Pub Date : 2022-01-14DOI: 10.3389/fsens.2021.796789
Mengya Sun, B. Shi, Junyi Guo, Hong-hu Zhu, Hongtao Jiang, Jie Liu, G. Wei, Xing Zheng
Accurate acquisition of the moisture field distribution in in situ soil is of great significance to prevent geological disasters and protect the soil ecological environment. In recent years, rapidly developed fiber-optic sensing technology has shown outstanding advantages, such as distributed measurement, long-distance monitoring, and good durability, which provides a new technical means for soil moisture field monitoring. After several years of technical research, the authors’ group has made a number of new achievements in the development of fiber-optic sensing technology for the soil moisture field, that is, two new fiber-optic sensing technologies for soil moisture content, including the actively heated fiber Bragg grating (AH-FBG) technology and the actively heated distributed temperature sensing (AH-DTS) technology, and a new fiber-optic sensing technology for soil pore gas humidity are developed. This paper systematically summarizes the three fiber-optic sensing technologies for soil moisture field, including sensing principle, sensor development and calibration test. Moreover, the practical application cases of three fiber-optic sensing technologies are introduced. Finally, the development trend of fiber-optic sensing technology for soil moisture field in the future is summarized and prospected.
{"title":"Development and Application of Fiber-Optic Sensing Technology for Monitoring Soil Moisture Field","authors":"Mengya Sun, B. Shi, Junyi Guo, Hong-hu Zhu, Hongtao Jiang, Jie Liu, G. Wei, Xing Zheng","doi":"10.3389/fsens.2021.796789","DOIUrl":"https://doi.org/10.3389/fsens.2021.796789","url":null,"abstract":"Accurate acquisition of the moisture field distribution in in situ soil is of great significance to prevent geological disasters and protect the soil ecological environment. In recent years, rapidly developed fiber-optic sensing technology has shown outstanding advantages, such as distributed measurement, long-distance monitoring, and good durability, which provides a new technical means for soil moisture field monitoring. After several years of technical research, the authors’ group has made a number of new achievements in the development of fiber-optic sensing technology for the soil moisture field, that is, two new fiber-optic sensing technologies for soil moisture content, including the actively heated fiber Bragg grating (AH-FBG) technology and the actively heated distributed temperature sensing (AH-DTS) technology, and a new fiber-optic sensing technology for soil pore gas humidity are developed. This paper systematically summarizes the three fiber-optic sensing technologies for soil moisture field, including sensing principle, sensor development and calibration test. Moreover, the practical application cases of three fiber-optic sensing technologies are introduced. Finally, the development trend of fiber-optic sensing technology for soil moisture field in the future is summarized and prospected.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43081111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-11DOI: 10.3389/fsens.2021.751748
F. Gebali, M. Mamun
Physically unclonable functions (PUFs) are now an essential component for strengthening the security of Internet of Things (IoT) edge devices. These devices are an important component in many infrastructure systems such as telehealth, commerce, industry, etc. Traditionally these devices are the weakest link in the security of the system since they have limited storage, processing, and energy resources. Furthermore they are located in unsecured environments and could easily be the target of tampering and various types of attacks. We review in this work the structure of most salient types of PUF systems such as static RAM static random access memory (SRAM), ring oscillator (RO), arbiter PUFs, coating PUFs and dynamic RAM dynamic random access memory (DRAM). We discuss statistical models for the five most common types of PUFs and identify the main parameters defining their performance. We review some of the most recent algorithms that can be used to provide stable authentication and secret key generation without having to use helper data or secure sketch algorithms. Finally we provide results showing the performance of these devices and how they depend on the authentication algorithm used and the main system parameters.
{"title":"Review of Physically Unclonable Functions (PUFs): Structures, Models, and Algorithms","authors":"F. Gebali, M. Mamun","doi":"10.3389/fsens.2021.751748","DOIUrl":"https://doi.org/10.3389/fsens.2021.751748","url":null,"abstract":"Physically unclonable functions (PUFs) are now an essential component for strengthening the security of Internet of Things (IoT) edge devices. These devices are an important component in many infrastructure systems such as telehealth, commerce, industry, etc. Traditionally these devices are the weakest link in the security of the system since they have limited storage, processing, and energy resources. Furthermore they are located in unsecured environments and could easily be the target of tampering and various types of attacks. We review in this work the structure of most salient types of PUF systems such as static RAM static random access memory (SRAM), ring oscillator (RO), arbiter PUFs, coating PUFs and dynamic RAM dynamic random access memory (DRAM). We discuss statistical models for the five most common types of PUFs and identify the main parameters defining their performance. We review some of the most recent algorithms that can be used to provide stable authentication and secret key generation without having to use helper data or secure sketch algorithms. Finally we provide results showing the performance of these devices and how they depend on the authentication algorithm used and the main system parameters.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44785159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-06DOI: 10.3389/fsens.2021.815209
Yanyan Fan, Hongbin Zhao, Yifan Yang, Yi Yang, Tianling Ren, H. Tu
Graphene-based stretchable and flexible strain sensors are one of the promising “bridges” to the biomedical realm. However, enhancing graphene-based wearable strain sensors to meet the demand of high sensitivity, broad sensing range, and recoverable structure deformation simultaneously is still a great challenge. In this work, through structural design, we fabricated a simple Ecoflex/Overlapping Graphene/Ecoflex (EOGE) strain sensor by encapsulating a graphene sensing element on polymer Ecoflex substrates using a drop-casting method. The EOGE strain sensor can detect stretching with high sensitivity, a maximum gauge factor of 715 with a wide strain range up to 57%, and adequate reliability and stability over 1,000 cycles for stretching. Moreover, the EOGE strain sensor shows recoverable structure deformation, and the sensor has a steady response in the frequency disturbance test. The good property of the strain sensor is attributed to the resistance variation induced by the overlap and crack structure of graphene by structural design. The vibrations caused by sound and various body movements have been thoroughly detected, which exhibited that the EOGE strain sensor is a promising candidate for wearable biomedical electronic applications.
{"title":"A Practical Strain Sensor Based on Ecoflex/Overlapping Graphene/Ecoflex Sandwich Structures for Vocal Fold Vibration and Body Motion Monitoring","authors":"Yanyan Fan, Hongbin Zhao, Yifan Yang, Yi Yang, Tianling Ren, H. Tu","doi":"10.3389/fsens.2021.815209","DOIUrl":"https://doi.org/10.3389/fsens.2021.815209","url":null,"abstract":"Graphene-based stretchable and flexible strain sensors are one of the promising “bridges” to the biomedical realm. However, enhancing graphene-based wearable strain sensors to meet the demand of high sensitivity, broad sensing range, and recoverable structure deformation simultaneously is still a great challenge. In this work, through structural design, we fabricated a simple Ecoflex/Overlapping Graphene/Ecoflex (EOGE) strain sensor by encapsulating a graphene sensing element on polymer Ecoflex substrates using a drop-casting method. The EOGE strain sensor can detect stretching with high sensitivity, a maximum gauge factor of 715 with a wide strain range up to 57%, and adequate reliability and stability over 1,000 cycles for stretching. Moreover, the EOGE strain sensor shows recoverable structure deformation, and the sensor has a steady response in the frequency disturbance test. The good property of the strain sensor is attributed to the resistance variation induced by the overlap and crack structure of graphene by structural design. The vibrations caused by sound and various body movements have been thoroughly detected, which exhibited that the EOGE strain sensor is a promising candidate for wearable biomedical electronic applications.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43695695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-05DOI: 10.3389/fsens.2021.804556
M. Fernández-Ruiz, M. Soriano-Amat, H. Martins, V. Durán, S. Martín-López, M. González-Herráez
We have demonstrated a novel scheme for distributed optical fiber sensing based on the use of a dual frequency comb, which enables the development of a high-resolution (in the cm range) distributed sensor with significantly relaxed electronic requirements compared with previous schemes. This approach offers a promising solution for real time structure monitoring in a variety of fields, including transportation, manufacturing or mechatronics. In this work, we review the principle of operation of the technique, recent advances to improve its performance and different experimental tests.
{"title":"High Resolution Distributed Optical Fiber Sensing Using Time-Expanded Phase-Sensitive Reflectometry","authors":"M. Fernández-Ruiz, M. Soriano-Amat, H. Martins, V. Durán, S. Martín-López, M. González-Herráez","doi":"10.3389/fsens.2021.804556","DOIUrl":"https://doi.org/10.3389/fsens.2021.804556","url":null,"abstract":"We have demonstrated a novel scheme for distributed optical fiber sensing based on the use of a dual frequency comb, which enables the development of a high-resolution (in the cm range) distributed sensor with significantly relaxed electronic requirements compared with previous schemes. This approach offers a promising solution for real time structure monitoring in a variety of fields, including transportation, manufacturing or mechatronics. In this work, we review the principle of operation of the technique, recent advances to improve its performance and different experimental tests.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46705420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the novel coronavirus responsible for COVID-19. Infection in humans requires angiotensin-converting enzyme II (hACE2) as the point of entry for SARS-CoV-2. PCR testing is generally definitive but expensive, although it is highly sensitive and accurate. Biosensor-based monitoring could be a low-cost, accurate, and non-invasive approach to improve testing capacity. We develop a capacitive hACE2 biosensor for intact SARS-CoV-2 detection in saliva. Laser-induced graphene (LIG) electrodes were modified with platinum nanoparticles. The quality control of LIG electrodes was performed using cyclic voltammetry. Truncated hACE2 was used as a biorecognition element and attached to the electrode surface by streptavidin-biotin coupling. Biolayer interferometry was used for qualitative interaction screening of hACE2 with UV-attenuated virions. Electrochemical impedance spectroscopy (EIS) was used for signal transduction. Truncated hACE2 binds wild-type SARS-CoV-2 and its variants with greater avidity than human coronavirus (common cold virus). The limit of detection (LoD) is estimated to be 2,960 copies/ml. The detection process usually takes less than 30 min. The strength of these features makes the hACE2 biosensor a potentially low-cost approach for screening SARS-CoV-2 in non-clinical settings with high demand for rapid testing (for example, schools and airports).
{"title":"Development of a Biosensor Based on Angiotensin-Converting Enzyme II for Severe Acute Respiratory Syndrome Coronavirus 2 Detection in Human Saliva.","authors":"Geisianny Moreira, Lisseth Casso-Hartmann, Shoumen Palit Austin Datta, Delphine Dean, Eric McLamore, Diana Vanegas","doi":"10.3389/fsens.2022.917380","DOIUrl":"10.3389/fsens.2022.917380","url":null,"abstract":"<p><p>Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the novel coronavirus responsible for COVID-19. Infection in humans requires angiotensin-converting enzyme II (hACE2) as the point of entry for SARS-CoV-2. PCR testing is generally definitive but expensive, although it is highly sensitive and accurate. Biosensor-based monitoring could be a low-cost, accurate, and non-invasive approach to improve testing capacity. We develop a capacitive hACE2 biosensor for intact SARS-CoV-2 detection in saliva. Laser-induced graphene (LIG) electrodes were modified with platinum nanoparticles. The quality control of LIG electrodes was performed using cyclic voltammetry. Truncated hACE2 was used as a biorecognition element and attached to the electrode surface by streptavidin-biotin coupling. Biolayer interferometry was used for qualitative interaction screening of hACE2 with UV-attenuated virions. Electrochemical impedance spectroscopy (EIS) was used for signal transduction. Truncated hACE2 binds wild-type SARS-CoV-2 and its variants with greater avidity than human coronavirus (common cold virus). The limit of detection (LoD) is estimated to be 2,960 copies/ml. The detection process usually takes less than 30 min. The strength of these features makes the hACE2 biosensor a potentially low-cost approach for screening SARS-CoV-2 in non-clinical settings with high demand for rapid testing (for example, schools and airports).</p>","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":"3 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9386735/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40715445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-17DOI: 10.3389/fsens.2021.813445
D. Puglisi
Sensors for air quality monitoring have quickly gained popularity due to increased concerns related to air pollution and spread of air contaminants both indoors and outdoors. The protracted experiences of lockdowns, self-quarantines, use of facemasks during the coronavirus pandemic (COVID-19) put the air quality issue in the spotlight worldwide, and have made people more environmentally and health aware. The increasing availability and applicability of sensors for air quality monitoring offers the possibility to design and prototype customized low-cost sensor systems (LCSS) and multisensor platforms easier than ever before, not only for research or industrial purposes, but also for personal exposure assessment, complementary network measurements, educational training, and student projects (Lenartz et al.; Höfner et al.). Sensor-based intelligent systems have entered our daily life and found an increased use in health, environmental, and safety-related applications, thanks to the remarkable improvements on sensing materials and device performance. Significant efforts have been done to achieve increased sensitivity, selectivity, long-term stability, reproducibility, as well as decreased response time and operation temperature (Saruhan et al.; Domènch-Gil et al.). Moreover, proper calibration, rigorous data analysis, evaluation and validation methods are key factors of substantial improvement of sensor performance and enhanced reliability of concentration readings (Lenartz et al.). Advances in materials research have played a crucial role for decades for the development of highperformance gas sensors. Metal oxide (MOx) semiconductor materials have been widely used since the 1950s to fabricate chemoresistive gas sensors due to their excellent sensing properties such as high sensitivity and long-term stability, possibility to control their properties by synthesis methods, ease of manufacture, cost effectiveness, and large-scale production potential compared to other types of gas sensors (Saruhan et al.; Domènch-Gil et al.). Among all, particular focus has been given to nanostructured SnO2 and TiO2 as outstandingMOx sensing materials. The review article by Saruhan et al. reports the most important achievements related to SnO2 and TiO2 over the past 2 decades. The effects of physical and chemical material characteristics, such as crystal structure, morphology, size, surface modification, bulk doping on the gas sensor properties are also described. It has been proven that MOx are suitable for detecting a large variety of gases and that the sensing properties can be tuned by, e.g., bulk-doping, heterojunctions or surface functionalization. However, MOx-based sensors usually suffer from poor selectivity due to their high sensitivity to several gas species, which is an issue that needs further research to be overcome. An important factor to consider when fabricating micro or nanostructured MOx-based chemoresistive gas sensors is the amount and distribution
{"title":"Editorial: Sensors for Air Quality Monitoring, Indoor and Outdoor","authors":"D. Puglisi","doi":"10.3389/fsens.2021.813445","DOIUrl":"https://doi.org/10.3389/fsens.2021.813445","url":null,"abstract":"Sensors for air quality monitoring have quickly gained popularity due to increased concerns related to air pollution and spread of air contaminants both indoors and outdoors. The protracted experiences of lockdowns, self-quarantines, use of facemasks during the coronavirus pandemic (COVID-19) put the air quality issue in the spotlight worldwide, and have made people more environmentally and health aware. The increasing availability and applicability of sensors for air quality monitoring offers the possibility to design and prototype customized low-cost sensor systems (LCSS) and multisensor platforms easier than ever before, not only for research or industrial purposes, but also for personal exposure assessment, complementary network measurements, educational training, and student projects (Lenartz et al.; Höfner et al.). Sensor-based intelligent systems have entered our daily life and found an increased use in health, environmental, and safety-related applications, thanks to the remarkable improvements on sensing materials and device performance. Significant efforts have been done to achieve increased sensitivity, selectivity, long-term stability, reproducibility, as well as decreased response time and operation temperature (Saruhan et al.; Domènch-Gil et al.). Moreover, proper calibration, rigorous data analysis, evaluation and validation methods are key factors of substantial improvement of sensor performance and enhanced reliability of concentration readings (Lenartz et al.). Advances in materials research have played a crucial role for decades for the development of highperformance gas sensors. Metal oxide (MOx) semiconductor materials have been widely used since the 1950s to fabricate chemoresistive gas sensors due to their excellent sensing properties such as high sensitivity and long-term stability, possibility to control their properties by synthesis methods, ease of manufacture, cost effectiveness, and large-scale production potential compared to other types of gas sensors (Saruhan et al.; Domènch-Gil et al.). Among all, particular focus has been given to nanostructured SnO2 and TiO2 as outstandingMOx sensing materials. The review article by Saruhan et al. reports the most important achievements related to SnO2 and TiO2 over the past 2 decades. The effects of physical and chemical material characteristics, such as crystal structure, morphology, size, surface modification, bulk doping on the gas sensor properties are also described. It has been proven that MOx are suitable for detecting a large variety of gases and that the sensing properties can be tuned by, e.g., bulk-doping, heterojunctions or surface functionalization. However, MOx-based sensors usually suffer from poor selectivity due to their high sensitivity to several gas species, which is an issue that needs further research to be overcome. An important factor to consider when fabricating micro or nanostructured MOx-based chemoresistive gas sensors is the amount and distribution ","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41370744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-07DOI: 10.3389/fsens.2021.826403
V. Johny, K. Chinmaya, Muhammed Nihal C. V., V. Kurian, G. M. Rao, M. Ghosh, Siddhartha Ghosh
A significantly large scope is available for the scientific and engineering developments of high-throughput ultra-high sensitive oxygen sensors. We give a perspective of oxygen sensing for two physical states of matters—solid-state nanomaterials and plasma. From single-molecule experiments to material selection, we reviewed various aspects of sensing, such as capacitance, photophysics, electron mobility, response time, and a yearly progress. Towards miniaturization, we have highlighted the benefit of lab-on-chip-based devices and showed exemplary measurements of fast real-time oxygen sensing. From the physical–chemistry perspective, plasma holds a strong potential in the application of oxygen sensing. We investigated the current state-of-the-art of electron density, temperature, and design issues of plasma systems. We also show numerical aspects of a low-cost approach towards developing plasma-based oxygen sensor from household candle flame. In this perspective, we give an opinion about a diverse range of scientific insight together, identify the short comings, and open the path for new physical–chemistry device developments of oxygen sensor along with providing a guideline for innovators in oxygen sensing.
{"title":"Towards Real-Time Oxygen Sensing: From Nanomaterials to Plasma","authors":"V. Johny, K. Chinmaya, Muhammed Nihal C. V., V. Kurian, G. M. Rao, M. Ghosh, Siddhartha Ghosh","doi":"10.3389/fsens.2021.826403","DOIUrl":"https://doi.org/10.3389/fsens.2021.826403","url":null,"abstract":"A significantly large scope is available for the scientific and engineering developments of high-throughput ultra-high sensitive oxygen sensors. We give a perspective of oxygen sensing for two physical states of matters—solid-state nanomaterials and plasma. From single-molecule experiments to material selection, we reviewed various aspects of sensing, such as capacitance, photophysics, electron mobility, response time, and a yearly progress. Towards miniaturization, we have highlighted the benefit of lab-on-chip-based devices and showed exemplary measurements of fast real-time oxygen sensing. From the physical–chemistry perspective, plasma holds a strong potential in the application of oxygen sensing. We investigated the current state-of-the-art of electron density, temperature, and design issues of plasma systems. We also show numerical aspects of a low-cost approach towards developing plasma-based oxygen sensor from household candle flame. In this perspective, we give an opinion about a diverse range of scientific insight together, identify the short comings, and open the path for new physical–chemistry device developments of oxygen sensor along with providing a guideline for innovators in oxygen sensing.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47127201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.3389/fsens.2021.725427
Takumi Kishi, T. Fujie, H. Ohta, S. Takeoka
Neurotransmitters, which are responsible for the signal transduction of nerve cells in the brain, are linked not only to various emotions and behaviors in our daily life, but also to brain diseases. Measuring neurotransmitters in the brain therefore makes a significant contribution to the progress of brain science. The purpose of this study is to develop a flexible thin film-type sensor that can electrochemically measure dopamine (DA) selectively and with high sensitivity. The thin-film sensor was prepared by printing gold colloidal ink on a polyimide film with a thickness of 25 µm—which the most flexible of the films examined that could maintain the buckling load (1 mN) required for insertion into the brain. The electrode (DA-PPy electrode) was then prepared by electropolymerization of polypyrrole (PPy) using DA as a template. The flexural rigidity of the sensor was 4.3 × 103 nNm, which is the lowest of any neurotransmitter sensors reported to date. When a DA solution (0–50 nM) was measured with the DA-PPy electrode using square-wave voltammetry (SWV), the slope of the calibration curve was 3.3 times higher than that of the PPy only negative control electrode, indicating an improvement in sensitivity by molecular imprinting with DA. The sensor was used to measure 0−50 nM norepinephrine (NE) and serotonin (5-HT), and the slope of the DA calibration curve at 0.24 V (19 ± 4.4 nA/nM) was much greater than those of NE (0.99 ± 3.3 nA/nM) and 5-HT (2.5 ± 2.4 nA/nM) because the selectivity for DA was also improved by molecular imprinting.
{"title":"Flexible Film-Type Sensor for Electrochemical Measurement of Dopamine Using a Molecular Imprinting Method","authors":"Takumi Kishi, T. Fujie, H. Ohta, S. Takeoka","doi":"10.3389/fsens.2021.725427","DOIUrl":"https://doi.org/10.3389/fsens.2021.725427","url":null,"abstract":"Neurotransmitters, which are responsible for the signal transduction of nerve cells in the brain, are linked not only to various emotions and behaviors in our daily life, but also to brain diseases. Measuring neurotransmitters in the brain therefore makes a significant contribution to the progress of brain science. The purpose of this study is to develop a flexible thin film-type sensor that can electrochemically measure dopamine (DA) selectively and with high sensitivity. The thin-film sensor was prepared by printing gold colloidal ink on a polyimide film with a thickness of 25 µm—which the most flexible of the films examined that could maintain the buckling load (1 mN) required for insertion into the brain. The electrode (DA-PPy electrode) was then prepared by electropolymerization of polypyrrole (PPy) using DA as a template. The flexural rigidity of the sensor was 4.3 × 103 nNm, which is the lowest of any neurotransmitter sensors reported to date. When a DA solution (0–50 nM) was measured with the DA-PPy electrode using square-wave voltammetry (SWV), the slope of the calibration curve was 3.3 times higher than that of the PPy only negative control electrode, indicating an improvement in sensitivity by molecular imprinting with DA. The sensor was used to measure 0−50 nM norepinephrine (NE) and serotonin (5-HT), and the slope of the DA calibration curve at 0.24 V (19 ± 4.4 nA/nM) was much greater than those of NE (0.99 ± 3.3 nA/nM) and 5-HT (2.5 ± 2.4 nA/nM) because the selectivity for DA was also improved by molecular imprinting.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43542742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-28DOI: 10.3389/fsens.2021.752600
Beatriz Oliveira, B. Veigas, P. Baptista
Nucleic acid amplification technologies (NAATs) have become fundamental tools in molecular diagnostics, due to their ability to detect small amounts of target molecules. Since its development, Polymerase Chain Reaction (PCR) has been the most exploited method, being stablished as the “gold standard” technique for DNA amplification. However, the requirement for different working temperatures leads to the need of a thermocycler machine or complex thermal apparatus, which have been preventing its application in novel integrated devices for single workflow and high throughput analysis. Conversely, isothermal amplification methods have been gaining attention, especially for point-of-care diagnosis and applications. These non-PCR based methods have been developed by mimicking the in vivo amplification mechanisms, while performing the amplification with high sensitivity, selectivity and allowing for high-throughput analysis. These favorable capabilities have pushed forward the implementation and commercialization of several platforms that exploit isothermal amplification methods, mostly against virus, bacteria and other pathogens in water, food, environmental and clinical samples. Nevertheless, the future of isothermal amplification methods is still dependent on achieving technical maturity and broader commercialization of enzymes and reagents.
{"title":"Isothermal Amplification of Nucleic Acids: The Race for the Next “Gold Standard”","authors":"Beatriz Oliveira, B. Veigas, P. Baptista","doi":"10.3389/fsens.2021.752600","DOIUrl":"https://doi.org/10.3389/fsens.2021.752600","url":null,"abstract":"Nucleic acid amplification technologies (NAATs) have become fundamental tools in molecular diagnostics, due to their ability to detect small amounts of target molecules. Since its development, Polymerase Chain Reaction (PCR) has been the most exploited method, being stablished as the “gold standard” technique for DNA amplification. However, the requirement for different working temperatures leads to the need of a thermocycler machine or complex thermal apparatus, which have been preventing its application in novel integrated devices for single workflow and high throughput analysis. Conversely, isothermal amplification methods have been gaining attention, especially for point-of-care diagnosis and applications. These non-PCR based methods have been developed by mimicking the in vivo amplification mechanisms, while performing the amplification with high sensitivity, selectivity and allowing for high-throughput analysis. These favorable capabilities have pushed forward the implementation and commercialization of several platforms that exploit isothermal amplification methods, mostly against virus, bacteria and other pathogens in water, food, environmental and clinical samples. Nevertheless, the future of isothermal amplification methods is still dependent on achieving technical maturity and broader commercialization of enzymes and reagents.","PeriodicalId":93754,"journal":{"name":"Frontiers in sensors","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49188079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-17DOI: 10.3389/fsens.2021.752754
O. Oliveira, Maria Cristina F. Oliveira
In this paper we discuss how nanotech-based sensors and biosensors are providing the data for autonomous machines and intelligent systems, using two metaphors to exemplify the convergence between nanotechnology and artificial intelligence (AI). These are related to sensors to mimic the five human senses, and integration of data from varied sources and natures into an intelligent system to manage autonomous services, as in a train station.
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