystal resonator  230 . Accordingly, the controller  212  of the pest control device  120  analyzes the sensor data of the quartz crystal resonator  230  and determines a presence of pests based on a level of mass change, which is discussed in detail in  FIGS. 6 and 7 . 
     In some embodiments, the sensor data may include a status of the sensor  210 . For example, the status of the sensor  210  may include an amount of remaining agent of the sensor coating  306 . As discussed above, the frequency of oscillation of the quartz crystal resonator  230  partially depends on the mass of the agent coated on the quartz crystal resonator  230 . As such, the remaining agent coated on the quartz crystal resonator  230  may be estimated based on the frequency of oscillation of the quartz crystal resonator  230 . In other embodiments, each of the pest control device  120  may determine an amount of the agent that has been converted to the product, thereby determine the amount of the agent remaining in the sensor coating  306 . It should be appreciated that having a sufficient amount of the agent of the sensor coating  306  is necessary for accurate detection of the presence of pests. 
     In block  506 , the sensor data of the pest control device  120  is transmitted to the pest data management server  104 . To do so, the pest control device  120  transmits the sensor data to the gateway  122 . The gateway  122  subsequently transmits the sensor data to the server  104  via the network  106 . 
     In block  508 , the server  104  outputs the sensor data. In some embodiments, the server  104  may perform corresponding actions using the application  140 . For example, the application  140  includes a notifications and alarm service that can dispatch alerts to the client compute device  108  based on conditions set within the database  142 . 
     Referring now to  FIGS. 6 and 7 , in use, the controller  212  of the pest control device  120  may execute a routine  600  for detecting a presence of bed bugs by determining rate of changes in sensor mass and a routine  700  for determining whether to issue an alert notification. The routine  600  begins with block  602  in which the controller  212  determines whether the sensor  210  of the pest control device  120  is active. If the controller  212  determines that the sensor  210  is not active, the routine  600  loops back to block  602  to continue monitoring for an active sensor  210 . If, however, the controller  212  determines that the sensor  210  is active, the routine  600  advances to block  604 . 
     In block  604 , the controller  212  receives sensor data from the sensor  210 . In the illustrative embodiment, the sensor or quartz crystal microbalance  210  generates sensor data indicative of mass changes on the surface of the quartz crystal resonator  230  of the quartz crystal microbalance  210 . As described above, the sensor data includes the frequency of oscillation of quartz crystal resonator  230 , which is generally proportional to the change in sensor mass. Based on the received sensor data, in block  606 , the controller  212  determines a rate of change in sensor mass (i.e., the mass change rate on the surface of the quartz crystal resonator  230 ). 
     In block  608 , the controller  212  determines whether the determined rate of change in the sensor mass exceeds a predefined threshold rate. It should be appreciated that the predefined threshold rate is the base mass change rate in the presence of bed bugs and is used to reduce false positive detection of bed bugs. As discussed above, the base mass change rate is a minimum mass change rate in the presence of bed bugs. In some embodiments, the base mass change may be a minimum mass change rate plus some additional safety factor to avoid false positives or unwanted detections. 
     If the controller  212  determines that the rate of change does not exceeds the predefined threshold rate, the controller  212  determines that no bed bug is detected, and the routine  600  skips ahead skips to block  710  of the routine  700  shown in  FIG. 7 , which is described in detail below. If, however, the controller  212  determines that the rate of change exceeds the predefined threshold rate, the routine  600  advances to block  610 . In block  610 , the controller  212  activates or starts a timer when the rate of change in sensor mass exceeds the predefined threshold rate. It should be appreciated that, in some embodiments, the controller  212  may record a start time at which the rate of change in sensor mass exceeded the predefined threshold rate. In other words, the start time is the time at which the pest control device  108  detected a presence of bed bugs. 
     To further reduce false positive detection of bed bugs, the controller  212  determines how long the mass change rate has exceeded the predefined threshold rate. To do so, the controller  212  receives subsequent sensor data from the sensor  210  in block  612 . Based on the subsequent sensor data, the controller  212  determines a rate of change in sensor mass in block  614 . 
     In block  616 , the controller  212  determines whether the rate of change based on the subsequent sensor data still exceeds the predefined threshold rate. If the controller  212  determines that the rate of change exceeds the predefined threshold rate, the routine  600  loops back to block  612  to continue to receive subsequent sensor data. If, however, the controller  212  determines that the rate of change does not exceed the predefined threshold rate, the routine  600  advances to block  618 . 
     In block  618 , the controller  212  stops the timer. It should be appreciated that, in some embodiments, the controller  212  records an end time at which the rate of change exceeded the predefined threshold rate. In other words, the end time is the time at which the pest control device  108  no longer detects a presence of bed bugs. The routine  600  subsequently proceeds to block  702  of the routine  700  shown in  FIG. 7  to determine whether to issue an alert notification. 
     In block  702  shown in  FIG. 7 , the controller  212  determines a time interval measured by the timer. It should be appreciated that the determined time interval indicates the time period that the bed bugs have been detected. 
     In block  704 , the controller  212  determines whether the time interval is greater than a predefined time period. As discussed above, the predefined time period is used to reduce false positive detection. If the time interval is less than the predefined time period, the controller  212  determines that such detection is likely be a false positive, and the routine  700  skips ahead to block  708  in which the controller  212  records the time interval. The false positive may be due to, for example, unexpected environmental factors, unexpected malfunctioning of the device, and/or human error. 
     If, however, the controller  212  determines that the time interval is greater than the predefined time period, the routine  700  advances to block  706 . In block  706 , the controller  212  issues a bed bug detection alert notification. In some embodiments, the controller  212  may issue the local bed bug detection alert notification via the local indicator  218 . In other embodiments, the controller  212  may issue the bed bug detection alert notification to the server  104 . In block  708 , the controller  212  records the time interval. 
     Subsequent to detecting the presence of bed bugs, the controller  212  further determine an agent level of the sensor coating  306  on the quartz crystal resonator  230  of the sensor  210  to determine when to replenish the sensor coating  306  on the quartz crystal resonator  230  or replace the quartz crystal resonator  230  and/or the sensor  210 . It should be appreciated that, in some embodiments, the controller  212  may simultaneously determine the agent level and a presence of bed bug. 
     In block  710 , the controller  212  determines a level of the agent of the sensor coating  306  on the quartz crystal resonator  230 . To do so, in some embodiments, in block  712 , the controller  212  may determine the agent level based on the sensor data. As discussed above, the frequency of oscillation of the quartz crystal resonator  230  is partially dependent on the mass of the agent coated on the quartz crystal resonator  230 . As such, the controller  212  may estimate the amount of remaining agent based on the frequency of oscillation of the corresponding quartz crystal resonator  230 . 
     In some embodiments, in block  714 , the controller  212  may determine the agent level by analyzing the rate of changes in sensor mass. For example, the controller  212  determines the rate of changes in the sensor mass over a predetermined period of time and calculate a total mass change over the predetermined period of time. It should be appreciated that the total mass change is a weight difference between a weight of the product produced over the predetermined period of time and a weight of agent that reacted with the targeted biochemical analyte to produce the product. The controller  212  may calculate the amount of the agent that has been consumed in the reaction from the total mass change. Accordingly, the controller  212  may determine the amount of agent remaining on the quartz crystal resonator  230  available to react with the targeted biochemical analyte. 
     In some embodiments, in block  716 , the controller  212  may determine the agent level of the sensor  210  by comparing the current sensor mass to a theoretical sensor mass. The theoretical sensor mass is a sensor mass that is expected if all amount of the agent of the sensor coating  306  is converted to the product. 
     In block  718 , the controller  212  determines whether the agent level is below a threshold level. The threshold level is set based on a minimum amount of agent in the sensor coating  306  required to react with the targeted biochemical analyte. In other words, if the agent level is below the threshold level, the agent is depleted, and no further reaction can occur. 
     If so, the routine  700  advances to block  720  in which the controller  212  issues a notification to replace the sensor  210 . In some embodiments, the controller  212  may issue the local replacement notification via the local indicator  218 . In other embodiments, the controller  212  may issue the notification to the server  104 . 
     If, however, the controller  212  determines that the agent level is higher than the threshold level, the routine  700  skips block  720 . The routine  700  may loop back to block  604  of the routine  600  in  FIG. 6  to continue receiving sensor data to determine the presence of bed bugs and the agent level of the sensor  210 . 
     Referring now to  FIGS. 8A and 8B , in use, the controller  212  of the pest control device  120  may execute an alternative routine  800  alternative to the routine  600  for detecting a presence of bed bugs by comparing the rate of change in frequency over time. The routine  800  begins with block  802  in which the controller  212  determines whether the sensor  210  of the pest control device  120  is active. If the controller  212  determines that the sensor  210  is not active, the routine  800  loops back to block  802  to continue monitoring for an active sensor  210 . If, however, the controller  212  determines that the sensor  210  is active, the routine  800  advances to block  804 . 
     In block  804 , the controller  212  receives first sensor data and subsequently receives second sensor data after a predefined time. As discussed above, in the illustrative embodiment, the sensor data includes the frequency of the oscillating quartz crystal resonator  230 . Accordingly, in block  806 , the controller  212  determines a first slope of frequency change (i.e., a rate of change in frequency) during the predefined time based on the first and second sensor data. However, it should be appreciated that in other embodiments, the controller  212  determines a first slope of any signal change based on the first and second sensor data. 
     Subsequently, in block  808 , the controller  212  further receives subsequent sensor data after the predefined time. The controller  212  then determines a second slope of frequency change based on the second and subsequent sensor data in block  810 . 
     In block  812 , the controller  212  determines whether the second slope is different from the first slope. In other words, the controller  212  compares the first and second rate of changes in frequency. As discussed above, the change in frequency is indicative of the change in sensor mass. It should be noted, however, that the sensitivity and/or accuracy of the sensor detection may decrease due to sensor drift over time and may prevent the controller  212  from detecting the presence of low-level targeted biochemical analyte. As such, by calculating the difference in the rates of frequency change to determine the presence of bed bugs, the controller  212  may minimize the influence of possible sensor drift when monitoring for long periods of time. 
     If the controller  212  determines that the second slope is not different from the first slope (i.e., the rate of change in frequency has not changed), the controller  212  determines that no bed bug is detected, and the routine  800  skips to block  710  of the routine  700  shown in  FIG. 7 . 
     If, however, the controller  212  determines that the second slope is different from the first slope, the routine  800  advances to block  814  shown in  FIG. 8B  which the controller  212  activates a timer to indicate a start time at which the controller  212  detected an abrupt change in frequency. In other words, the start time is the time at which the pest control device  108  detected a presence of bed bugs. 
     To further reduce false positive detection of bed bugs, the controller  212  determines how long the rate of change in frequency (i.e., the rate of change in sensor mass) is changing. To do so, the controller  212  receives subsequent sensor data from the sensor  210  in block  612 . Based on the subsequent sensor data, the controller  212  determines a subsequent slope of frequency change in block  818 . 
     In block  820 , the controller  212  determines whether the subsequent slope is different from a previous slope. It should be appreciated that the previous slope is a slope that was determined immediately prior to the subsequent slope. If the controller  212  determines that the slope has changed, the routine  800  loops back to block  816  to continue to receive subsequent sensor data. If, however, the controller  212  determines that the slope has not changed, the routine  800  advances to block  822 . 
     In block  822 , the controller  212  stops the timer to indicate an end time at which the controller  212  detected no change in frequency. In other words, the end time is the time at which the pest control device  108  no longer detects a presence of bed bugs. The routine  800  then advances to block  702  of the routine  700  shown in  FIG. 7  to determine whether to issue a bed bug detection alert notification based on the time interval between the start time and end time, which is discussed in detail above. 
     It should be appreciated that the sensor  210  may be embodied as other types of sensors that are capable of detecting the targeted biochemical analyte. For example, as discussed above, the sensor  210  may be embodied as a cantilever sensor. In such embodiments, the cantilever sensor includes a body and one or more cantilevers that project outwardly from the body. Each cantilever is coated with the agent, which reacts with the targeted biochemical analyte, and is configured to oscillate in a vertical direction. To initiate the oscillation of each cantilever, the cantilever sensor may be excited by resistive heating to cause a layer thermal expansion mismatch. When the agent of the oscillating cantilever reacts with the targeted biochemical analyte, the resonant frequency of the oscillating cantilever changes due to increase in mass on the cantilever. As discussed above, the frequency change may be used to detect the presence of bed bugs. In some embodiments, the cantilever sensor may further include a piezoresistive pressure sensor. In such embodiments, the piezoresistive pressure sensor measures a degree of deformation (e.g., bending) of the cantilever during the oscillation and determines the presence of bed bugs if the degree of deformation is greater than a predefined threshold. 
     Referring now to  FIGS. 9-12 , another embodiment of a pest control device (hereinafter pest control device  890 ) is shown. In the illustrative embodiment, the pest control device  890  includes a sensor  908  that is positioned in a harborage device  900 . It should be appreciated that the sensor  908  may take the form of the sensor  210  described above in reference to  FIGS. 1-8  or any of the other sensors described above. The harborage device  900  is configured to create favorable conditions to attract pests (e.g., color, temperature, texture, and/or odor that appeals to targeted pests) to cause them to enter and congregate in the harborage device. For example, in the illustrative embodiment, the harborage device  900  includes a light blocking material to attract pests such as, for example, bed bugs, that prefer a dark and shady environment. Additionally, in the illustrative embodiment, the harborage device  900  includes an attractive color that appeals to the targeted pests. 
     As shown in  FIG. 9 , the harborage device  900  is configured to be secured to a bed headboard  952  of a bed  950 . For example, the harborage device  900  may be secured to a surface of the bed headboard  952  that faces away from the bed mattress  954  and toward the wall of the room. Such a harborage device  900  is configured to attract pests that have a preferred habitat near beds or mattresses, for example, bed bugs. It should be appreciated that, in some embodiments, the harborage device  900  may be secured to any surface of the bed  950  using a fastener or adhesive that do not produce volatile compounds that may react with the targeted analyte or otherwise interfere with the sensor. In other embodiments, the harborage device  900  may be placed near the bed  950  or any other environment that is prone to pest infestation. 
     The harborage device  900  includes an inner chamber  940  and a plurality of inlets  928  that open into the chamber  940  to permit entry of the pests. It should be appreciated that each inlet  928  is sized to allow easy access for pests and provide oxygen within the harborage device  900  for harboring the pests. To do so, the width of each inlet  928  may be determined based on the size of the targeted pests to ensure that each inlet  928  is sized to allow entrance of the targeted pests while reducing unnecessary diffusional losses of the targeted analyte to the environment of the harborage device  900 . For example, if the harborage device  900  is configured to detect the presence of bed bugs, the optimal width of each inlet  928  may range from 3 mm to 100 mm. 
     In the illustrative embodiment, the harborage device  900  is configured to be opened by a technician or other user to permit access to the chamber  940 . Referring now to  FIGS. 10 and 11 , the harborage device  900  is shown in its open configuration. The harborage device  900  includes a bottom panel  902  and a top panel  904  that is pivotably coupled to the bottom panel  902  via a hinge  906 . The hinge  906  allows the top panel  904  to move relative to the bottom panel  902  to permit access to the inner chamber  940 . In use, the harborage device  900  is folded via the hinge  906  such that the top panel  904  is positioned on top of the bottom panel  902  to close the harborage device  900  (see  FIGS. 9 and 12-13 ). It should be appreciated that, in some embodiments, the bottom panel  902  may be coupled to the top panel  904  via other types of fastener that permit the panels to be moved apart and permit access to the inner chamber  940 . 
     As shown in  FIG. 10 , the bottom panel  902  includes an outer frame  912  and a plurality of openings  914  disposed in the outer frame  912 . The top panel  904  also includes an outer frame  922  that cooperates with the outer frame  912  of the bottom panel  902  to define the inner chamber  940 . The top panel  904  also includes a plurality of openings  924  disposed in its outer frame  922  that are configured to align with the corresponding openings  914  of the bottom panel  902  to define the inlets  928  of the harborage device  900  when the harborage device  900  is closed (i.e., when the top panel  904  is folded on the bottom panel  902  via the hinge  906  as shown in  FIGS. 11 and 12 .) 
     The panels  902 ,  904  further include inner surfaces  918 ,  926 , respectively. In the illustrative embodiment, the inner surfaces  918 ,  926  are coated with a textured material to attract pests into the harborage device  900 . For example, the textured material may be a fibrous material. The textured material is configured to provide traction for pests to move inside of the harborage device  900  along the inner surfaces  918 ,  926 . For example, the textured material may be woven (e.g. fabric) or non-woven (e.g. paper) and may be made of synthetic, natural, or blended fibers. In some embodiments, the textured material may be colored to attract pests. For example, to attract bed bugs, a paper with red-shade or black color may be used. It should be appreciated that the textured material is configured to provide minimal to no sorption of the targeted analyte to prevent or minimize any interference with the sensor detection. In some embodiments, a thickness of the texture material may be optimized to reduce the sorption of the targeted analyte. 
     Additionally, the bottom panel  902  further includes a plurality of inner walls  916  extending from the inner surface  918 . As described in detail below, the plurality of inner walls  916  divide the inner chamber  940  into a plurality of channels  932 . Each channel  932  is sized to receive one or more pests and configured to direct airflow from the inlets  928  toward the sensor  908  as indicated by arrows  934 . It should be appreciated that, in some embodiments, the flow channels  932  may taper toward peripheries of the harborage device  900 . Such tapered flow channels  932  are adapted to increase concentration of the targeted analyte in the harborage device  900  by restricting diffusion of the targeted analyte to narrower flow channels  932  and reduce losses of the targeted analyte to air space surrounding the pests. 
     The plurality of inner walls  916  include a plurality of guide walls  936  and a plurality of barrier walls  938 . Each guide wall  936  is positioned on each side of an inlet  928  and extends in a first direction as shown by arrow  968 . Each pair of guide walls  936  defines an inlet channel  960  of the plurality of channels  932 . Each barrier wall  938  is spaced apart from the ends of the guide walls  936  and includes a first wall section  942 , a second wall section  944  extending from an end of the first wall section  942 , and a third wall section  946  extending from an opposite end of the first wall section  942  to form a generally U-shaped barrier. 
     The first wall section  942  is configured to extend in the second direction orthogonal to the first direction, while the second wall section  944  and the third wall section  946  extend parallel to the guide walls  936 . It should be appreciated that the second wall section  944  cooperates with the guide wall  936  to define a first side channel  962  of the plurality of channels  932 , while the third wall section  946  cooperates with the guide wall  936  to define a second side channel  964  of the plurality of channels  932 . As described above, the plurality of channels  932  cooperate to define a flow path in the inner chamber  940  from the inlets  928  toward the sensor  908  as indicated by the arrows  934 . To do so, the first channel  960  is configured to direct the airflow in the first direction from the corresponding inlet  928  and the first and second side channels  962 ,  964  are configured to direct the airflow in a third direction opposite the first direction as shown in arrow  970 . Additionally, a fourth channel  966  is defined between the barrier walls  938 , specifically between a third wall section  946  of one barrier wall  938  and a second wall section  944  of another barrier wall  938 , to direct airflow in the first direction as shown in arrow  972 . As can be seen in  FIG. 10 , the fourth channel  966  is offset from the inlets  928  of the harborage device  900 . 
     As further shown in  FIG. 10 , the harborage device  900  includes the sensor  908  and an airflow device  910  to draw airflow toward the sensor  908  via the flow path. In the illustrative embodiment, the airflow device  910  is an air pump, such as, for example, a peristaltic or diaphragm pump. However, it should be appreciated that, in some embodiments, the airflow device  910  may be embodied as a compressor, a Micro-Electro-Mechanical-Systems (MEMS) device, or a fan. The sensor  908  and the air pump  910  are disposed in the top panel  904  of the harborage device  900  such that the sensor  908  and the air pump  910  are positioned in the inner chamber  940  of the harborage device  900 . The sensor  908  and the air pump  910  are positioned on the inner surface  926  of the top panel  904  such that, when the harborage device  900  is closed, the sensor  908  and the air pump  910  do not engage the plurality of the inner walls  916 , thereby avoiding interference with the airflow and/or the pest ability to move in the inner chamber  940 . In the illustrative embodiment, the air pump  910  is positioned between the outer frame  922  and the sensor  908  in order to draw air from the inlets  928  toward and through the sensor  908 . It should be appreciated that, in some embodiments, the air pump  910  may be omitted from the harborage device  900 . In such embodiments, the sensor  908  may rely on the natural airflow within the inner chamber  940  to deliver the targeted analyte secreted by the pests to the sensor  908  for detection. 
     In some embodiments, the sensor  908  may include a barrier sheet that covers the sensor  908 . The barrier sheet is made of a mesh material to prevent pests from coming in direct contact with the sensor  908 . It should be appreciated that the mesh material does not block diffusion of the targeted analyte. 
     As described above, the sensor  908  is configured to detect the presence of pests. For example, in the illustrative embodiment, the sensor  908  is embodied as a resonator sensor such as a quartz crystal microbalance (QCM) or a small-scale QCM sensor. As described in detail above, the resonator sensor  908  is configured to detect the presence of pests by detecting a presence of a targeted biochemical analyte secreted by pests in air. It should be appreciated that, in some embodiments, the sensor  908  may be embodied as a cantilever sensor to detect a presence of pests as described in detail above. It should also be appreciated that the sensor  908  may be any sensor described above in regard to  FIGS. 1-8 . 
     In some embodiments, the sensor  908  may be positioned outside of the harborage device  900 . In such embodiments, the sensor  908  is coupled to the harborage device  900  via a conduit, which is adapted to direct airflow from the harborage device  900  and feed air into the sensor  908  for detection. In some embodiments, an end of the conduit may be inserted up to 15 cm deep into the inner chamber  940  to create a draft-free environment in the inner chamber  930  to attract pests that avoid drafty locations (e.g., bed bugs). In some embodiments, the conduit may be inserted along one of the edges of the inner chamber  930 . In other embodiments, the conduit may be oriented at an angle up to 90 degrees relative to one of edges of the harborage device  900 . 
     It should be appreciated that, in some embodiments, the harborage device  900  may include a heating element to adjust the temperature in the inner chamber  940 . In such embodiments, the harborage device  900  may also include a controller to operate the heating element and maintain the temperature in the inner chamber  940  above ambient temperature up to 40° C. to create a favorable condition for the bed bugs. Additionally, in some embodiments, the controller may further increase the temperature to about 100° C. to exterminate any pests detected in the inner chamber  940 . In such embodiments, the controller may increase the temperature from the inlets  928  of the harborage device  900  toward the barrier wall  938  to about 100° C. in order to prevent the bed bugs within the inner chamber  940  from leaving the harborage device  900 . 
     In some embodiments, the harborage device  900  may further include a pre-concentrator that accumulates the targeted analyte and releases the accumulated targeted analyte for pest detection. The pre-concentrator may be embodied as one or more sheets that sorb targeted biochemical analyte that covers at least a portion of the inner surfaces  918 ,  926  of the harborage device  900  (e.g., one or more pathways from the inlets  928  to the sensor  908 ). For example, the one or more sheets may be made of an analyte-sorbing material or a woven or non-woven fibrous material. In some embodiments, the one or more fibrous sheets may contain sorbent powder between fibers of a sheet of fibrous material or between two sheets of a fibrous material for higher sorption. It should be appreciated that the pre-concentrator may be configured to sorb and accumulate the targeted analyte for a period of time and then release the accumulated targeted analyte all at once when heated to provide more concentrated targeted analyte for sensor detection. This reduces the diffusion of the targeted analyte to air space surrounding the pests and may allow the sensor  908  to detect the presence of fewer pests. 
     For example, the pre-concentrator may be configured to absorb the targeted analyte at a first temperature and release the absorbed targeted analyte at a second temperature. For example, in some embodiments, the pre-concentrator may be a fibrous material such as, for example, paper, which is filled with sorbent powder, and is positioned on at least one of the inner surfaces  918 ,  926 . In such embodiments, the pre-concentrator has a sorption phase and a desorption (i.e., release) phase. During the sorption phase, the heating element may be operated to increase the temperature inside of the harborage device  900  to above ambient temperature to attract pests, and the pre-concentrator is configured to absorb the targeted analyte secreted by the pests. During the desorption or release phase, the heating element is operated to further increase the temperature inside of the harborage device  900 , and the targeted analyte is desorbed or released from the pre-concentrator. The desorption of the targeted analyte increases the concentration of the targeted analyte drawn by the air pump  910  into the sensor  908  for pest detection. It should be appreciated that the sensor  908  may detect the presence of pests continuously or intermittently during the desorption phase. 
     In some embodiments, the pre-concentrator may be embodied as a tube or a column that extends from the inlet  928  of the harborage device  900  to the sensor  908 . In such embodiments, the tube is made of an analyte-sorbing material configured to sorb the targeted biochemical analyte as air surrounding the harborage device  900  passes through the tube. Upon heating the tube, the collected analytes in the tube are rapidly desorbed. It should be appreciated that the air pump  910  may facilitate to draw desorbed targeted analyte released from the pre-concentrator to the sensor  908  for detection. 
     In some embodiments, the harborage device  900  may include multiple heating elements. The heating elements may be uniformly distributed along the flow path to propagate heat pulses from the inlets  928  toward the sensor  908 . For example, the heating elements may be activated in an order, from a heating element farthest from the sensor  908  to a heating element closed to the sensor  908  or vise versa, to desorb the targeted analyte from the pre-concentrator in a sequence. Subsequently, the air pump  910  may be activated to pull air into the sensor  908 . When the fresh air is pulled in from the outside of the inner chamber  940  through the inlets  928  toward the sensor  908 , air collects the targeted analyte desorbed from the pre-concentrator in the inner chamber  940  and carries into the sensor  908  providing a higher concentration of the targeted analyte for pest detection. 
     It should be appreciated that the pre-concentrator may be lined along the peripheries of the harborage device  900 . In some embodiments, the pre-concentrator may be disposed adjacent to the sensor  908  opposite the air pump  910  such that the sensor  908  is positioned between the air pump  910  and the pre-concentrator. Such configuration allows the air pump  910  to draw desorbed targeted analyte released from the pre-concentrator to the sensor  908  for detection. In some embodiments, the sensor  908  may include an internal pre-concentrator. In some embodiments, the external pre-concentrator may be embodied as a test chamber sized to receive an amount of the targeted analyte. 
     In some embodiments, a barrier may be positioned between the outer frame  912  of the bottom panel  902  and the outer frame  922  of the top panel  904  when the harborage device  900  is in the closed configuration to prevent targeted analyte from diffusing out of the harborage device  900 . For example, the barrier may be embodied as a lining between the outer frames  912 ,  922  may be made of an aluminized film. Such barrier may increase a concentration of the targeted analyte in the harborage device  900  for the sensor detection. The barrier may further provide a preferable condition by establishing a draft-free zone inside the harborage device  900  to attract pests that avoid drafty locations (e.g., bed bugs). 
     Referring now to  FIGS. 12 and 13 , in use, the harborage device  900  is folded such that the outer frame  922  of the top panel  904  is positioned on top of the outer frame  912  of the bottom panel  902 . As discussed above, when the harborage device  900  is in the closed configuration, the inner surface  918  of the bottom panel  902  faces but spaced apart from the inner surface  926  of the top panel  904  defining the inner chamber  940 , which is configured to allow the pests to move in the inner chamber  940 . In the illustrative embodiment, the width of inner chamber  940  (i.e., the distance between the inner surface  918  of the bottom panel  902  and the inner surface  926  of the top panel  904 ) becomes smaller toward the sensor  908  to create a narrower flow path near the sensor  908  to increase the concentration of the targeted analyte near the sensor  908  by restricting the diffusion of the targeted analyte to the narrow path. However, it should be appreciated that, in some embodiments, the width of the inner chamber  940  may be consistent throughout the harborage device  900 . 
     As shown in  FIG. 13 , the bottom panel  902  further includes a plurality of ramp surfaces  920 , each of which is positioned outside of each inlet  928  to guide pests into the corresponding inlet  928 . In the illustrative embodiment, a width of each ramp surface  920  may range from 3 mm to 100 mm to correspond to the width of each inlet  928 . In some embodiments, the bottom panel  902  may include one ramp surface  902  that extends along an entire width of the bottom panel  902 . 
     As shown in  FIG. 9 , in the illustrative embodiment, the harborage device  900  is adapted to be positioned or secured to a bed headboard  952  of a bed  950  such that the bottom panel  902  is positioned between the surface of the bed headboard  952  and the top panel  904 . When the harborage device  900  is secured to the bed headboard, each ramp surface  920  is configured to bridge between the surface of the bed headboard  952  and each inlet  928  such that the pests may travel from the bed into the harborage device  900 . It should be appreciated that the ramp surface  920  may be coated with a textured material similar to the material on the inner surface  918  of the bottom panel  902  to provide pests traction to move upwardly along the ramp surface  920  into the harborage device  900 . In some embodiments, the ramp surface  920  may be colored to create a favorable condition to attract pests into the harborage device  900 . 
     In the illustrative embodiment, the harborage device  900  has a rectangular shape; however, it should be appreciated that the harborage device  900  may be in a polygon, a polygon with rounded corners, an oval, or a circle. It should be appreciated that external surfaces of the harborage device  900  may be in attractive color to attract pests. For example, the external surfaces of the harborage device  900  may be in red-shade or black color to attract bed bugs. It should also be appreciated that, in some embodiments, both bottom and top panels  902 ,  904  may be flat or curved to define the inner chamber  930  of harborage device  900 . In other embodiments, one of the panels may be flat and the other panel is curved to reduce the material used. 
     In the illustrative embodiment, the harborage device  900  further includes a local indicator. The local indicator is coupled to the sensor  908  via a wire and is positioned on the outer surface of the top panel  904  of the harborage device  900 . However, in some embodiments, the local indicator may be positioned outside of the harborage device  900  via a wire. In other embodiments, the local indicator may be wirelessly connected to the sensor  908  harborage device  900 . Similar to the local indicator  218  discussed in detail above, the local indicator may be embodied as any type of indicator that is capable of generating an alert to notify a human operator or a technician. For example, the local indicator of the harborage device  900  may be embodied as a visual and/or audible indicator. In some embodiments, the visual indicator may include a light emitting diode (LED), fluorescent, incandescent, and/or neon type light source. The audible indicator may generate an alert sound to notify the technician. In the illustrative embodiment, the local indicator generates an alert indicative of a presence or absence of bed bugs. For example, in some embodiments, the LED light indicator may be energized to project a colored light, change color, or change from a non-blinking light to a blinking light to indicate the presence of bed bugs. In other embodiments, the audible local indicator may generate sound to indicate the presence of bed bugs. 
     In other embodiments, the harborage device  900  may include a wireless communication circuit to communicate with a pest control system or server to notify when pests are detected and/or the sensor requires maintenance. As described in detail above, the wireless communication circuit may be configured to use any one or more communication technologies (e.g., wireless or wired communications) and associated protocols (e.g., Ethernet, Bluetooth®, WiMAX, LTE, 5G, etc.) to effect such communication. 
     In use, a human operator or a technician may mount the harborage device  900  on the bed headboard  952  of the bed  950  to detect the presence of the pests that have a preferred habitat near beds or mattresses, for example, bed bugs. The harborage device  900  is oriented such that the bottom panel  902  of the harborage device  900  is positioned on the surface of the bed headboard  952 . This allows the ramp surfaces  920  of the harborage device  900  to bridge between the surface of the bed headboard  952  and the inlets  928  to allow the pests to travel from the bed headboard  952  into the inner chamber  930  of the harborage device  900 . As discussed above, the ramp surface  920  may be colored or coated with a textured material to create a favorable condition to attract the targeted pests along the ramp surface  902  into the inner chamber  930 . 
     The air pump  910  of the harborage device  900  is continuously or periodically activated to pull air from the inlets  928  to draw the targeted biochemical analyte from area surrounding the pests in the inner chamber  930  toward the sensor  908 . When air is pulled into the sensor  908 , the sensor  908  is configured to detect the targeted biochemical analyte in air to detect the presence of the pests. For example, the sensor  908  is configured to detect the targeted biochemical analyte, such as T2H, T2O, 4-oxo-(E)-2-hexenal, and/or 4-oxo-(E)-2-octenal, to detect the presence of bed bugs in or near the harborage device  900 . The sensor  908  then transmits a signal to the local indicator to generate an alert to notify the human operator or the technician of the presence of bed bugs. 
     As described above, the harborage device  900  may not include any airflow devices, including, for example, an air pump  910 . Without an air pump  910  pulling air towards the sensor  908 , the sensor  908  relies on the targeted analyte present in the air surrounding the pests to reach the sensor  908  primarily via diffusion through air within the inner chamber  940 . In other words, the targeted biochemical analyte molecules spread away from the source (i.e., analyte-emitting bed bugs) in all available directions through air in the inner chamber  930  of the harborage device  900 . In such embodiments, the location of the sensor  908  in the inner chamber  940  may be selected to minimize the maximum diffusion path (e.g., an open passageway from the inlet  928  to the sensor  908 ). The harborage device may further include an impermeable liner (e.g., aluminized film) positioned in a gap between the outer frames  912 ,  922  of the top and bottom panels  902 ,  904 , respectively, to minimize the loss of the targeted analyte through the gap to maximize the concentration of the targeted analyte in the inner chamber  940  for the sensor detection. It should be appreciated that, in such embodiments, the harborage device may further include a pre-concentrator similar to the pre-concentrator described in detail above. In other embodiments, the harborage device may also include one or more heating elements similar to the heating element described in detail above. 
     Referring now to  FIG. 14 , another embodiment of a sensor  1000  is shown. Similar to the sensor  210 , the sensor  1000  includes a sensor cell  1002  (e.g., a quartz crystal resonator) and a sensor coating  1004  coated on the surface of the sensor cell  1002 . In the illustrative embodiment, the sensor coating  1004  includes a coating gel compound made of a polymer gel and the agent (e.g., dioctyl-CTI). As discussed above, the agent is configured to react with the targeted biochemical analyte  1006  found in the secretion of bed bugs (e.g., T2H, T2O, 4-oxo-(E)-2-hexenal, or 4-oxo-(E)-2-octenal). 
     In the illustrative embodiment, the polymer gel has high viscosity (e.g., a jelly-like consistency), optionally exhibits viscoplastic properties (e.g., yield stress), and high thermal and chemical stability to form a stable coating on the surface of the sensor  1002 . As such, rather than directly coating the agent onto the surface of the sensor  1002 , the polymer gel is adapted to form a medium to immobilize the agent on top of the surface of the sensor  1002 . Additionally, in the illustrative embodiment, a polymer gel that has a relatively low molecular weight was used to achieve a desired viscosity level of the polymer gel and increase the detection sensitivity of the targeted biochemical analyte, which is discussed further below. It should be appreciated that liquid to be used to dissolve polymer to form the polymer gel depends on a type of polymer to achieve a stable interface that has high thermal and chemical stability. An exemplary polymer gel may include polymethylphenylsiloxiane (PMPS), polydimethylsiloxane (PDMS), fluoroalcohol polycarbosilane which is available from Seacoast Science, Inc. of Carlsbad, Calif. and marketed as the SC-F101, fluoroalcohol polysiloxane which is available from Seacoast Science, Inc. of Carlsbad, Calif. and marketed as SXFA, bisphenol-containing polymer (BSP3), poly-2-dimethylamin-ethyl-methacrylate (PDMAEMC), or polymers with silicone (Si) and flourine (F). It should be appreciated that, in some embodiments, the coating gel compound may include more than one type of polymer gel. 
     In use, as shown in  FIG. 14 , the targeted biochemical analyte  1006 , typically in a gaseous state, present in the air surrounding the sensor  1000  diffuses into the coating gel compound of the sensor coating  1004 . The diffused targeted biochemical analyte  1006  then reacts with the agent present in the coating gel compound and produces an agent-targeted biochemical analyte product that has a higher molecular weight than the agent alone. In the illustrative embodiment, a low molecular weight polymer gel was used to form the coating gel compound, such that even a small weight change may be detected indicating a presence of a small amount of the targeted biochemical analyte  1006 . It should be appreciated that the diffused targeted biochemical analyte  1006  that has yet to react with the agent may be released back to the air based on solubility of the coating gel compound. 
     In the illustrative embodiment, the sensor coating  1004  was formed by spin coating to deposit uniform films to the surface of the sensor cell  1002  using a spin coater. To form a thin uniform coating, a thick layer of the coating gel compound was deposited onto the sensor cell  1002  and the excess of the coating gel compound was removed via centrifugal force exerted by spinning using a spin coater. In some embodiments, spray coating may be used to form the sensor coating  1004  by spraying a dosed amount of a mist of the coating gel compound onto the sensor cell  1002 . The mist may be produced by using an atomizing nozzle (e.g., piezoelectric or pressurized-gas-driven), an inkjet printing head (e.g., piezoelectric or thermal), or a similar device ejecting a single micro-drop of solution at a time. In other embodiments, the sensor coating  1004  may be formed by using a capillary deposition method, a soft lithography (e.g. microcontact printing), or a dip coating method. It should be appreciated that, in each of the embodiments, the coating gel compound may be diluted in a volatile solvent to control the viscosity of the coating gel compound during the coating process. 
     Referring now to  FIG. 15 , a graph illustrates a mass change of a coating gel compound that includes polydimethylsiloxane (PDMS) polymer gel and CTI agent. As discussed above, the mass change is caused by the reactions between the CTI agent in the PDMS coating gel compound and trans-2-hexenal (T2H) (i.e., the targeted biochemical analyte) present in the air surrounding the PDMS coating gel compound. Prior to introducing the targeted biochemical analyte, the temperature was increased to about 50 degree Celsius between t 0  and t 1  for about 110 minutes to ensure that the PDMS coating gel compound is clean. As discussed above, the reaction between the targeted biochemical analyte and the agent may be reversible with heat. By heating the PDMS coating gel compound at about 50 degree Celsius for about 110 minutes ensures that any possible targeted biochemical analyte reacted with the agent in the PDMS coating gel compound is removed from the PDMS coating gel compound. Additionally, any possible targeted biochemical analyte diffused in the PDMS coating gel compound that may not have reacted with the agent may also be released from the PDMS coating gel compound. 
     The temperature was dropped to about 35 degree Celsius at t 2  and was remained at about 35 degree Celsius. It should be noted that the weight of the PDMS coating gel compound remained relatively constant until the targeted biochemical analyte was introduced at t 3 . In other words, in the absence of the targeted biochemical analyte, no significant weight change in the PDMS coating gel compound that includes PDMS polymer gel and CTI agent was detected. 
     At t 3 , a sample with the targeted biochemical analyte was released into the air surrounding the PDMS coating gel compound until t 4 . The targeted biochemical analyte in the air surrounding the PDMS coating gel compound is adapted to diffuse into the PDMS coating gel compound based on the solubility of the PDMS coating gel compound. Once the targeted biochemical analyte is diffused in the PDMS coating gel compound, the targeted biochemical analyte is configured to react with the targeted biochemical analyte in the PDMS coating gel compound and produce an agent-targeted biochemical analyte product that has a higher molecular weight than the agent alone. Accordingly, as can be seen in  FIG. 15 , the weight plot continuously increased during the release of the targeted biochemical analyte from t 3  to t 4  indicating an increase in weight of the PDMS coating gel compound. 
     When the flow of the sample was stopped at t 4 , the weight of the PDMS coating gel compound slightly decreased. Such decrease in the weight may be caused by a release of unreacted targeted biochemical analyte from the PDMS coating gel compound. For example, the targeted biochemical analyte in the air surrounding the sensor  1000  may have diffused in the PDMS coating gel compound during t 3  and t 4  but has not yet to react with the agent in the PDMS coating gel compound. Such unreacted targeted biochemical analyte is adapted to diffuse out of the PDMS coating gel compound back to the surrounding air. Additionally, in some embodiments, the reaction between the agent and the targeted biochemical analyte may be reversible. In such embodiments, in the absence of the targeted biochemical analyte in the surrounding, the agent-targeted biochemical analyte products may be reversed back to the reactants (i.e., the agent and the targeted biochemical analyte) over time. 
     At t 5 , the sample with the targeted biochemical analyte was reintroduced to the air surrounding the sensor  1000  and the weight of the PDMS coating gel compound continued to increase again from the reaction between the targeted biochemical analyte of the sample and the agent in the PDMS coating gel compound. 
     Referring now to  FIG. 16 , a graph illustrates a mass change of another coating gel compound that includes polymethylphenylsiloxiane (PMPS) polymer gel and CTI agent. Similar to  FIG. 15 , the mass change is caused by the reactions between the CTI agent in the PMPS coating gel compound and trans-2-hexenal (T2H) (i.e., the targeted biochemical analyte) present in the air surrounding the PMPS coating gel compound. 
     Prior to introducing the targeted biochemical analyte, the temperature was increased to about 50 degree Celsius between t 0  and t 1  for about 110 minutes to ensure that the PMPS coating gel compound is clean. As discussed above, the reaction between the targeted biochemical analyte and the agent may be reversible with heat. By heating the PMPS coating gel compound at about 50 degree Celsius for about 110 minutes ensures that any possible targeted biochemical analyte reacted with the agent in the PMPS coating gel compound is removed from the PMPS coating gel compound. Additionally, any possible targeted biochemical analyte diffused in the PMPS coating gel compound that may not have reacted with the agent may also be released from the PMPS coating gel compound. 
     The temperature was dropped to about 35 degree Celsius at t 2  and was remained at about 35 degree Celsius. It should be noted that the weight of the PMPS coating gel compound remained relatively constant until the targeted biochemical analyte was introduced at t 3 . In other words, in the absence of the targeted biochemical analyte, no significant weight change in the PMPS coating gel compound that includes PMPS polymer gel and CTI agent was detected. 
     At t 3 , a sample with the targeted biochemical analyte was released into the air surrounding the PMPS coating gel compound until t 4 . The targeted biochemical analyte in the air surrounding the PMPS coating gel compound is adapted to diffuse into the PMPS coating gel compound based on the solubility of the PMPS coating gel compound. Once the targeted biochemical analyte is diffused in the PMPS coating gel compound, the targeted biochemical analyte is configured to react with the targeted biochemical analyte in the PMPS coating gel compound and produce an agent-targeted biochemical analyte product that has a higher molecular weight than the agent alone. Accordingly, as can be seen in  FIG. 16 , the weight plot continuously increased during the release of the targeted biochemical analyte from t 3  to t 4  indicating an increase in weight of the PMPS coating gel compound. 
     When the flow of the sample was stopped at t 4 , the weight of the PMPS coating gel compound slightly decreased. As discussed above, such decrease in the weight may be caused by a release of unreacted targeted biochemical analyte from the PMPS coating gel compound. For example, the targeted biochemical analyte in the air surrounding the sensor  1000  may have diffused in the PMPS coating gel compound during t 3  and t 4  but has not yet to react with the agent in the PMPS coating gel compound. Such unreacted targeted biochemical analyte is adapted to diffuse out of the PMPS coating gel compound back to the surrounding air. Additionally, in some embodiments, the reaction between the agent and the targeted biochemical analyte may be reversible. In such embodiments, in the absence of the targeted biochemical analyte in the surrounding, the agent-targeted biochemical analyte products may be reversed back to the reactants (i.e., the agent and the targeted biochemical analyte) over time. 
     At t 5 , the sample with the targeted biochemical analyte was reintroduced to the air surrounding the sensor  1000  and the weight of the PMPS coating gel compound continued to increase again from the reaction between the targeted biochemical analyte of the sample and the agent in the PMPS coating gel compound. 
     This disclosure further entails the composition, preparation, and use of the compounds exemplified by the below structures for use, for example, in bedbug detection. In particular, these compounds have shown in-solution reactivity with trans-2-hexanal, a chemical generated by bedbugs. The below compounds were synthesized and reactivity in solution with trans-2-hexanal (T2H) was tested by mixing a 1:1 ratio of phosphorodithioate with T2H. All the compounds reacted fully with T2H over time. 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
     Experimental Procedures 
     Synthesis of 2-mercapto-5,5-dimethyl-1,3,2-dioxaphosphinane 2-sulfide 
     
       
         
         
             
             
         
       
     
     A 250 ml R.B.F with magnetic stirrer bar was charged with the diol (5.0 g, 48.0 mmol), followed by P 2 S 5  (4.3 g, 19.3 mmol) and toluene (32 ml). Then the reaction mixture was heated to 100° C. for 12 h, under nitrogen. The mixture was cooled and concentrated under reduced pressure, a solid formed and was separated from the oil. The residual oil was concentrated under high-vacuum, pentane 50 mL was added and further dried under high-vacuum, to give 4.0 g of product.  1 H NMR (CDCl 3 , GLC=18743): δ 1.1 (s, 6H), 4.1 (J=15.5 Hz, 4H). 
     Synthesis of 2-mercapto-5,5-dipropyl-1,3,2-dioxaphosphinane 2-sulfide 
     
       
         
         
             
             
         
       
     
     Step 1: Synthesis of 2,2-dipropylpropane-1,3-diol 
     A 250 mL round bottom flask ( 1  neck) with magnetic stirrer bar was flame dried, cooled under vacuum, and then flushed with nitrogen. Under nitrogen, it was charged with diethyl 2,2-dipropylmalonate (5 g, 20.45 mmol) followed by THF (50 ml). The reaction was cooled to 0° C. and lithium aluminum hydride (27.6 ml, 27.6 mmol, 1M in THF) was added dropwise over 30 min, then reaction mixture was allowed to warm up to RT, stirred at RT for 3 hours. After this time, the reaction was cooled to 0° C. and water (1 ml) was added then 4 ml 15% NaOH (aq. solution), after 15 min of stirring the solid salts were filtered off and filtrate was dried over sodium sulfate, filtered and concentrated to obtain a colorless oil ˜2 g, which was purified by column (0-10% MeOH in DCM) to afford 2,2-dipropylpropane-1,3-diol 
     As an oil (1.1 g).  1 H NMR (CDCl 3 , GLC=18983): δ 3.52 (s, 4H), 3.15 (s, 2H), 1.21 (m, 8H), 0.89 (t, 6H) 
     
       
         
         
             
             
         
       
     
     Step 2: Synthesis of 2-mercapto-5,5-dipropyl-1,3,2-dioxaphosphinane 2-sulfide 
     A 50 ml R.B.F with magnetic stirrer bar was charged with 2,2-dipropylpropane-1,3-diol (1.1 g, 6.87 mmol), followed by P 2 S 5  (0.61 g, 2.75 mmol) in toluene (5 ml). Then the reaction mixture was heated to 100° C. for 16 h, toluene was distilled out at 100° C. under vacuum. The resulting residue was diluted in DCM and purified by column (0-100% DCM in hexane, isocratic gradient) to afford the title compound as greenish oil 0.6 g.  1 H NMR (CDCl 3 , GLC=19044): δ 4.13 (d, 4H), 2.62 (s, 1H), 1.32 (m, 8H), 0.95 (m, 6H). 
     Synthesis of 5,5-diisobutyl-2-mercapto-1,3,2-dioxaphosphinane 2-sulfide 
     
       
         
         
             
             
         
       
     
     A 250 ml R.B.F with magnetic stirrer bar was charged with 2,2-diisobutyl-1,3-propanol (2.0 g, 10.6 mmol), followed by P 2 S 5  (0.94 g, 4.23 mmol) and toluene (7 ml). Then the reaction mixture was heated to 80° C. for 3 h, under nitrogen. The mixture was cooled and concentrated under reduced pressure and purified by silica column (0-10% MeOH in DCM) to afford 0.9 g of the title compound.  1 H NMR (CDCl 3 , GLC=18768): δ 0.81-1.06 (m, 12H), 1.42 (d, J=5.5 Hz, 4H), 1.73 (m, 2H), 2.93 (s, 1H), 4.17 (d, J=15.7 Hz, 4H). 
     Synthesis of O,O-bis(2-methoxyethyl) S-Hydrogen Phosphorodithioate 
     
       
         
         
             
             
         
       
     
     A 50 ml R.B.F with magnetic stirrer bar was charged with 2-methoxyethanol (4.2 mL, 52.0 mmol), followed by P 2 S 5  (2.8 g, 12.6 mmol) and toluene (50 ml). Then the reaction mixture was heated to 80° C. for 4 h, and was concentrated under reduced pressure. The resulting residue was diluted with minimal DCM and purified by column (40-80% ethyl acetate in hexane) to afford the title compound as greenish oil 1.2 g.  1 H NMR (CDCl 3 , GLC=19229): δ 4.30 (m, 4H), 3.66 (m, 4H), 3.4 (s, 6H). 
     Synthesis of O,O-bis(4-methylpentan-2-yl) S-Hydrogen Phosphorodithioate 
     
       
         
         
             
             
         
       
     
     A 250 ml R.B.F with magnetic stirrer bar was charged with the alcohol (6.0 mL, 47.0 mmol), followed by P 2 S 5  (3.0 g, 13.5 mmol) and toluene (31 ml). Then the reaction mixture was heated to 100° C. for 12 h, under nitrogen. The mixture was cooled and concentrated under reduced pressure, and 3.0 g of the mixture was further dried under high-vacuum, to give 1.1 g of the title compound.  1 H NMR (CDCl 3 , GLC=18843): δ 0.91 (m, 12H), 1.37 (m, 8H), 1.68 (m, 4H), 4.8 (m, 2H). 
     Synthesis of O,O-Dipentyl S-Hydrogen Phosphorodithioate 
     
       
         
         
             
             
         
       
     
     A 50 ml R.B.F with magnetic stirrer bar was charged with 1-pentanol (1.1 mL, 10.1 mmol), followed by P 2 S 5  (0.56 g, 2.5 mmol) and toluene (12.5 ml). Then the reaction mixture was heated to 100° C. for 3 h, under nitrogen. The resulting residue was cooled to RT and a 50% w/v solution of KOH was added. The mixture was concentrated under reduced pressure, a semi-solid was crystallized and was washed with hexane to give the 0.5 g of the title compound.  1 H NMR (CDCl 3 , GLC=19169): δ 0.91 (m, 6H), 1.37 (m, 8H), 1.71 (m, 4H), 4.15 (m, 4H). 
     While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. 
     There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatus, and system described herein. It will be noted that alternative embodiments of the method, apparatus, and system of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the method, apparatus, and system that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure as defined by the appended claims.