Abstract:
Conveying systems and method for detecting the presence and amount of biological contaminants or additives on a conveyor belt. The conveyor system includes a conveyor belt having embedded biosensors. Transmitters co-located in the belt with the biosensors transmit biosensor signals to a remote controller. The remote controller allows remote monitoring of the contamination level on the conveyor belt.

Description:
BACKGROUND 
     The invention relates generally to power-driven conveyors conveying articles and more particularly to conveyor belts with embedded biosensors and methods of detecting biological contaminants or additives on conveyor belts. 
     Biological contamination or improper levels of additives can compromise the quality and safety of food products. In many applications, food products are conveyed through continuous processes on a conveyor belt. Typical methods of detecting the presence of biological contaminants or additives on food products include the steps of taking samples of the food products or of food fluids, rinse water, or other specimens that come in contact with the food products, culturing those samples in a Petri dish, and observing the culture under a microscope. Those steps rely to a great degree on human participation and can be time-consuming. 
     SUMMARY 
     These shortcomings are overcome by a conveying belt embodying features of the invention. One version of such a conveyor belt comprises a biosensor that advances along a conveyor path with the conveyor belt, senses the presence of a predetermined analyte, and produces a corresponding response signal. 
     In another aspect of the invention, a conveying system embodying features of the invention comprises a conveyor belt that includes a biosensor sensing the presence of a predetermined analyte and producing a corresponding response signal and a transmitter transmitting the response signal. A receiver remote from the conveyor belt receives the response signal transmitted by the transmitter. 
     Another version of a conveying system embodying features of the invention comprises a conveyor belt that includes a biosensor sensing the presence of a predetermined analyte and a biosensor-loading-unloading device for loading and unloading the biosensor in the conveyor belt. 
     Yet another version of a conveying system embodying features of the invention comprises a conveyor belt having an outer surface atop which articles are conveyed along a carryway. A scraper has a scraping end that contacts the outer surface of the conveyor belt off the carryway to scrape residue from the outer surface. A collector is positioned to receive the residue scraped from the outer surface of the conveyor belt by the scraper. A biosensor disposed in the collector senses the presence of a predetermined analyte and produces a corresponding response signal. 
     In another aspect of the invention, a method for monitoring a process for contamination of articles conveyed continuously through the process on a conveyor belt comprises: (a) advancing articles supported on a conveyor belt along a conveyor path; (b) detecting a predetermined analyte at an outer surface of the conveyor belt with a biosensor mounted in and advancing with the conveyor belt and producing measurements; and (c) transmitting the measurements remotely from the conveyor belt to a monitoring station. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These aspects and features of the invention are better understood by referring to the following description, appended claims, and accompanying drawings, in which: 
         FIG. 1  is an isometric view of a conveyor system embodying features of the invention including a conveyor belt with biosensors; 
         FIG. 2  is a block diagram of the conveyor system of  FIG. 1 ; 
         FIGS. 3A and 3B  are axonometric views of a conveyor belt module with an embedded biosensor usable in a conveyor belt as in  FIG. 1  showing the biosensor before and after installation; 
         FIG. 4  is an isometric view of a portion of a flat belt with an attached biosensor usable in a conveyor system as in  FIG. 1 ; 
         FIG. 5A  is top plan view of a biosensor-loading-unloading device usable with a conveyor system as in  FIG. 1 , and 
         FIG. 5B  is a cross-sectional view of the biosensor-loading-unloading device viewed along  5 B- 5 B of  FIG. 5A ; and 
         FIG. 6  is an isometric view of another version of a conveyor system embodying features of the invention including a biosensor disposed in a tray in which residue scraped from a conveyor belt is collected. 
     
    
    
     DETAILED DESCRIPTION 
     One version of a conveyor system embodying features of the invention is shown in  FIG. 1 . A conveyor, shown in this example as a conveyor belt  10 , carries articles  12  on an outer surface  22  along a carryway segment  15  of the belt&#39;s endless conveyor path. For example, the conveyor belt  10  may carry articles such as vegetables, fruits, poultry, meat, fish or other raw or processed foodstuffs along the carryway  15 . At the end of the carryway, the articles are conveyed off the conveyor belt. After rounding drive sprockets  18 , the conveyor belt  10  follows a return segment  17  on its way back around idle sprockets  20  to the carryway segment  15 . 
     One or more biosensors  24  disposed in or on the belt  10  are set to detect one or more analytes that may be contaminating or degrading the articles and to provide a response to the presence of a predetermined analyte. In this example, which shows a modular plastic conveyor belt constructed of rows of hinged modules, the biosensors are shown at spaced apart locations along the length of the belt and across its width. The sensors open onto the belt&#39;s outer surface  22  on which fluids, fats, and other specimens from the articles that could contain contaminants or additives would reside. Examples of analytes present in the specimens that may be selectively sensed by the biosensors include: pathogenic microorganisms, contaminants, additives, degradation products, chemical markers of microbial infestation, bacteria, bacterial endotoxins, mycotoxins, botulism, food poisoning,  streptococcus, E. coli., salmonella , cholera, protozoan pathogens,  staphylococcus , viruses, and fungi. 
     As shown in  FIG. 2 , each biosensor is connected to a logic circuit  28  in the conveyor belt  10 . Each logic circuit may be realized by a programmed microcontroller or by hardwired logic elements. Conventional signal-conditioning circuit components, such as buffers, amplifiers, analog-to-digital converters, and multiplexers, may be interposed between the biosensors and the logic circuit. The logic circuit may also include a unique address or other identifying indicia to correlate the response of each biosensor with a specific sensor position on the conveyor belt. The identifying indicia and the biosensor response may be stored in one or more memory elements  29 . The biosensor, which may include an integral or an external transducer, produces a response that is converted into a biosensor signal  30  that is transmitted remotely by a transmitter  32 . The transmitter may be a wireless RF transmitter transmitting wirelessly via an antenna  34  over a wireless communication link  36  or over an ohmic connection  38  between a conductive contact  40  on the outside of the belt  10  and a brush  42  in conveyor structure along the side of the belt, as in  FIG. 1 . A receiver  33  may also be connected to the logic circuit to receive command and control signals from a remote controller  44 , i.e., a controller not located on or in the conveyor belt. Other transmitter-receiver technologies, such as optical or infrared, for example, may be used. All the components embedded in the belt may be powered by a power source  45 , such as one or more battery cells, housed together in a cavity in the belt. Alternatively, the power source  45  may be an energy harvester harvesting energy from vibratory motion or articulation of the conveyor, thermal gradients, or other energy-producing effects inherent in the process or conveyance. The embedded power source  45  may alternatively be powered by induction or by RF charging as it recirculates past an external charging device  49 , as in  FIG. 1 . 
     A remote receiver  46  receives the biosensor signal  30  via an antenna  48  over the wireless communication link  36  or over the ohmic connection  38  from the receiver  33  embedded in the conveyor belt. The receiver  46  sends the biosensor signal to the remote controller  44 . A transmitter  47  connected between the controller  44  and the antenna  48  or the ohmic connection  38  may be used to send command and control signals to the belt-borne biosensor circuits. An operator input device  50  connected to the controller  44  may be used to select biosensor or alarm settings or displayed data. From the settings and the biosensor response to, for example, the level of a certain additive, the controller adjusts an additive supplier  26  to correct the level of the additive to within an optimum range. The controller  44  may also be used to control the speed of the motor  52  driving the drive sprockets or to stop the conveyor. A video display  54  may be used to monitor system operating conditions and settings or display alarm conditions. A more clearly visible or audible alarm  56  may also be used by the controller to warn of irregularities in the process, such as the amount of analyte exceeding a predetermined level. The controller may be a programmable logic controller, a laptop, a desktop, or any appropriate computer device. 
     One version of a biosensor is a microelectromechanical (MEMS)-based impedance biosensor  58  in chip form as shown in  FIGS. 3A and 3B . The MEMS-based biosensor comprises a silicon chip with interdigitated electrodes in the form of parallel rows of electrodes  60  and an exterior sensing surface  62 . When a predetermined analyte, such as  E. coli  O157:H7 bacteria, binds to the sensing surface, the impedance between the electrodes changes with the concentration level of the analyte. When the sensor applies a known voltage across the electrodes, the change in impedance is measured as a change in current, which is the biosensor&#39;s response to the presence of the predetermined analyte (in this example,  E. coli .). The signal-conditioning circuitry in the biosensor converts the response into the biosensor signal  30  that is transmitted off the belt and compared to an impedance-level setting by the remote controller  44  ( FIG. 2 ) to determine the concentration of analyte and sound the alarm  56 , stop the conveyor belt  10 , adjust the injection of additives, or take whatever course of action had been prescribed. The signal-conditioning circuitry, logic circuitry, transmitter, antenna, and other related components composing the biosensor&#39;s support circuitry  64  are co-located with the biosensor  58 . A sensing belt module  66  having a cavity  68  opening onto a top surface  70  of the module holds the biosensor  58  with its sensing surface  62  flush with the top surface  70  of the module. The sensing belt module may be connected side to side with other sensing modules or with standard modules without sensors to form belt rows and the rows connected hingedly end to end to realize the conveyor belt  10  of  FIG. 1  as a modular conveyor belt. The belt modules are made, for example, of a thermoplastic polymer material in an injection-molding process. The biosensor  58  can be retained in the cavity  68  by adhesives or by mechanical means, such as snap-lock retention structure, lids or other retainers affixable to the module, or by suction cups. 
     The conveyor belt in  FIG. 1  is alternatively realized as a flat belt  72 , with or without drive elements on the inner side, as in  FIG. 4 . In this version of conveyor belt, the biosensors  58  are affixed to the outer surface  74  of the belt by bolts, screws, rivets, adhesives, or other fasteners. But the biosensors or their support circuits could alternatively be molded or extruded into the belt during manufacture. 
       FIGS. 5A and 5B  show a belt sensor module  76  similar to the module  66  shown in  FIGS. 3A and 3B . A cavity  78  for the biosensor has an opening  80  onto an outer side  82  of the module  76 . Adjacent to the outer side  82  of the belt module is a biosensor-loading-unloading device  84 , which houses a stack  86  of biosensors  58 . A coil spring  88  biases the stack  86  of biosensors  58  resting on a spring plate  87  upward toward a loading position  89 , from which the biosensor  58  can be automatically loaded into the cavity  78  in the belt module. A pneumatic actuator  90  with a pushing member, or push rod  92 , pushes the biosensor  58  at the top of the stack into the cavity  78  through the opening  80  in the outer side  82  of the module  76 . Other linear actuators, such as hydraulic, electromagnetic, or electromechanical, may be used instead to load the biosensor into the sensing position. The controller  44  ( FIG. 2 ) can control the actuator to load biosensors according to a predetermined set schedule. The sensing module  76  and any other belt modules across the belt row may also have lateral passageways  94  communicating with the cavity  78 . With an elongated pushing member, the actuator  90  can be used unload the biosensor by pushing it from the cavity through the laterally aligned passageways and out the opposite side of the belt into a drop box  96  for collection. Thus, the loading and unloading of biosensors can be easily coordinated by using the same actuator to move the biosensors into or out of the conveyor belt. Of course, the actuator can be used for loading the biosensor into the cavity with unloading performed manually or by some other means. 
     As shown in  FIG. 6 , a biosensor  58  is disposed in a collector  98 , such as a tray. A scraper  100 , which has a scraping end  102 , or blade, contacting the outer surface  104  of a conveyor belt  106  as it wraps around a sprocket or pulley set (not shown). Residue on the conveyor belt  106  is scraped from the outer surface  104  by the scraper  100  and directed into the collector tray  98 . The biosensor  58  detects the presence and amount of a predetermined analyte in the residue scraped from the conveyor belt. Alternatively, the biosensor  58  can be embedded in the scraper  100 . 
     Although the invention has been described in detail with respect to a preferred version, other versions are possible. For example, the sensing portion of the biosensor could be housed in a separate carrier from the support circuitry so that the biosensor can be replaced without replacing the rest of the circuitry. The rest of the circuitry can be made a permanent part of the belt by integrally molding or extruding it with the belt or by potting it in a belt cavity. As another example, the biosensors depicted in the examples are shown with their sensing surfaces at left and right sides of the belts. But they could be positioned anywhere across the width of the belts, in the underside of the belt, or in the hinge area of the modular belts depending on the best position to encounter the specimens. The remote controller provides the flexibility to take many kinds of actions in response to an excessive amount of analyte. Besides those actions mentioned, the controller could: schedule later production runs for more frequent testing; sound different levels of alarms depending on the severity of the contamination; initiate remedial or prophylactic actions, such as sanitizing, dumping, and reprocessing, in the process; provide more remote monitoring of the process via Internet, cell system, or satellite relay; or send remote alarms via various alert systems, such as text messaging, email, or pager signal. So, as these few examples suggest, the scope of the claims is not meant to be limited to the details of the example versions used to describe features of the invention.