bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Tin Oxide in the Field of Wearable Technology
Authors: Arya Sandeep , Sharma Asha , Singh Anoop , Khosla Ajit
Published: July 2021

Escalating rapidity in the technology leads to the exploration of wearable and mobile devices. There is paramount importance of wearable technology for health management as diseases can be timely monitored which in turn circumvent severe medical situations and decrease economic losses. Wearable technology involves the integration of electronic components into textiles or fabrics for wide range of applications including sensors, medical devices and safety instruments [1, 2]. Textiles, owing to their flexible and capillary characteristic, hold imperative position in the fabrication of rapid and inexpensive point-of-care sensing devices [3]. Metal oxides are affirmed to have potential applications in the fabrication of wearable sensors because of their unique electrical, electrochemical and biocompatible properties. With high surface to volume ratio, the sensitivity, selectivity and catalytic activity of metal oxide semiconductors is greatly enhanced. They serve as excellent candidates for the next generation of wireless sensing and online monitoring applications due to the fast response and long lifetime in different environmental conditions. Among the metal oxide semiconductors, SnO2 is considered as one of the important material due to their number of properties, like biocompatibility, anti-oxidant , anti-bacterial, cytotoxic properties, strong physical and chemical interactions with adsorbed species, high degree of transparency in the visible spectrum, low operating temperature etc. [4]. There is an increased usage of SnO2 as modifier electrode materials because of its astonishing features of thermal stability, biocompatibility, excellent bandgap, cost effective and abundant availability. The surface of working electrode is modified by nanomaterials of SnO2 in combination with various metals, semiconductors and carbon derivatives for improved sensing performance. As per the recent reports, tin oxide in find its applications in the field of glucose sensing [5], gas sensing [6], monitoring heavy metals [7], phenol sensing [8] etc. Apart from the reported applications, tin oxide is proved to be a useful candidate in stealth technology [9].

References

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Li, J. Tian, W. Shen, ACS Appl. Mater. Interfaces 2 (2010) 1.

Vidhu, D. Philip, Spectrochim. Acta, Part A 134 (2015) 372.

Sedighi, M. Montazer, S. Mazinani, Biosens. Bioelectron. 135 (2019) 192.

Wang, C. Zhao, T. Han, Y. Zhang, S. Liu, T. Fei, S. Liu, T. Zhang, Sens. Actuators, B 242 (2017) 269.

Wei, C. Gao, F.L. Meng, H.H. Li, L. Wang, J.H. Liu, X.J. Huang, J. Phys. Chem. C 116 (2011)1034.

Guo, P. Cai, , J. Sun, W. He, X. Wu, T. Zhang, X. Wang, Carbon 99 (2016) 571.

M Jeong, J. Ahn, Y. K. Choi, T. Lim, K. Seo, T. Hong, G. H. Choi, H. Kim, B. W. Lee, S.Y. Park, S. Ju, NPG Asia Materials 12 (2020) 32.
Explosives Trace Detector (ETD) Testing
Authors: Choi Young , Sunderman Michelle , Glasbrenner David , Howard Meg , Dean Stacy , Middleton Jason
Published: July 2021

The QS-B220 Explosives Trace Detector (ETD; Implant Sciences Corporation, Wilmington, MA, USA) was tested to determine whether Sample Traps (Impant Sciences Part No. 42200191 REV) contaminated with severe acute respiratory syndrome coronavirus (SARS-CoV-2) can be effectively decontaminated for re-use during normal operation. Sample Traps were inoculated with a known concentration of SARS-CoV-2 (strain USA-WA1/2020), allowed to dry at ambient conditions, and inserted into the QS-8220 ETD’s Sample Desorber (i.e., the sample port). During normal operation, heat is generated and directed at the Sample Trap undergoing analysis, and it was the heating process that was evaluated for decontamination efficacy against the virus. Each Sample Trap was inserted into the QS-8220 ETD at least two times (constituted a single exposure) to ensure that it was completely heated. Multiple exposures were tested, but it only took a single exposure inside the QS-8220 ETD to result in no recoverable infectious SARS-CoV-2 (based on the 1.31 × 101 median tissue culture infectious dose [TCID50] limit of detection) and expressed as 5.29 log reduction from the Sample Traps.
Reagentless and Ultrasensitive Electrochemical Dnazyme Based Sensing Platform for Clinical Detection of Uropathogenic Escherichia coli
Authors: Pandey Richa , Chan Dingran , Li Yingfu , Soleymani Leyla
Published: July 2021

Urinary tract infections (UTIs) are one of the most ubiquitous bacterial infection diseases affecting half of the global population at least once in their lifetime. Given the occurrence of the false positive result in dipstics and the time-consuming identification of bacteria using culturing method to detect UroPathogenic Escherichia coli (UPEC), there is the need for a point-of-care diagnostic platform that is reliable, sensitive, specific, cost-effective, fast and easy to use. With the advent electrochemical methods coupled with the specific biorecognition elements, the detection of any biomarker has become possible with one touch. Among many biorecognition molecules, DNAzymes are gaining attention due to their robustness, stability, specificity, and the ease of selection without prior knowledge of the biomarker. Their structure switching and functionality (RNA cleaving) can be utilized with redox active species (like methylene blue) to design highly sensitive and selective electrochemical assays for pathogen detection. In this work, we have developed a dual signaling electrochemical DNAzyme based platform for specific and sensitive detection of Escherichia coli (E.coli) in UTI patient urine samples. The two on-chip integrated working electrodes named as release channel and capture channel are integrated with DNAzyme-redox barcode and DNA probe respectively. In the presence of the bacterial target the DNAzyme catalyzes the cleavage of the redox DNA barcode in the release channel, which is subsequently translated into a redox signal upon hybridization with the probe on the capture channel. The differential signal generated by the two channels in the sensor demonstrated the sensitive detection of 10 CFU for E.coli in buffer and urine. Additionally, the sensor specifically detected E. coli in the presence of a panel of other gram positive and negative bacteria. Clinical validation of the assay was performed using 45 E.coli+ and E.coli- patient urines delineating a clinical sensitivity of 100% and specificity of 78% in a 30 minute testing time. This cost effective, reagent-free, time-efficient, and amplification-free electrochemical assay is suitable for detecting a wide range of pathogens, also alleviates the additional knowledge requirement of the biomarker as compared to other protein and aptamer-based assay. With the advancement in the chip fabrication and microfluidics, this assay can also be multiplexed with other pathogen for simultaneous detection of multiple pathogens in a single urine sample.
3D Printed Hydrogel-Based Sensors for UV Sensing Applications
Authors: Finny Abraham Samuel , Jiang Cindy , Andreescu Emanuela
Published: July 2021

The development of additive manufacturing techniques to manufacture sensors rapidly and cost-effectively would benefit healthcare, environmental monitoring, food, and cosmetic industries. Because of the inherent complexity of sensing devices, new fabrication methods that utilizes recent advances in additive manufacturing to create sensors on a large scale efficiently are necessary. Techniques like 3D printing and 3D bioprinting enable printing different biomaterials into intricate 3D architectures that could serve as sensing platforms. This presentation will describe 3D printed hydrogel-based sensors’ development and optimization with incorporated receptor molecules and transduction interfaces for UV sensing1. To 3D print these sensors, an extrusion-based 3D bioprinter and a computer-aided designing software were used along with a novel bio-ink formulation. The bio-ink formulation contains nanoparticles with photocatalytic properties and degradable dyes dispersed homogeneously within a mechanically stable hydrogel network. The optimum hydrogel composite provides excellent mechanical properties to the printed sensors, enabling them for many applications. The proposed sensors are reagent-less and highly portable, making them ideal for wearable devices and printed platforms for portable bioelectronics. Apart from their ability to be used as wearable sensors, these sensors also have the potential to be used simultaneously with UV-based workspace sterilizing devices to guarantee that surfaces are adequately exposed to UV. The sensors are cheap, durable, robust, biodegradable, and simple to use. The tunable, biocompatible, and printable properties of the ink offer great potential for developing advanced 3D printing methods that, in addition to UV sensors, can be applied more broadly to fabricate other sensing technologies for various other applications.

1. A. S. Finny, C. Jiang, and S. Andreescu, ACS Applied Materials & Interfaces, 12, 43911–43920 (2020).

Figure 1
(Plenary) Wearable Sensors for Monitoring Chemical Markers: Beyond Steps and Vitals
Authors: Wang Joseph
Published: July 2021

Wearable sensors have received a major recent attention owing to their considerable promise for monitoring the wearer's health and wellness. The medical interest for wearable systems arises from the need for monitoring patients over long periods of time. These devices have the potential to continuously collect vital health information from a person's body and provide this information to them or their healthcare provider in a timely fashion. Unlike early efforts aimed at monitoring mobility and vital signs, our recent efforts aim at filling the gaps by providing continuous biochemical information. The new chemical sensing wearable platforms provide new avenues to continuously and non-invasively monitor individuals and can thus tender crucial real-time information regarding a wearer's health. This presentation will discuss recent developments in the field of wearable electrochemical sensors integrated directly on the epidermis or within the mouth for various non-invasive biomedical monitoring applications [1-3]. Particular attention will be given to non-invasive monitoring of metabolites and electrolytes using flexible amperometric and potentiometric sensors, respectively, along with related materials, energy and integration considerations. Microneedle sensor arrays for multiplexed ISF monitoring will also be discussed also with wearable energy harvesters aimed to power these devices. The preparation and characterization of such wearable electrochemical sensors will be described, along with their current status and future prospects and challenges.

REFERENCES

[1] "Wearable Chemical Sensors: Present Challenges and Future Prospects" A. J. Bandodkar, I. Jeerapan, J. Wang, ACS Sensors, 2016, 1, 464.

[2] A. J. Bandodkar and J. Wang, "Non-invasive wearable electrochemical sensors: a review", Trends Biotechnol., 2014, 32, 363.

[3] "Wearable biosensors for healthcare monitoring", J. Kim, A. S. Campbell, B. Esteban-Fernández de Ávila, and J. Wang, Nature Biotechnology, 2019, 37, 389.
(Invited) Fabric Pressure Sensors for Longitudinal Monitoring of Human Motion in Natural Environments
Authors: Andrew Trisha L.
Published: July 2021

Apparel with embedded self-powered sensors can revolutionize human behavior monitoring by leveraging everyday clothing as the sensing substrate. The key is to inconspicuously integrate sensing elements and portable power sources into garments while maintaining the weight, feel, comfort, function and ruggedness of familiar clothes and fabrics. We use reactive vapor coating to transform commonly-available, mass-produced fabrics, threads or premade garments into comfortably-wearable electronic devices by directly coating them with uniform and conformal films of electronically-active conjugated polymers. By carefully choosing the repeat unit structure of the polymer coating, we access a number of fiber- or fabric-based circuit components, including resistors, depletion-mode transistors, diodes, thermistors, and pseudocapacitors. Further, vapor-deposited electronic polymer films are notably wash- and wear-stable and withstand mechanically-demanding textile manufacturing routines, enabling us to use sewing, weaving, knitting or embroidery procedures to create self-powered garment sensors. We will describe our efforts in monitoring heartrate, breathing, joint motion/flexibility, gait and sleep posture using loose-fitting garments.
(Invited) Eight Channel Microphysiometry Using a Lab on a Chip Microclinical Analyzer
Authors: Cliffel David , Melow Sara , Miller Dusty , Tuladhar Pragun
Published: July 2021

We have built a multianalyte microphysiometer that detects multiple analytes involved in the cellular bioenergetics simultaneously. Monitoring the uptake of glucose and oxygen, and the production of lactate and acid gives a more complete picture of the metabolic processes within the cell than just acidification microphysiometry alone. Metabolic processes such as glycolysis, mitochondrial ATP generation, and glycogenesis are all directly related to the flux of these analytes. Temporal resolution of metabolic responses is much faster than conventional well-plate studies, leading to dynamic metabolic data. Electrochemical sensors are easily adapted into microfluidic formats for microphysiology readouts.

Our newest instrumental designs include a complete overhaul of the microfluidic chambers, screen printed electrodes, and microfluidic pumps, valves, and drivers that will enable easy adoption of this methodology in the development of 3D cell and tissue studies using 8 separate electrochemical measurements at a time. In the first design, 8 separate amperometric sensors are developed using a screen printed electrode with isolated microfluidic channels. In the second design, 4 amperometric sensors are combined with 4 potentiometric sensors using the newly created CH1440 created by CH Instruments. The adaption of this technology to instrumenting organs-on-a-chip is currently underway.
Highly Sensitive and Selective Non-Enzymatic Measurement of Glucose Using Arraying of Two Sweat Sensors Modified By Controlled Growth of Co/Cu and Functionalized Carbon Nanotubes
Authors: Eslami Reza , Azizi Nahid , Ghaffarian Reza , Mehrvar Mehrab , Zarrin Hadis
Published: July 2021

Due to a relation between glucose in sweat and blood, there is an opportunity to monitor patients' glucose levels non-invasively through sweat. There is a high demand for developing highly selective and sensitive biosensors in order to sense biomarkers like glucose and, therefore, the diseases based on those biomarkers. However, enzymatic sensors are selective to specific biomarkers; they are suffering from high sensitivity to the fluctuation of temperature, oxygen, pH, humidity, detergents, organic reagents, and toxic chemicals, affecting their stability and sensitivity, and reproducibility. Therefore, developing non-enzymatic glucose (or other biomarkers) sensors is getting significant attention to fulfill higher sensitivity and selectivity as well as minimized susceptibility to fouling by enzyme-ageing and adsorbed intermediates. Here we have proposed a combination of two sensors that can help us improve these non-enzymatic sensors' selectivity. Two electrochemical arrayed sensors have been developed. The first electrochemical sensor has been achieved by controlled growth of cobalt nanowire and copper nanoparticles on carbon substrate in order to measure the glucose level at low concentrations, and the second electrochemical sensor has been modified by MWCNT-CO-NH-cyanuric-NH2 and Fe3O4 in order to measure the uric acid and eliminate the interference of it in glucose measurement results. In order to show the morphology of the glucose sensor, the SEM and EDX have been conducted. Also, the FT-IR test has been shown to confirm the functionalization of MWCNT. The electrocatalytic and electrochemical performance of each sensor have been evaluated in the presence of the various contaminants of sweat. The glucose sensor showed less than 5% interference toward ascorbic acid, sodium bicarbonate, and the lactic acid at their max range of presence in the sweat. For eliminating the interference of uric acid, the second sensor has developed, which has no response to the glucose and high sensitivity to the uric acid. The calibration curve of each sensor has been provided in the 3D form, and a simple method of arraying has been applied to improve the sensors' selectivity. The arrayed sensors showed a highly glucose-selective sweat-based sensor with minimized error imposed by the uric acid interference. The glucose sensor's reproducibility and durability have also been tested, which showed less than 5% and 10% variations, respectively. In the end, the arrayed sensor's performance has been evaluated by real sweat samples of a male and a female, analyzed by Clarke’s error grid analysis showing less than 20% deviation from the glucose levels measured by the commercial glucometers.
(Invited) The New Paradigm in Passive Sweat Wearables: Temporal Profiling of Biomarkers to Elucidate the Relationship between Stress and Inflammation in Passively Expressed Eccrine Sweat
Authors: Prasad Shalini , Lin Kai-chun , Jagannath Badrinath , Pali Madhavi , Upasham Sayali , Bhide Ashlesha , Sankhala Devangsingh , Muthukumar Sriram
Published: July 2021

When the body is under stress, a lot of physiological processes work towards bringing the body back to its normal state. Cortisol, a stress hormone and TNF-alpha, a protein related to inflammation, are direct products of these physiological processes. The goal of this work is the demonstration of a biosensor that is capable of tracking these molecules in human sweat. The significance lies in simplifying chronic disease diagnostics, i.e. technique used to detect and monitor diseases in a non-invasive manner. This system is designed to be a wearable device that will track those physiologica process and use cortisol and TNF-alpha levels as indicators of user’s health status.

Background: The HPA (Hypothalamic-Pituitary-Adrenal) axis is involved in maintaining homeostasis by engaging with the parasympathetic nervous system. During the process of chronic disease affliction to the body, this relationship is disturbed and there is an imbalance driven response observed with creation of disease related symptoms. This is of prime clinical importance when the body is chronically exposed to high levels of stress. By monitoring the two key components, cortisol, a direct product of the HPA axis and TNF-alpha, a pro-inflammatory cytokine, the manifestations of chronic stress on the homeostasis and diseased state of the body can be evaluated in a holistic/comprehensive manner. Materials and Methods: This work describes a novel sweat based sensing system which uses electrochemical modality to perform detection of cortisol and TNF-alpha. Results and Conclusion: This work highlights the development of an electrochemical detection system for the two biomarkers through human sweat. Limit of detection of the system is 1 ng/ml for cortisol and 1 pg/ml for TNF-alpha and dynamic range is 1-200ng/ml and 1-1000 pg/ml for cortisol and TNF-alpha respectively. This wearable system is designed to be a point of use, patient centric, chronic disease self-monitoring and management platform.
Effect of Temperature on Methanol and Ethanol Measurement Using Noble Metal Doped Tin Oxide Sensors
Authors: Sun-Kou Rosario , Paredes-Doig Ana , Picasso Gino , La Rosa-Toro Adolfo , Doig-Camino Elizabeth
Published: July 2021

In this work, the results of the sensing assays using the sensors based on tin oxide doped with Pd and Pt (0.1; 0.2; 0.3 and 0.5%) with and without zeolite coating are presented in contact with 3% methanol and 12% ethanol. In these assays, the stability and reproducibility of the sensing signal at different working temperatures (200, 220, 240, 260 and 280⁰C) were analyzed.

The intensity of the response signal of the sensors in contact mainly with solutions of 3% methanol and 12% ethanol was determined. And it was found that the working temperature with which the highest intensity in the response signal was obtained was 260 ⁰C. At this temperature the sensors with the best results were: 0.1% Pd / SnO2; 0.1% Pd / SnO2-Z; 0.2% Pd / SnO2-Z; 0.1% Pt / SnO2; 0.2% Pt / SnO2; 0.1% Pt / SnO2-Z and 0.2% Pt / SnO2-Z.

In most of the cases studied, it was observed that the sensing signal was repetitive and stable, maintaining its amplitude and shape during the analysis. However, at the temperature of 280 ° C the signal loses intensity and becomes distorted.

The response signals of the zeolite-coated sensors presented greater intensity and stability compared to those obtained with the same sensors without zeolite coating and with the tin oxide sensors without doping.

For example, in detecting 12% ethanol, as the sensing temperature increases from 200 ° C to 260 ° C, the sensitivity of doped sensors increases with respect to SnO2 and this effect is greater in sensors with zeolite coating. This is possibly due to the semiconductor nature of tin oxide that becomes more sensitive as the temperature increases, its surface becomes richer in electrons due to the increase of the more reactive species (O-adsorbed), which reacts with the alcohols (reducing substances), producing a flow of electrons towards the surface of the oxide that increases the conductivity of the sensor. This effect is increased by incorporating small amounts of palladium or platinum and adding a layer of zeolite. The sensing signal is not very stable and the distortion is greater at a temperature of 280 ° C where, in addition, a decrease in the intensity of the sensor response is observed.
A Nonenzymatic Electrochemical Nitrite Sensor Based on Nickel Phosphide Electrodeposited on Ni Foam
Authors: Lu Shun , Hummel Matthew , Jia Hongxing , Gu Zhengrong
Published: July 2021

The detection of nitrite in drinking water and consumables is a critical process for preventing major threats to human health. While integral to normal body functions in low levels, large amounts of nitrite can result in poisoning in the short-term and the development of cancers over an extended period of time, due to nitrite’s interference with hemoglobin’s oxygen transport role in the blood by irreversible binding. Electroanalysis approach is regarded as a promising method to achieve excellent sensitivity and highly selectivity due to molecular redox on the surface of the working electrode. It has many benefits than spectrophotometry and high-performance liquid chromatography. It is note that, electrode modification is of importance for improving sensitivity and anti-interference performance in this process. However, conventional electrode modifications were mainly based on glassy carbon electrode or screen-print electrode. It is difficult to achieve the modified electrode’s maximum performance owing to the electrocatalyst is easily peeled off during electroanalysis. So, electrocatalyst grown on the electrode can fundamentally solve this problem without any conductive binder. In this abstract, a sensitive novel non-enzymatic nitrite electrochemical sensor based on nickel phosphide electrodeposited on Ni foam (NiP/NF) was described.

Results from our electrochemical investigations clearly demonstrate the excellent sensitivity and electrocatalytic activity of NiP/NF towards nitrite (Figure 1). The sensor has exhibited great electrochemical detection ability with a sensitivity of 1.56 × 10-4 mA μM-1, a linear range from 0.1 to 4000 μM and a detection limit of 0.01 μM (s/n = 3). These good performances can be attributed to the simple in-situ electrodeposition and great electrocatalytic performance of NiP. Moreover, good stability of the electrodeposited electrode can be ascribed to the in-situ growth route to construct a binder-free electrode. These results provide a new way to fabricate a novel electrochemical nitrite sensor. Further works will be carried out to investigate the properties of M-P, (M refers to Fe, Co, Mn, Cu, etc.) to detect nitrite.

Figure 1. Electrodeposition of NiP/NF and its electroanalysis toward nitrite. (a) Scheme of preparation of NiP/NF, (b) Electrodeposition process of NiP/NF, (c) SEM and mapping images of NiP/NF, and (d) Amperometric responses of nitrite on NiP/NF upon successive addition of nitrite to 0.1 M PBS (pH 7.0) under an applied potential of 0.8 V.

Figure 1
Development of a Portable Electrochemical Sensor for the Detection of Perfluoroalkyl Species
Authors: Rehman Abd Ur , Andreescu Emanuela
Published: July 2021

Per and poly-fluoroalkyl substances (PFAS) are emerging as harmful organic micropollutants and adversely affecting the environment. These compounds are a point of interest in recent years due to their bioaccumulation and toxic effects on humans, animals, and the aquatic environment. PFAS have strong carbon-fluorine bonds, which makes them resistant to degradation. Generally, PFAS quantification is done by conventional analytical techniques like LC-MS/MS, GC-MS, etc. Despite their high reliability and accuracy, these laboratory-based techniques are expensive and can analyze only a limited number of samples. There is a critical need to develop robust, cost-effective, and sensitive techniques for the onsite quantification of PFAS. This presentation will describe the new electrochemical method developed for the selective detection of PFOS under the guidelines of EPA. In this method, electropolymerized glassy carbon electrodes are used to study the interaction. The electrochemical sensor design and its characteristic binding interaction with specific PFAS will be discussed. This method can be used as a portable sensor for the onsite selective and sensitive quantification of PFAS.
Ultra-Low Detection Limit MEMS Hydrogen Sensor Based on SnO2 Nanospheres with Lots of Defects
Authors: Luo Na , Xu Jiaqiang
Published: July 2021

In this paper, SnO2 nanospheres with a lot of defects (SnO2-D) were synthesized simply by annealing SnO2 at the different temperature (300 °C, 400 °C and 500 °C) in the hydrogen (H2) atmosphere. There are many oxygen vacancies in SnO2 due to reaction between H2 and oxygen when the SnO2 was exposed in H2 atmosphere. The X-ray photoelectron spectroscopy (XPS) and Electron paramagnetic resonance (EPR) analysis showed that there are abundant oxygen vacancies on the surface of the SnO2-D4 (with the optimal annealing temperature of SnO2 is 400 °C). The gas sensitivity test results show that sensor based on SnO2-D4 showed an ultra-sensitive H2 detection ability down to 1 ppm. Moreover, the response of the sensor fabricated with SnO2-D4 to 10 ppm H2 at the optimal operating temperature of 250 °C is as high as 2.7, which is about 2 times higher than that of the SnO2 sensor. The improved gas sensing properties can be attributed to generation of oxygen vacancies in the SnO2-D4. Our present results demonstrate that SnO2 with abundant oxygen vacancies can significantly to detect the ultra-low concentration H2 and the method of manufacturing oxygen vacancies defects has great potential in improving the gas-sensing performance of metal oxide semiconductor.

Figure 1
Highly Sensitive and Selective H2S Gas Sensor Based on Co32 Cluster
Authors: Liu Yanan , Xu Jiaqiang , Bai Yueling
Published: July 2021

Hydrogen sulfide (H2S), as a typical colorless, flammable and poisonous gas having rotten eggs smell, can paralyze the nervous and respiratory system and even lead to death. Therefore, developing a fast and highly sensitive H2S gas sensor is urgently required. Metal clusters feature small size structures, large surface areas and polymetallic centers, demonstrating giant potential on catalysis applications. Moreover, the high-density absorption sites make it easier for clusters to interact with target molecules. Here, we reported a novel H2S gas sensor based on a polynuclear cobalt cluster compound {Co32}. At the optimal working temperature of 200 ℃, the sensor based on {Co32} exhibits an outstanding H2S selectivity against other interfering gases, such as carbon monoxide, methane, and ethanol. In addition, it is of great importance to design low detection limit H2S sensor with fast response and recovery time. Gas sensitivity test results show the presented {Co32} gas sensor exhibits fast response and recovery of 15 s and 34 s under 100 ppb H2S, respectively. Moreover, the sensor also has a good linearity property from 20 ppb to 1000 ppb, good reproducibility and stability with time and under different humidity conditions. Prominently, the distinctive sensing performance of cobalt cluster for H2S promotes the development of metal clusters in the field of gas sensing.

Figure 1
(Invited) Sensors for Agricultural Pests Management
Authors: Bhagat Deepa
Published: July 2021

Pests are undesired living organisms which cause major threat to plants, animals, humans and other organisms. It can directly feed on the crops and indirectly spread diseases and decrease the productivity of plants. Traditionally we have been using pesticides to get rid of them, but these pesticides are chemicals which tend to accumulate in the soil and water and pose detrimental effects to all the living creatures. To reduce the major loss in food production and use of chemical pesticides, we have come up with a few innovative approaches to control pests and also detect the toxic pesticides in an easy, affordable and eco-friendly way using sensors. We had developed sensors for effective use of biopesticides such as Helicoverpa armigera nuclear polyhedrosis virus (HaNPV), Spodoptera litura nuclear polyhedrosis virus (SlNPV) and Spilosoma obliqua nuclear polyhedrosis virus (SpilNPV). We had also designed a silicon dioxide-based microelectro-mechanical system (MEMS) sensors as tool for an early selective pest detection of female sex pheromones of Helicoverpa armigera and Bactrocera oleae. This robust device can also be used to selectively measure the pheromone at femtogram levels, and it is handy for early detection of pests. The device works well in both rainy and peak summer seasons. Using these systems farmers can take necessary measures in the pest attack region without using pesticides and would be able to support organic farming.
Strategies for Chemical Sensing Using High Purity Semiconducting Single-Walled Carbon Nanotube Electronic Devices
Authors: Lapointe Francois
Published: July 2021

Semiconducting single-walled carbon nanotubes (sc-SWCNTs) are attractive in chemical sensing [1] because of their peculiarities: As they present a single atom-thick wall and a quasi 1D form factor, sc-SWCNTs are especially sensitive to their surroundings' electrostatics. Moreover, their band gap of approximately 1 eV is much greater than room-temperature thermal energy while being in a convenient range for electronic applications. Also, their electronic structure exhibits van Hove singularities (sharp spikes in the density of states) that drastically alters their conductivity and optical properties when charge carriers are injected. Although sc-SWCNT electronic devices are very sensitive, they lack in selectivity and they usually need to be functionalized to implement a lock-and-key detection mechanism.

In this talk, we will present various strategies for chemical sensing using enriched sc-SWCNTs. We will discuss the advantages and disadvantages of using sc-SWCNTs in electronic chemical sensing devices. Sub-ppm ammonia sensing will be demonstrated using a sc-SWCNT material wrapped with a decomposable polymer in a chemiresistor configuration. [2] Also using chemiresistors, CO2 detection has been achieved by designing a SWCNT-wrapping polymer with specific interactions. [3] Finally, we will present a strategy to differentiate the response of sensor elements to a variety of volatile analytes by changing the polymer gate dielectrics in a three-terminal bottom gate chemitransistor configuration. [4] This methodology opens the way to the implementation of sc-SWCNT-based chemitransistors in a printed cross-reactive sensor array.

References

[1] Schroeder, V. et al. Carbon Nanotube Chemical Sensors. Chem. Rev.
119, 599–663 (2019)

[2] Li, Z. et al. Decomposable s-Tetrazine Copolymer Enables Single-Walled Carbon Nanotube Thin Film Transistors and Sensors with Improved Sensitivity. Adv. Funct. Mater. 1705568 (2018)

[3] Guo, C. et al. Enrichment of Semiconducting Single-Walled Carbon Nanotubes with Indigo-Fluorene-Based Copolymers and Their Use in Printed Thin-Film Transistors and Carbon Dioxide Gas Sensors. ACS Sensors
5 2136–2145 (2020)

[4] Lapointe, F. et al. Carbon Nanotube Transistors as Gas Sensors: Response Differentiation using Polymer Gate Dielectrics. ACS Appl. Polym. Mater.
1 3269-3278 (2019)
Perovskite-Based Gas Sensing Network for Environmental Condition Monitoring
Authors: Hossain Mohammad Shakhawat , Takshi Arash
Published: July 2021

Volatile Organic Compounds (VOCs) are one of the major concerns in terms of environmental pollution. In indoor environment, they can contribute to breathing difficulty, eye irritation, nausea, and can even cause damage to the central nervous system. Detecting the presence of these gases has become essential in environmental monitoring. The aim of this study is to investigate the sensitivity and selectivity of methylammonium lead iodide (MAPbI3) perovskites to an array of different VOC gases under illuminated condition. In our experiment, at first microchannels were created on indium tin oxide (ITO) coated plastic substrates. Then perovskite precursor solution was dropped on the microchannels, and leveraging the capillary motion force, the microchannels were filled eventually. After the crystallization of the solution, the perovskite was exposed to the VOCs and the current-voltage (I-V) characteristic responses of the perovskite before and after the exposure to the gases were studied. The photocurrent response to ethanol, methanol and acetone have been studied, and a variation among them has been observed. The sensor exhibited negligible changes in I-V response to ethanol and acetone, however, upon exposure to methanol, at 2.0 V voltage bias, the photocurrent decreased by about 25%. Our initial study also indicates that the photocurrent response is significantly affected under illuminated condition and one of the major concerns of this study is to investigate how lights of different wavelengths can influence the responsivity of the device. The experimental data for sensing VOCs at room temperature shows great promise for the development of an array of gases sensing devices that can be integrated into an “electronic nose” for detecting the presence of harmful gases in the environment.
Implementation of Bounded Diffusion Impedance in a Model Pyeis to Correctly Simulate Flow Gradient on Channel-Electrode in Microfluidics
Authors: Boukraa Rassen , Poujouly Claire , Gonzalez-Losada Pedro , Gamby Jean
Published: July 2021

Here, we proposed to test the limits of the bounded diffusion impedance model by using electrochemical impedance spectroscopy (EIS) measurements in a microfluidic device architecture bearing a set of microelectrodes integrated in microchannel. This EIS Nyquist plot behaviour was currently modelled with the Randles equivalent circuit. In this work, one of the main advantages for using PyEIS (a Python-based Electrochemical Impedance Spectroscopy) software is being able to modify and correct the models with a simple implementation in the source code freely accessible on the website of the author Kristian B. Knudsen. The obtained results after implementing the diffusion-convective equation in the PyEIS code permits to adapt each function to be able to plot, simulate and fit a specific modified Randles for channel-electrode. The modified Randles was used for preliminary tests for optimization of the parameters of flow in the microfluidic channel by comparing the diffusion layer thickness as a function with the volumetric flow.
(Invited) Considerations in the Scale-up of Lab-on-Chip and Microfluidics Products
Authors: Levine Leanna
Published: July 2021

Microfluidics-based products are particularly difficult to transition efficiently from a laboratory concept to a beta product that meets target costs for a consumable. The reasons for this has to do with the complexity of microfluidics products, including the use of multiple manufacturing methods to create complete devices, the integration of reagents and liquids, and the integration of sensors. The presentation will discuss how to organize and navigate the product development process to achieve success.
Investigating Electrochemiluminescence at Surface Modified Boron Doped Diamond Electrodes
Authors: Stewart Samuel , Scorsone Emmanuel , Hamel Matthieu
Published: July 2021

Electrochemiluminescence (ECL) is an analytical technique where chemical species generated at the surface of an electrode interact; producing an excited state, which then emits photons. The intensity of the emitted light is proportional to the concentration of the target molecule and so is quantifiable. Exploiting features of both electrochemical analysis and chemiluminescence, the use of ECL has become very popular in many fields due to the wide range of advantages it displays over other fluorescence techniques. This includes: the ability to control the exact time and position of the photon emission, the absence of background optical signal and high selectivity. ECL can be performed in organic solvents, to great effect, where the oxidized and reduced forms of the target analyte can readily be produced by sweeping from cathodic to anodic potential, or vice versa. The recombination of these two species is what produces the excited state, then resulting in a detectable ECL signal. The ability to product both of these two species becomes more difficult when moving to aqueous solutions as the relatively high and low potentials needed can cause the electrolysis of water, thus disrupting the ECL process. This is often overcome with the use of a co-reacting species, where the luminescent species are oxidized at the electrode together with the co-reactant, giving a strong reducing agent. To this effect, Boron Doped Diamond electrodes have several advantages over more conventional electrodes, including high electrochemical stability, resilience to fouling, and good optical transparency. Most importantly for ECL assays is that it possesses a wide potential window in water, meaning we have the ability to mitigate the splitting of water without the need of adding extra co-reactants to the solution. Furthermore, BDD can easily undergo many different surface modifications. Here, the analytical ECL potential of diamond will be demonstrated through comparative studies using different electrode materials. This will including the use of diamond grown on non-planer substrates – creating highly porous electrodes, the addition of sputtered transition metal nanoparticles on the surface of the electrode and changes to the surface termination of the BDD to alter its hydrophobicity.
Development of New Chemiluminescence Systems for Analysis
Authors: Xu Guoobao , Gao Wenyue , Saqib Muhammad
Published: July 2021

Chemiluminescence (CL) is a light-emitting phenomenon as a result of chemical reactions. Luminol and lucigenin are typical CL luminophores, and hydrogen peroxide is typical coreactant. It is an important analytical technique because of its inherent features, such as high sensitivity, wide dynamic range, fast detection, simple equipment, and low instrumentation costs because no external light source or optics is needed. It has been extensively used for immunoassays, DNA detection, enzymatic biosensors, forensic bloodstain detection, pharmaceutical analysis, metal ion determination, imaging and so on. To improve performance of CL analysis and broaden the applications of CL, it is of great importance to develop new CL systems.

Herein, we present some new CL systems such as artemisinin/luminol, thiourea dioxide/luminol, N-hydroxyphthalimide/luminol, hydroxylamine-O-sulfonic acid/luminol, allantoin/ lucigenin and creatinine/H2O2 systems. We will also demonstrate their applications in forensic bloodstain detection, enzyme detection, metal ions detection, and so on [1-3].

Acknowledgment

We are grateful for financial support from the National Key Research and Development Program of China (No. 2016YFA0201300), National Natural Science Foundation of China (Nos. 21874126,21675148), the Chinese Academy of Sciences (CAS)-the Academy of Sciences for the Developing World (TWAS), President’s Fellowship Program, and the CAS President's International Fellowship Initiative (PIFI) project.

References

(1) Wenyue Gao, Chao Wang, Kateryna Muzyka, Shimeles Addisu Kitte, Jianping Li, Wei Zhang and Guobao Xu*. Artemisinin-luminol chemiluminescence for forensic bloodstain detection using smart phone as detector. Anal. Chem., 2017, 89 (11), 6160–6165.

(2) Wenyue Gao, Wenjing Qi, Jianping Lai, Liming Qi, Saadat Majeed and Guobao Xu*. Thiourea dioxide as unique eco-friendly coreactant of luminol chemiluminescence for sensitive detection of luminol, thiourea dioxide, and cobalt ions. Chem. Commun., 2015, 51(9), 1620–1623.

(3) Muhammad Saqib, Liming Qi, Pan Hui, Anaclet Nsabimana, Mohamed Ibrahim Halawa, Wei Zhang,* Guobao Xu*. Development of luminol-N-hydroxyphthalimide chemiluminescence system for highly selective and sensitive detection of superoxide dismutase, uric acid and Co2+. Biosens. Bioelectron., 2018, 99, 519-524.
Near Infrared Fluorescent Nanomaterials for Biosensing Applications
Authors: Mann Florian , Selvaggio Gabriele , Nissler Robert , Kruss Sebastian
Published: July 2021

Nanomaterials have novel properties due to quantum confinement and high surface areas and are therefore interesting for both fundamental studies and applications. One important property of many nanomaterials is fluorescence, which provides insights into electronic structure and local chemical processes. Additionally, fluorescence is a valuable tool to detect biomolecules. We are interested in 1D and 2D near infrared (NIR) fluorescent materials because this region of the spectrum (800 nm -1700 nm) promises ultra-low background and scattering. One example are semiconducting single-walled carbon nanotubes (SWCNTs). We developed different non-covalent concepts and quantum defects to tailor the organic phase around SWCNTs and tune both molecular interactions and photophysics. It allowed us to understand mechanistically how conformational changes of the organic phase affects the NIR fluorescence spectra of the SWCNTs. These functionalized SWCNTs can be used to detect and label (bio)molecules over multiple length scales: Single proteins, release of signaling molecules such as neurotransmitters from cells and stress (reactive oxygen species) in plants. Another example are 2D NIR fluorescent silicate nanosheets that have size-dependent fluorescence lifetimes in the µs range and enable lifetime-encoded fluorescence microscopy and detection methods.

In summary, we present fundamental insights into the engineering of NIR fluorescent materials and their interfaces and the potential for biosensing.
Visualization and Evaluation of the Masking of Malodor-Evoked Activity By Fragrance in Mammalian Olfactory Epithelium Using Biohybrid Nose
Authors: Zhuang Liujing , Wei Xinwei , Jiang Nan , Yuan Qunchen , Qin Chunlian , Jiang Deming , Liu Mengxue , Wang Ping
Published: July 2021

Olfaction is a synthetic sense. The most common result of mixing two odors is masking one component by another. However, there is lack of analytical techniques for measuring the sense of smell. Here, we propose a biohybrid nose for objective and quantitative evaluation of malodor masking efficiency of perfumed products. This biohybrid nose is constructed by integrating mammalian olfactory epithelium with microelectrode array to read out the olfactory information as electrical signal. The intrinsic odor response of olfactory epithelium is found to be represented by widespread spatiotemporal oscillatory activity. The masking efficiency of fragrance is quantified by calculating the relative difference between the malodor and the binary mixture response patterns. Results indicate that masking efficiency of fragrance is concentration-dependent, whereas completely masking may occurs when fragrance is employed at a concentration 2-3 orders of magnitude higher than malodor. This study demonstrates for the first time that biohybrid system provides an effective technique to resolve more complex biosensing-related issues such as odor interactions in mixtures.

Figure 1
Calcium-Ion Materials: A Next Generation MV Energy Storage System
Authors: Vaughey John T. , Kim Sanghyeon , Park Haesun , Yin Liang , Parajuli Prakash , Fister Tim , Lapidus Saul , Zapol Peter , Klie Robert F.
Published: July 2021

Next-generation energy storage materials are an important step towards creating new chemistries and identifying new phenomena that can alter the energy storage landscape. While lithium-ion systems have been with us for nearly 50 years since the groundbreaking work of Whittingham on titanium disulfide, systems based on alternatives to lithium have been far less studied. While the performance metrics of lithium-ion systems has been well recognized, systems based on sodium, magnesium, or calcium are still in their infancy with only hints of their potential. For instance, sodium-ion systems haver the advantage that sodium does not react with aluminum at room temperature and thus significant costs savings can be seen for the anode-side current collector foils. Various researchers have shown that Mg+2 has high mobility in spinel frameworks and that its rate capability may be similar to lithium ion systems. In this presentation, we will highlight recent advances in calcium-ion chemistry and relate the observed performance to the underlying properties of the various host frameworks. Issues connecting the electrochemical properties to system level issues and other cell components will be addressed.

Figure 1