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Huang SJ, Li C, Feng JH, Selvaraju S, Subramani M. Mechanical and Corrosion Tests for Magnesium-Zinc/Ti-6Al-4V Composites by Gravity Casting. Materials (Basel) 2024; 17:1836. [PMID: 38673196 PMCID: PMC11050820 DOI: 10.3390/ma17081836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 04/28/2024]
Abstract
A new Mg-4Zn X Ti-6Al-4V (TC4, of 0, 1, and 3 wt.%) alloy was successfully fabricated by a simple and low-cost gravity casting method and heat treatment at 150 °C for 24 h. The composite was examined by XRD, uniaxial tests, FESEM/EDS, potentiostat/EIS, and immersion tests for the material's microstructures, mechanical properties, electrochemical characteristics, and corrosion resistance. Experimental results indicate that heat treatment enables the precipitation of Zn along the Mg grain boundaries and drives the co-precipitation of Al around the TC4 particles and nearby grain boundaries. Uniaxial tensile tests reveal that TC4 reinforces the Mg-Zn matrix material with higher elastic modulus, ultimate tensile stress, and toughness. The heat treatment further enhanced these mechanical properties. Electrochemical tests show that 1 wt.% TC4 composite exhibits the highest open circuit potential among all tested samples, which implies the 1 wt.% TC4-added Mg-Zn is better resistant to the oxidation of the essential metals Mg, Zn, and Al. The immersion tests in the HBSS solution further show that the 1 wt.% TC4 composite has the lowest rise of pH values after 14 days, and EDS for the corroded surface signifies that Mg is the main element vulnerable to oxidation by corrosion.
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Affiliation(s)
- Song-Jeng Huang
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106336, Taiwan; (J.-H.F.); (M.S.)
| | - Chuan Li
- Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei 112304, Taiwan
| | - Jun-Hang Feng
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106336, Taiwan; (J.-H.F.); (M.S.)
| | - Sivakumar Selvaraju
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106336, Taiwan; (J.-H.F.); (M.S.)
| | - Murugan Subramani
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106336, Taiwan; (J.-H.F.); (M.S.)
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Yu S, Chou TH, Bose S, Cook J, Park J, Johnston ML. A Reconfigurable Tri-Mode Frequency-Locked Loop Readout Circuit for Biosensor Interfaces. IEEE Trans Biomed Circuits Syst 2023; 17:768-781. [PMID: 37347623 PMCID: PMC10668580 DOI: 10.1109/tbcas.2023.3288505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
In this article, a frequency-locked loop (FLL) based multimodal readout integrated circuit (IC) for interfacing with off-chip temperature, electrochemical, and pH sensors is presented. By reconfiguring its switched-capacitor feedback network, the readout circuit is able to measure resistance, current, and voltage without additional active analog front-end circuits. A prototype IC was fabricated in a 0.18 μm CMOS process. Measured results show that when measuring resistance, the input-referred resistance resolution is 10.5 Ω for 100 Hz integration bandwidth. Using an off-chip thermistor, the readout circuit covers a temperature range of 0-75 °C and achieves an equivalent temperature resolution of 16.4 mKrms. In current mode, the readout circuit has an input range of 0.5μA and an input-referred current noise as low as 40.6 pArms for 100 Hz bandwidth. Interfacing with an on-chip potentiostat, glucose chronoamperometry is demonstrated. In voltage mode, a minimum input-referred voltage noise of 31.7 μVrms is achieved, and the IC can measure a pH range from 1.6 to 12 using a commercial pH probe. At a 1.2 V supply, power consumption of the readout circuit is below 10 μW for all three measurement modes. Additionally, the prototype IC includes an integrated wireless transmitter that implements on-off keying modulation, and a wireless multimodal sensing system utilizing the FLL-based readout circuit is demonstrated.
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Lazaro A, Villarino R, Lazaro M, Canellas N, Prieto-Simon B, Girbau D. Recent Advances in Batteryless NFC Sensors for Chemical Sensing and Biosensing. Biosensors (Basel) 2023; 13:775. [PMID: 37622861 PMCID: PMC10452174 DOI: 10.3390/bios13080775] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/26/2023]
Abstract
This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed.
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Affiliation(s)
- Antonio Lazaro
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain; (R.V.); (M.L.); (N.C.); (B.P.-S.); (D.G.)
| | - Ramon Villarino
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain; (R.V.); (M.L.); (N.C.); (B.P.-S.); (D.G.)
| | - Marc Lazaro
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain; (R.V.); (M.L.); (N.C.); (B.P.-S.); (D.G.)
| | - Nicolau Canellas
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain; (R.V.); (M.L.); (N.C.); (B.P.-S.); (D.G.)
| | - Beatriz Prieto-Simon
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain; (R.V.); (M.L.); (N.C.); (B.P.-S.); (D.G.)
- Catalan Institution for Research and Advanced Studies (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - David Girbau
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain; (R.V.); (M.L.); (N.C.); (B.P.-S.); (D.G.)
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Doering M, Kieninger J, Kübler J, Hofmann U, Rupitsch SJ, Urban G, Weltin A. Advanced electrochemical potential monitoring for improved understanding of electrical neurostimulation protocols. J Neural Eng 2023. [PMID: 37307808 DOI: 10.1088/1741-2552/acdd9d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
OBJECTIVE 
Current-controlled neurostimulation is increasingly used in the clinical treatment of neurological disorders and widely applied in neural prostheses such as cochlear implants. Despite its importance, time-dependent potential traces of electrodes during microsecond-scale current pulses, especially with respect to an electrochemical reference scale, are not precisely understood. However, this knowledge is critical to predict contributions of chemical reactions at the electrodes, and ultimately electrode stability, biocompatibility, and stimulation safety and efficacy.
Approach.
We assessed the electrochemistry of neurostimulation protocols with Pt microelectrodes from millisecond (classical electroanalysis) to microsecond (neurostimulation) timescales. We developed a dual-channel instrumentation amplifier to include a reference electrode in neurostimulation setups. Uniquely, we combined potential measurements with potentiostatic prepolarization to control and investigate the surface status, which is not possible in typical stimulation setups.
Main results.
We thoroughly validated the instrumentation and highlighted the importance of monitoring individual electrochemical electrode potentials in different configurations of neurostimulation. We investigated electrode processes such as oxide formation and oxygen reduction by chronopotentiometry, bridging the gap between milli- and microsecond timescales. Our results demonstrate how much impact on potential traces the electrode's initial surface state and electrochemical surface processes have, even on a microsecond scale.
Significance.
Our unique use of preconditioning in combination with stimulation reveals that interpreting potential traces with respect to electrode processes is misleading without rigorous control of the electrode's surface state. Especially in vivo, where the microenvironment is unknown, simply measuring the voltage between two electrodes cannot accurately reflect the electrode's state and processes. Potential boundaries determine charge transfer, corrosion, and alterations of the electrode/tissue interface such as pH and oxygenation, particularly in long-term in vivo use. Our findings are relevant for all use-cases of constant-current stimulation, strongly advocating for electrochemical in situ investigations in many applications like the development of new electrode materials and stimulation methods.
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Affiliation(s)
- Moritz Doering
- University of Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, Baden-Württemberg, 79110, GERMANY
| | - Jochen Kieninger
- University of Freiburg, Georges-Köhler-Allee 106, Freiburg im Breisgau, Baden-Württemberg, 79110, GERMANY
| | - Julian Kübler
- University of Freiburg, Georges-Köhler-Allee 106, Freiburg im Breisgau, Baden-Württemberg, 79110, GERMANY
| | - Ulrich Hofmann
- Neurosurgery, Medical Center-University of Freiburg, Engesserstr. 4, Freiburg, Freiburg, 79108, GERMANY
| | - Stefan J Rupitsch
- University of Freiburg, Georges-Köhler-Allee 106, Freiburg, 79110, GERMANY
| | - Gerald Urban
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, 79110, GERMANY
| | - Andreas Weltin
- IMTEK - Department of Microsystems Engineering, University of Freiburg, Georges-Köhler-Allee 103, Freiburg im Breisgau, 79110, GERMANY
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Adiraju A, Munjal R, Viehweger C, Al-Hamry A, Brahem A, Hussain J, Kommisetty S, Jalasutram A, Tegenkamp C, Kanoun O. Towards Embedded Electrochemical Sensors for On-Site Nitrite Detection by Gold Nanoparticles Modified Screen Printed Carbon Electrodes. Sensors (Basel) 2023; 23:2961. [PMID: 36991672 PMCID: PMC10054825 DOI: 10.3390/s23062961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 02/28/2023] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
The transition of electrochemical sensors from lab-based measurements to real-time analysis requires special attention to different aspects in addition to the classical development of new sensing materials. Several critical challenges need to be addressed including a reproducible fabrication procedure, stability, lifetime, and development of cost-effective sensor electronics. In this paper, we address these aspects exemplarily for a nitrite sensor. An electrochemical sensor has been developed using one-step electrodeposited (Ed) gold nanoparticles (EdAu) for the detection of nitrite in water, which shows a low limit of detection of 0.38 µM and excellent analytical capabilities in groundwater. Experimental investigations with 10 realized sensors show a very high reproducibility enabling mass production. A comprehensive investigation of the sensor drift by calendar and cyclic aging was carried out for 160 cycles to assess the stability of the electrodes. Electrochemical impedance spectroscopy (EIS) shows significant changes with increasing aging inferring the deterioration of the electrode surface. To enable on-site measurements outside the laboratory, a compact and cost-effective wireless potentiostat combining cyclic and square wave voltammetry, and EIS capabilities has been designed and validated. The implemented methodology in this study builds a basis for the development of further on-site distributed electrochemical sensor networks.
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Affiliation(s)
- Anurag Adiraju
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Rohan Munjal
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Christian Viehweger
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Ammar Al-Hamry
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Amina Brahem
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Jawaid Hussain
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Sanhith Kommisetty
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Aditya Jalasutram
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Christoph Tegenkamp
- Analysis of Solid Surfaces, Institute for Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany
| | - Olfa Kanoun
- Chair Measurement and Sensor Technology, Department of Electrical Engineering and Information Technology, Chemnitz University of Technology, 09107 Chemnitz, Germany
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Setiyono R, Lestari TFH, Anggraeni A, Hartati YW, Bahti HH. UnpadStat Design: Portable Potentiostat for Electrochemical Sensing Measurements Using Screen Printed Carbon Electrode. Micromachines (Basel) 2023; 14:268. [PMID: 36837970 PMCID: PMC9964455 DOI: 10.3390/mi14020268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/14/2023] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
In this research a portable potentiostat was built for electrochemical sensing measurements with three electrodes, specifically SPCEs. The circuit uses a microcontroller as the main controller to manage all activities, starting from adjusting the input voltage for the SPCEs, setting measurement parameters, measuring the resulting current, displaying graphics on the touch screen, sending data to the computer via the USB port, and connecting to the SD card. Measurements and errors with cyclic voltammetry techniques have been compared with commercial potentiostats. The measurement results on a dummy circuit and commercial SPCEs have an accuracy of more than 90% compared to commercial potentiostats. In addition, measurement data can also be saved to an SD card in .CSV format for further purposes.
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Affiliation(s)
- Riyanto Setiyono
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jatinangor 45363, Indonesia
- Department of Electrical Engineering, Faculty of Engineering, Langlangbuana University, Bandung 40162, Indonesia
| | - Tias Febriana Hanifa Lestari
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jatinangor 45363, Indonesia
| | - Anni Anggraeni
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jatinangor 45363, Indonesia
| | - Yeni Wahyuni Hartati
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jatinangor 45363, Indonesia
| | - Husein Hernadi Bahti
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jatinangor 45363, Indonesia
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Demirhan A, Eksin E, Kilic Y, Erdem A. Low-Cost High-Resolution Potentiostat for Electrochemical Detection of Nucleic Acids and Biomolecular Interactions. Micromachines (Basel) 2022; 13:1610. [PMID: 36295963 PMCID: PMC9610652 DOI: 10.3390/mi13101610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/13/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
A handheld USB-powered instrument developed for the electrochemical detection of nucleic acids and biomolecular interactions is presented. The proposed instrument is capable of scanning ± 2.25 V while measuring currents up to ±10 mA, with a minimum current resolution of 6.87 pA. Therefore, it is suitable for nucleic acid sensors, which have high background currents. A low-cost microcontroller with an on-chip 16-bit analog-to-digital converter, 12-bit digital-to-analog converter, and a built-in USB controller were used to miniaturize the system. The offset voltages and gain errors of the analog peripherals were calibrated to obtain a superior performance. Thus, a similar performance to those of the market-leader potentiostats was achieved, but at a fraction of their cost and size. The performance of the application of this proposed architecture was tested successfully and was found to be similar to a leading commercial device through a clinical application in the aspects of the detection of nucleic acids, such as calf thymus ssDNA and dsDNA, and their interactions with a protein (BSA) by using single-use graphite electrodes in combination with the differential pulse voltammetry technique.
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Affiliation(s)
- Alper Demirhan
- Department of Biotechnology, Graduate School of Natural and Applied Sciences, Ege University, Izmir 35100, Turkey
| | - Ece Eksin
- Department of Analytical Chemistry, Faculty of Pharmacy, Ege University, Izmir 35100, Turkey
| | - Yalin Kilic
- Department of Biomedical Engineering, Izmir University of Economics, Izmir 35330, Turkey
- Solar Biyoteknoloji Ltd. (SolarBiotec), Bayrakli, Izmir 35530, Turkey
| | - Arzum Erdem
- Department of Analytical Chemistry, Faculty of Pharmacy, Ege University, Izmir 35100, Turkey
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Lazaro A, Villarino R, Lazaro M, Canellas N, Prieto-Simon B, Girbau D. Battery-Less NFC Potentiostat for Electrochemical Point-of-Care Sensors Based on COTS Components. Sensors (Basel) 2022; 22:7213. [PMID: 36236310 PMCID: PMC9573601 DOI: 10.3390/s22197213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
This work studies the feasibility of using a battery-less Near-Field Communication (NFC) potentiostat for the next generation of electrochemical point-of-care sensors. A design based on an NFC microchip, a microcontroller, and a custom potentiostat based on an operational amplifier is presented. A proof-of-concept prototype has been designed and used to quantify glucose concentration using commercial glucose test strips from chronoamperometry measurements. The device is harvested and the sensor is read using a mobile phone. The prototype uses an antenna loop covered with ferrite sheets to ensure stable operation of the electronics when the mobile phone is used as reader. The use of ferrite reduces the detuning caused by the proximity of the metal parts of the mobile phone. A comparison with a commercial glucometer device is provided. Results obtained using a commercial glucometer and those provided by the proposed potentiostat show an excellent agreement.
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Affiliation(s)
- Antonio Lazaro
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain
| | - Ramon Villarino
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain
| | - Marc Lazaro
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain
| | - Nicolau Canellas
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain
| | - Beatriz Prieto-Simon
- Catalan Institution for Research and Advanced Studies (ICREA), Passeig de Lluís Companys 23, 08010 Barcelona, Spain
| | - David Girbau
- Department of Electronics, Electrics and Automatic Control Engineering, Rovira i Virgili University, 43007 Tarragona, Spain
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Abstract
Objective. Neural interfaces often rely on charge transfer processes between electrodes and the tissue or electrolyte. Electrochemical processes are at the core of electrode function and, therefore, the key to neural interface stability, electrode performance characterization, and utilization of electrodes as chemical sensors. Electrochemical techniques offer a variety of options to investigate the charge transfer and electrocatalytic properties of electrodes.Approach. In this tutorial, we present various experiments to illustrate the power of electrochemical methods, serve as a reference and guideline, and stimulate deeper understanding of the subject.Main results.As a basis for the following experiments, we discuss the platinum cyclic voltammogram and focus on understanding surface processes and roughness determination. We highlight the importance of appropriate instrumentation using potentiostats and how strongly it can influence results. We then discuss a number of potential-controlled and current-controlled methods for electrode characterization, including chronocoulometry, chronoamperometry, (active) potentiometry, and chronopotentiometry. They illustrate charge transfer caused by both electrode surface processes and the presence of redox-active species, such as dissolved oxygen and hydrogen, or hydrogen peroxide. We also discuss the electrode potential with respect to a reference electrode under various conditions and how it affects its electrochemical properties like surface state, catalytic properties and capability to transfer charge.Significance.Electrochemical methods are still underutilized in neural engineering, and valuable information is therefore often not accessed. Many studies on electrode characterization would benefit from a more consistent and target-oriented electrochemical methodology and instrumentation. That ranges from the investigation of new materials and processes, over electrode performance assessment to the development of more long-term stable and biocompatible neural interfaces. Ultimately, standardization, consistency and comparability will play a key role in the translation of microtechnology into biomedical and clinical applications.
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Affiliation(s)
- Andreas Weltin
- Laboratory for Sensors, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
| | - Jochen Kieninger
- Laboratory for Sensors, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany.,BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany
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Alam AU, Clyne D, Deen MJ. A Low-Cost Multi-Parameter Water Quality Monitoring System. Sensors (Basel) 2021; 21:3775. [PMID: 34072361 DOI: 10.3390/s21113775] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/14/2021] [Accepted: 05/26/2021] [Indexed: 11/17/2022]
Abstract
Multi-parameter water quality monitoring is crucial in resource-limited areas to provide persistent water safety. Conventional water monitoring techniques are time-consuming, require skilled personnel, are not user-friendly and are incompatible with operating on-site. Here, we develop a multi-parameter water quality monitoring system (MWQMS) that includes an array of low-cost, easy-to-use, high-sensitivity electrochemical sensors, as well as custom-designed sensor readout circuitry and smartphone application with wireless connectivity. The system overcomes the need of costly laboratory-based testing methods and the requirement of skilled workers. The proposed MWQMS system can simultaneously monitor pH, free chlorine, and temperature with sensitivities of 57.5 mV/pH, 186 nA/ppm and 16.9 mV/°C, respectively, as well as sensing of BPA with <10 nM limit of detection. The system also provides seamless interconnection between transduction of the sensors' signal, signal processing, wireless data transfer and smartphone app-based operation. This interconnection was accomplished by fabricating nanomaterial and carbon nanotube-based sensors on a common substrate, integrating these sensors to a readout circuit and transmitting the sensor data to an Android application. The MWQMS system provides a general platform technology where an array of other water monitoring sensors can also be easily integrated and programmed. Such a system can offer tremendous opportunity for a broad range of environmental monitoring applications.
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Fedtschenko T, Utz A, Stanitzki A, Hennig A, Lüdecke A, Haas N, Kokozinski R. A New Configurable Wireless Sensor System for Biomedical Applications with ISO 18000-3 Interface in 0.35 µm CMOS. Sensors (Basel) 2019; 19:E4110. [PMID: 31547579 DOI: 10.3390/s19194110] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/09/2019] [Accepted: 09/18/2019] [Indexed: 02/01/2023]
Abstract
This article presents a new configurable wireless sensor system. The system is used to perform amperometric measurements and send the measurement data to a handheld reader using a wireless transponder interface. The two-chip sensor system was implemented in a 0.35 μm CMOS technology. The system consists of an integrated nano-potentiostat that performs the actual measurements and an ISO 18000-3 compliant frontend that enables wireless telemetric data transmission and powering of the entire sensor system. The system was manufactured in combination with a chronoamperometric glucose sensor which allows the measurement of the glucose content in tear fluid and thus a non-invasive determination of the blood sugar level. For a range of sensor currents from 0.1 μA to 10 μA, the potentiostat achieved an accuracy of better than 5 % with a total power dissipation of less than 600 μW. With the realized antenna geometry a wireless communication distance of more than 7 cm has been achieved.
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12
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Jenkins DM, Kurasaki R. ABE-VIEW: Android Interface for Wireless Data Acquisition and Control. Sensors (Basel) 2018; 18:E2647. [PMID: 30104474 DOI: 10.3390/s18082647] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/04/2018] [Accepted: 08/09/2018] [Indexed: 01/19/2023]
Abstract
Advances in scientific knowledge are increasingly supported by a growing community of developers freely sharing new hardware and software tools. In this spirit we have developed a free Android app, ABE-VIEW, that provides a flexible graphical user interface (GUI) populated entirely from a remote instrument by ascii-coded instructions communicated wirelessly over Bluetooth. Options include an interactive chart for plotting data in real time, up to 16 data fields, and virtual controls including buttons, numerical controls with user-defined range and resolution, and radio buttons which the user can use to send coded instructions back to the instrument. Data can be recorded into comma delimited files interactively at the user’s discretion. Our original objective of the project was to make data acquisition and control for undergraduate engineering labs more modular and affordable, but we have also found that the tool is highly useful for rapidly testing novel sensor systems for iterative improvement. Here we document the operation of the app and syntax for communicating with it. We also illustrate its application in undergraduate engineering labs on dynamic systems modeling, as well as for identifying the source of harmonic distortion affecting electrochemical impedance measurements at certain frequencies in a novel wireless potentiostat.
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Aznar-Poveda J, Lopez-Pastor JA, Garcia-Sanchez AJ, Garcia-Haro J, Otero TF. A COTS-Based Portable System to Conduct Accurate Substance Concentration Measurements. Sensors (Basel) 2018; 18:E539. [PMID: 29439424 DOI: 10.3390/s18020539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/01/2018] [Accepted: 02/07/2018] [Indexed: 02/04/2023]
Abstract
Traditionally, electrochemical procedures aimed at determining substance concentrations have required a costly and cumbersome laboratory environment. Specialized equipment and personnel obtain precise results under complex and time-consuming settings. Innovative electrochemical-based sensors are emerging to alleviate this difficulty. However, they are generally scarce, proprietary hardware and/or software, and focused only on measuring a restricted range of substances. In this paper, we propose a portable, flexible, low-cost system, built from commercial off-the-shelf components and easily controlled, using open-source software. The system is completed with a wireless module, which enables the transmission of measurements to a remote database for their later processing. A well-known PGSTAT100 Autolab device is employed to validate the effectiveness of our proposal. To this end, we select ascorbic acid as the substance under consideration, evaluating the reliability figure and obtaining the calibration curves for both platforms. The final outcomes are shown to be feasible, accurate, and repeatable.
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Jung J, Lee J, Shin S, Kim YT. Development of a Telemetric, Miniaturized Electrochemical Amperometric Analyzer. Sensors (Basel) 2017; 17:E2416. [PMID: 29065534 PMCID: PMC5677258 DOI: 10.3390/s17102416] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 10/16/2017] [Accepted: 10/20/2017] [Indexed: 01/14/2023]
Abstract
In this research, we developed a portable, three-electrode electrochemical amperometric analyzer that can transmit data to a PC or a tablet via Bluetooth communication. We performed experiments using an indium tin oxide (ITO) glass electrode to confirm the performance and reliability of the analyzer. The proposed analyzer uses a current-to-voltage (I/V) converter to convert the current generated by the reduction-oxidation (redox) reaction of the buffer solution to a voltage signal. This signal is then digitized by the processor. The configuration of the power and ground of the printed circuit board (PCB) layer is divided into digital and analog parts to minimize the noise interference of each part. The proposed analyzer occupies an area of 5.9 × 3.25 cm² with a current resolution of 0.4 nA. A potential of 0~2.1 V can be applied between the working and the counter electrodes. The results of this study showed the accuracy of the proposed analyzer by measuring the Ruthenium(III) chloride ( Ru III ) concentration in 10 mM phosphate-buffered saline (PBS) solution with a pH of 7.4. The measured data can be transmitted to a PC or a mobile such as a smartphone or a tablet PC using the included Bluetooth module. The proposed analyzer uses a 3.7 V, 120 mAh lithium polymer battery and can be operated for 60 min when fully charged, including data processing and wireless communication.
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Affiliation(s)
- Jaehyo Jung
- IT Fusion Technology Research Center, Department of IT Fusion Technology, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea.
| | - Jihoon Lee
- IT Fusion Technology Research Center, Department of IT Fusion Technology, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea.
| | - Siho Shin
- IT Fusion Technology Research Center, Department of IT Fusion Technology, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea.
| | - Youn Tae Kim
- IT Fusion Technology Research Center, Department of IT Fusion Technology, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea.
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Li H, Liu X, Li L, Mu X, Genov R, Mason AJ. CMOS Electrochemical Instrumentation for Biosensor Microsystems: A Review. Sensors (Basel) 2016; 17:s17010074. [PMID: 28042860 PMCID: PMC5298647 DOI: 10.3390/s17010074] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 11/16/2022]
Abstract
Modern biosensors play a critical role in healthcare and have a quickly growing commercial market. Compared to traditional optical-based sensing, electrochemical biosensors are attractive due to superior performance in response time, cost, complexity and potential for miniaturization. To address the shortcomings of traditional benchtop electrochemical instruments, in recent years, many complementary metal oxide semiconductor (CMOS) instrumentation circuits have been reported for electrochemical biosensors. This paper provides a review and analysis of CMOS electrochemical instrumentation circuits. First, important concepts in electrochemical sensing are presented from an instrumentation point of view. Then, electrochemical instrumentation circuits are organized into functional classes, and reported CMOS circuits are reviewed and analyzed to illuminate design options and performance tradeoffs. Finally, recent trends and challenges toward on-CMOS sensor integration that could enable highly miniaturized electrochemical biosensor microsystems are discussed. The information in the paper can guide next generation electrochemical sensor design.
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Affiliation(s)
- Haitao Li
- Maxim Integrated Products Inc., 160 Rio Robles, San Jose, CA 95134, USA.
| | - Xiaowen Liu
- Xcellcure LLC., 1 City Place Drive Suite 285, St. Louis, MO 63131, USA.
| | - Lin Li
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA.
| | - Xiaoyi Mu
- Apple Inc., 1 Infinite Loop, Cupertino, CA 95014, USA.
| | - Roman Genov
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S, Canada.
| | - Andrew J Mason
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA.
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Nayak RS, Shafiuddin B, Pasha A, Vinay K, Narayan A, Shetty SV. Comparison of Galvanic Currents Generated Between Different Combinations of Orthodontic Brackets and Archwires Using Potentiostat: An In Vitro Study. J Int Oral Health 2015; 7:29-35. [PMID: 26229367 PMCID: PMC4513772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/16/2015] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Technological advances in wire selection and bracket design have led to improved treatment efficiency and allowed longer time intervals between appliance adjustments. The wires remain in the mouth for a longer duration and are subjected to electrochemical reactions, mechanical forces of mastication and generalized wear. These cause different types of corrosion. This study was done to compare the galvanic currents generated between different combinations of brackets and archwires commonly used in orthodontic practices. MATERIALS AND METHODS The materials used for the study included different commercially available orthodontic archwires and brackets. The galvanic current generated by individual materials and different combinations of these materials was tested and compared. The orthodontic archwires used were 0.019″ × 0.025″ heat-activated nickel-titanium (3M Unitek), 0.019″ × 0.025″ beta-titanium (3M Unitek) and 0.019″ × 0.025″ stainless steel (3M Unitek). The orthodontic brackets used were 0.022″ MBT laser-cut (Victory Series, 3M Unitek) and metal-injection molded (Leone Company) maxillary central incisor brackets respectively. The ligature wire used for ligation was 0.009″ stainless steel ligature (HP Company). The galvanic current for individual archwires, brackets, and the different bracket-archwire-ligature combinations was measured by using a Potentiostat machine. The data were generated using the Linear Sweep Voltammetry and OriginPro 8.5 Graphing and Data Analysis Softwares. The study was conducted in two phases. Phase I comprised of five groups for open circuit potential (OCP) and galvanic current (I), whereas Phase II comprised of six groups for galvanic current alone. RESULTS Mean, standard deviation and range were computed for the OCP and galvanic current (I) values obtained. Results were subjected to statistical analysis through ANOVA. In Phase I, higher mean OCP was recorded in stainless steel archwire, followed by beta-titanium archwire, heat-activated nickel titanium archwire, laser-cut bracket and metal-injection molded bracket, respectively. The difference in mean OCP recorded among the groups was found to be statistically significant in aerated phosphate buffered saline solution. The galvanic current (I) for metal-injection molded stainless steel brackets showed significantly higher values than all the other materials. Phase II results suggested that, in the couples formed by the archwire-bracket-ligature combinations, the bracket had more important contribution to the total galvanic current generated, since there were significant differences between galvanic current among the 2 brackets tested but not among the 3 wires. The galvanic current of the metal-injection molded bracket was significantly higher than that of laser-cut bracket. Highest mean current (I) was recorded in metal-injection molded bracket when used with heat-activated nickel titanium archwire while lowest mean current (I) was recorded in laser-cut bracket when used with beta-titanium archwire. CONCLUSION The present study concluded that the bracket emerged to be the most important factor in determining the galvanic current (I). Higher mean current (I) was recorded in metal-injection molded bracket compared to laser-cut bracket. Among the three archwires, higher mean current (I) was recorded in heat-activated nickel-titanium, followed by stainless-steel and beta-titanium respectively. When coupled together; highest mean current (I) was recorded in metal-injection molded bracket when used with heat-activated nickel titanium archwire while lowest mean current (I) was recorded in laser-cut bracket when used with beta-titanium archwire.
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Affiliation(s)
- Rabindra S Nayak
- Professor and Head, Department of Orthodontics, MR Ambedkar Dental College, Bengaluru, Karnataka, India
| | - Bareera Shafiuddin
- Postgraduate Student, Department of Orthodontics, MR Ambedkar Dental College, Bengaluru, Karnataka, India,Correspondence: Dr. Shafiuddin B. Department of Orthodontics, MR Ambedkar Dental College, 1/36, Cline Road, Cooke Town, Bengaluru - 560 005, Karnataka, India.
| | - Azam Pasha
- Professor, Department of Orthodontics, MR Ambedkar Dental College, Bengaluru, Karnataka, India
| | - K Vinay
- Reader, Department of Orthodontics, MR Ambedkar Dental College, Bengaluru, Karnataka, India
| | - Anjali Narayan
- Reader, Department of Orthodontics, MR Ambedkar Dental College, Bengaluru, Karnataka, India
| | - Smitha V Shetty
- Lecturer, Department of Orthodontics, MR Ambedkar Dental College, Bengaluru, Karnataka, India
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Kim J, Maitra RD, Pedrotti K, Dunbar WB. Detecting single-abasic residues within a DNA strand immobilized in a biological nanopore using an integrated CMOS sensor. Sens Actuators B Chem 2013; 177:1075-1082. [PMID: 24496266 PMCID: PMC3564666 DOI: 10.1016/j.snb.2012.11.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this paper, we demonstrate the application of a novel current-measuring sensor (CMS) customized for nanopore applications. The low-noise CMS is fabricated in a 0.35μm CMOS process and is implemented in experiments involving DNA captured in an α-hemolysin (α-HL) nanopore. Specifically, the CMS is used to build a current amplitude map as a function of varying positions of a single-abasic residue within a homopolymer cytosine single-stranded DNA (ssDNA) that is captured and held in the pore. Each ssDNA is immobilized using a biotin-streptavidin linkage. Five different DNA templates are measured and compared: one all-cytosine ssDNA, and four with a single-abasic residue substitution that resides in or near the ~1.5nm aperture of the α-HL channel when the strand is immobilized. The CMOS CMS is shown to resolves the ~5Å displacements of the abasic residue within the varying templates. The demonstration represents an advance in application-specific circuitry that is optimized for small-footprint nanopore applications, including genomic sequencing.
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Affiliation(s)
- Jungsuk Kim
- Department of Computer Engineering, University of California at Santa Cruz, Santa Cruz, CA 95064, U.S.A
| | - Raj D Maitra
- Department of Computer Engineering, University of California at Santa Cruz, Santa Cruz, CA 95064, U.S.A
| | - Ken Pedrotti
- Department of Electrical Engineering, University of California at Santa Cruz, Santa Cruz, CA 95064, U.S.A
| | - William B Dunbar
- Department of Computer Engineering, University of California at Santa Cruz, Santa Cruz, CA 95064, U.S.A
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Wang WS, Huang HY, Chen SC, Ho KC, Lin CY, Chou TC, Hu CH, Wang WF, Wu CF, Luo CH. Real-time telemetry system for amperometric and potentiometric electrochemical sensors. Sensors (Basel) 2011; 11:8593-610. [PMID: 22164093 DOI: 10.3390/s110908593] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 08/29/2011] [Accepted: 09/01/2011] [Indexed: 11/30/2022]
Abstract
A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC), a microcontroller unit (MCU), a graphical user interface (GUI), and a radio frequency (RF) transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA) to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA). The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR) greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment), a small size of 5.6 cm × 8.7 cm, high portability, and high integration.
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Alonso GA, Dominguez RB, Marty JL, Muñoz R. An approach to an inhibition electronic tongue to detect on-line organophosphorus insecticides using a computer controlled multi-commuted flow system. Sensors (Basel) 2011; 11:3791-802. [PMID: 22163822 PMCID: PMC3231336 DOI: 10.3390/s110403791] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 03/22/2011] [Accepted: 03/24/2011] [Indexed: 11/16/2022]
Abstract
An approach to an inhibition bioelectronic tongue is presented. The work is focused on development of an automated flow system to carry out experimental assays, a custom potentiostat to measure the response from an enzymatic biosensor, and an inhibition protocol which allows on-line detections. A Multi-commuted Flow Analysis system (MCFA) was selected and developed to carry out assays with an improved inhibition method to detect the insecticides chlorpyrifos oxon (CPO), chlorfenvinfos (CFV) and azinphos methyl-oxon (AZMO). The system manifold comprised a peristaltic pump, a set of seven electronic valves controlled by a personal computer electronic interface and software based on LabView® to control the sample dilutions into the cell. The inhibition method consists in the injection of the insecticide when the enzyme activity has reached the plateau of the current; with this method the incubation time is avoided. A potentiostat was developed to measure the response from the enzymatic biosensor. Low limits of detection of 10 nM for CPO, CFV, and AZMO were achieved.
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Affiliation(s)
- Gustavo A. Alonso
- Centro de Investigación y de Estudios Avanzados del Intituto Politecnico Nacional, Av. Instituto Politécnico Nacional 2508, Mexico; E-Mails: (R.B.D.); (R.M.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +52-55-57473800 ext. 6210
| | - Rocio B. Dominguez
- Centro de Investigación y de Estudios Avanzados del Intituto Politecnico Nacional, Av. Instituto Politécnico Nacional 2508, Mexico; E-Mails: (R.B.D.); (R.M.)
| | - Jean-Louis Marty
- Université de Perpignan Via Domitia, IMAGES EA4218, Centre de Phytopharmacie, 52 Avenue Paul Alduy, 66860 Perpignan Cedex, France; E-Mail:
| | - Roberto Muñoz
- Centro de Investigación y de Estudios Avanzados del Intituto Politecnico Nacional, Av. Instituto Politécnico Nacional 2508, Mexico; E-Mails: (R.B.D.); (R.M.)
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Wang WS, Kuo WT, Huang HY, Luo CH. Wide dynamic range CMOS potentiostat for amperometric chemical sensor. Sensors (Basel) 2010; 10:1782-97. [PMID: 22294899 DOI: 10.3390/s100301782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/01/2010] [Accepted: 02/02/2010] [Indexed: 11/17/2022]
Abstract
Presented is a single-ended potentiostat topology with a new interface connection between sensor electrodes and potentiostat circuit to avoid deviation of cell voltage and linearly convert the cell current into voltage signal. Additionally, due to the increased harmonic distortion quantity when detecting low-level sensor current, the performance of potentiostat linearity which causes the detectable current and dynamic range to be limited is relatively decreased. Thus, to alleviate these irregularities, a fully-differential potentiostat is designed with a wide output voltage swing compared to single-ended potentiostat. Two proposed potentiostats were implemented using TSMC 0.18-μm CMOS process for biomedical application. Measurement results show that the fully differential potentiostat performs relatively better in terms of linearity when measuring current from 500 pA to 10 uA. Besides, the dynamic range value can reach a value of 86 dB.
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Abstract
A low-noise potentiostat, developed and built at NBS, is described. The instrument, which has built-in an ac current amplifier, is particularly suited for detecting small current fluctuations in the frequency range between 0.1 and 2000 Hz. The noise in the dc control voltage is of the order of 2.5 × 10-8 V/√Hz, and the instability of the ac amplifier corresponds to a signal of 3 × 10-11 A/√Hz. The performance characteristics of the instrument are fully described as well as its use in impedance measurements by means of a swept frequency signal. The instrument can also be used as a galvanostat.
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Affiliation(s)
- R W Shideler
- National Bureau of Standards, Washington, D.C. 20234
| | - U Bertocci
- National Bureau of Standards, Washington, D.C. 20234
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Davis RS, Bower VE. A Novel Method for Analyzing Silver Sediment With High Precision. J Res Natl Bur Stand (1977) 1979; 84:157-160. [PMID: 34880512 PMCID: PMC6752650 DOI: 10.6028/jres.084.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023] Open
Abstract
A technique has been devised which is sufficiently accurate to aid in an electrochemical determination of the Faraday constant using the silver coulometer. The technique is used to recover the silver residue which falls from the anode during operation of the silver coulometer. In contrast to previous efforts at recovery, which involved weighing of the silver residue, the method here described is to convert the silver atoms to ions and then to plate the silver onto a cathode held at constant potential with respect to a reference electrode. The current involved in the electrolysis is integrated electronically. An overall standard deviation of 5 μg is achieved for samples ranging in size from 400 μg to 1.8 mg.
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Affiliation(s)
- R S Davis
- Center for Absolute Physical Quantities, National Bureau of Standards, Washington, DC 20234
| | - V E Bower
- Center for Absolute Physical Quantities, National Bureau of Standards, Washington, DC 20234
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Abstract
A system, utilizing a microprocessor, intended for the control and unattended operation of a standard laboratory potentiostat is described. The system consists of a central processing unit, 16 kilobytes of random access memory, peripheral interfacing, a timer and digital to analog and analog to digital converters. It allows flexible operation of the potentiostat by programming of the central processor.
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Affiliation(s)
- M I Cohen
- National Measurement Laboratory, National Bureau of Standards, Washington, D. C. 20234
| | - P A Heimann
- National Measurement Laboratory, National Bureau of Standards, Washington, D. C. 20234
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