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Amperometric Sensing
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Amperometric Sensing

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (15 November 2020) | Viewed by 26592

Special Issue Editors

Dr. Maria Rachele Guascito

E-Mail Website
Guest Editor
Università del Salento, c/o Campus Ecotekne, Lecce, Italy
Interests: electrochemistry, (bio)sensors, surface analysis, thin (bio)films, nano materials, CMEs
Dr. Francesco Milano

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Guest Editor
Consiglio Nazionale delle Ricerche, Rome, Italy
Interests: proteins, photosynthesis, drug delivery, (bio)sensors, electrochemistry, thin (bio)films
Dr. Livia Giotta

E-Mail Website
Guest Editor
Department of Biological and Environmental Sciences and Technologies, University of Salento, via Monteroni, 73100 Lecce, Italy
Interests: chemical sensors; photoactive proteins; thin organic films; infrared spectroscopy; liposomes

Special Issue Information

Dear Colleagues,

In modern society, there is an increasing demand for selective, fast, low-cost, portable, and user-friendly detection methods for a wide range of target molecules of interest for human health, environment, and food industries.

The above-mentioned characteristics can be met by Amperometric Sensing  technology, which combines innovations in material science (i.e., micro- and nano-structures) with electrochemical and analytical methods that are rapidly evolving.

Concomitantly with the development of novel electrode materials, the optimization of the sensing system has become more complex, requiring competences in several qualified fields spanning from chemistry, biology, physics, and molecular biology, to nanotechnology, micro-fabrication, and electronic engineering. Although much research has been carried out so far in this area, many technological aspects remain to be optimized and represent open challenges for the scientific community. In particular, recent efforts are aimed at fulfilling the request of miniaturized, wearable, and disposable devices.

This Special Issue invites original research papers and review articles aiming to discuss the key points of the development and use of amperometric sensing systems by pointing out both the merits and limits they present.

Dr. Guascito Maria Rachele
Dr. Francesco Milano
Dr. Livia Giotta
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • (Bio)sensor 
  • Amperometric detection 
  • Modified electrodes 
  • New electrode materials 
  • Enzymatic
  • Non-enzymatic 
  • Lab-on-chip
  • Microfluidic

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Published Papers (4 papers)

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Research

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16 pages, 3569 KiB  
Article
Numerical Modeling and Investigation of Amperometric Biosensors with Perforated Membranes
by Seyed Mohsen Hashem Zadeh, Mohammadhosein Heidarshenas, Mohammad Ghalambaz, Aminreza Noghrehabadi and Mohsen Saffari Pour
Sensors 2020, 20(10), 2910; https://doi.org/10.3390/s20102910 - 21 May 2020
Cited by 11 | Viewed by 3569
Abstract
The present paper aims to investigate the influence of perforated membrane geometry on the performance of biosensors. For this purpose, a 2-D axisymmetric model of an amperometric biosensor is analyzed. The governing equations describing the reaction-diffusion equations containing a nonlinear term related to [...] Read more.
The present paper aims to investigate the influence of perforated membrane geometry on the performance of biosensors. For this purpose, a 2-D axisymmetric model of an amperometric biosensor is analyzed. The governing equations describing the reaction-diffusion equations containing a nonlinear term related to the Michaelis–Menten kinetics of the enzymatic reaction are introduced. The partial differential governing equations, along with the boundary conditions, are first non-dimensionalized by using appropriate dimensionless variables and then solved in a non-uniform unstructured grid by employing the Galerkin Finite Element Method. To examine the impact of the hole-geometry of the perforated membrane, seven different geometries—including cylindrical, upward circular cone, downward circular cone, upward paraboloid, downward paraboloid, upward concave paraboloid, and downward concave paraboloid—are studied. Moreover, the effects of the perforation level of the perforated membrane, the filling level of the enzyme on the transient and steady-state current of the biosensor, and the half-time response are presented. The results of the simulations show that the transient and steady-state current of the biosensor are affected by the geometry dramatically. Thus, the sensitivity of the biosensor can be influenced by different hole-geometries. The minimum and maximum output current can be obtained from the cylindrical and upward concave paraboloid holes. On the other hand, the least half-time response of the biosensor can be obtained in the cylindrical geometry. Full article
(This article belongs to the Special Issue Amperometric Sensing)
►▼ Show Figures

Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Schematic view of the biosensor with cylindrical holes.</p> Full article ">Figure 2
<p>The geometries of the biosensor unit cell: (<b>a</b>) cylindrical, (<b>b</b>) upward circular cone, (<b>c</b>) downward circular cone, (<b>d</b>) upward paraboloid, (<b>e</b>) downward paraboloid, (<b>f</b>) upward concave paraboloid, and (<b>g</b>) downward concave paraboloid. Figures are not to scale.</p> Full article ">Figure 3
<p>Comparison between the results of the present study with [<a href="#B10-sensors-20-02910" class="html-bibr">10</a>]: (<b>a</b>) variation in the dynamic current of the biosensor with the time and thickness of the enzyme membrane (<span class="html-italic">d</span>) for <span class="html-italic">V<sub>max</sub></span> = 10<sup>−7</sup> mol/cm<sup>3</sup>s; (<b>b</b>) dependency of the maximal current of the biosensor on the maximal enzymatic rate (<span class="html-italic">V<sub>max</sub></span>) and the thickness of the enzyme membrane.</p> Full article ">Figure 4
<p>Comparison between the results of the present study with [<a href="#B13-sensors-20-02910" class="html-bibr">13</a>]: (<b>a</b>) concentration profiles of glucose and H<sub>2</sub>O<sub>2</sub> in a multi-layer sensor system consisting of GO<sub>x</sub>/PPD (20 nm) and HAs/Fe<sup>3+</sup> (100 nm); (<b>b</b>) dependency of the maximal current of the biosensor on the glucose concentration with 20 nm of GO<sub>x</sub>/PPD and 100 nm of HAs/Fe<sup>3+</sup>.</p> Full article ">Figure 5
<p>Comparison between the results of the present study and Baronas [<a href="#B20-sensors-20-02910" class="html-bibr">20</a>] in cylindrical geometry for different values of the enzyme filling level (<span class="html-italic">γ</span>) and the perforation level (<span class="html-italic">α</span>): <span class="html-italic">V<sub>max</sub></span> = 100 μM. (1) <span class="html-italic">a</span><sub>1</sub> = 1 μm, <span class="html-italic">S</span><sub>0</sub> = 1 μM; (2) <span class="html-italic">a</span><sub>1</sub> = 0.8 μm, <span class="html-italic">S</span><sub>0</sub> = 100 μM; (3) <span class="html-italic">a</span><sub>1</sub> = 0.4 μm, <span class="html-italic">S</span><sub>0</sub> = 100 μM.</p> Full article ">Figure 6
<p>Comparison between the results of the present study with the experimental data of [<a href="#B31-sensors-20-02910" class="html-bibr">31</a>]; variation in the dynamic current of the biosensor with time and for two substrate concentrations: <span class="html-italic">S</span><sub>0</sub> = 0.49 and 0.99 mol/m<sup>3</sup>.</p> Full article ">Figure 7
<p>Dependency of the output current on the perforation level (<math display="inline"><semantics> <mrow> <mi>γ</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>): (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.2</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics></math>. The enzyme filling level (<math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.5</mn> </mrow> </semantics></math>); (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>γ</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>γ</mi> <mo>=</mo> <mn>0.95</mn> </mrow> </semantics></math>.</p> Full article ">Figure 8
<p>Dependency of the steady-state biosensor current on the perforation level: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>γ</mi> <mo>=</mo> <mn>0.05</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>γ</mi> <mo>=</mo> <mn>0.95</mn> </mrow> </semantics></math>. The enzyme filling level: (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.35</mn> </mrow> </semantics></math>, (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>α</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics></math>.</p> Full article ">Scheme 1
<p>Different regions of an amperometric biosensor.</p> Full article ">
12 pages, 1574 KiB  
Article
KickStat: A Coin-Sized Potentiostat for High-Resolution Electrochemical Analysis
by Orlando S. Hoilett, Jenna F. Walker, Bethany M. Balash, Nicholas J. Jaras, Sriram Boppana and Jacqueline C. Linnes
Sensors 2020, 20(8), 2407; https://doi.org/10.3390/s20082407 - 23 Apr 2020
Cited by 63 | Viewed by 14661
Abstract
The demand for wearable and point-of-care devices has led to an increase in electrochemical sensor development to measure an ever-increasing array of biological molecules. In order to move from the benchtop to truly portable devices, the development of new biosensors requires miniaturized instrumentation [...] Read more.
The demand for wearable and point-of-care devices has led to an increase in electrochemical sensor development to measure an ever-increasing array of biological molecules. In order to move from the benchtop to truly portable devices, the development of new biosensors requires miniaturized instrumentation capable of making highly sensitive amperometric measurements. To meet this demand, we have developed KickStat, a miniaturized potentiostat that combines the small size of the integrated Texas Instruments LMP91000 potentiostat chip (Texas Instruments, Dallas, TX, USA) with the processing power of the ARM Cortex-M0+ SAMD21 microcontroller (Microchip Technology, Chandler, AZ, USA) on a custom-designed 21.6 mm by 20.3 mm circuit board. By incorporating onboard signal processing via the SAMD21, we achieve 1 mV voltage increment resolution and an instrumental limit of detection of 4.5 nA in a coin-sized form factor. This elegant engineering solution allows for high-resolution electrochemical analysis without requiring extensive circuitry. We measured the faradaic current of an anti-cocaine aptamer using cyclic voltammetry and square wave voltammetry and demonstrated that KickStat’s response was within 0.6% of a high-end benchtop potentiostat. To further support others in electrochemical biosensors development, we have made KickStat’s design and firmware available in an online GitHub repository. Full article
(This article belongs to the Special Issue Amperometric Sensing)
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Figure 1

Figure 1
<p>(<b>A</b>) Photograph of the assembled KickStat: Button Cell Rev B. The device features the LMP91000 along with a SAMD21 microcontroller running an Arduino bootloader, (<b>B</b>) functional block diagram of KickStat: Button Cell Rev A highlighting the essential subcomponents, (<b>C</b>) block diagram of the LMP91000 highlighting its internal features and characteristics (diagram recreated from the chip’s datasheet). Details of the LMP91000 can be found in the chip’s datasheet.</p> Full article ">Figure 2
<p>Open circuit current measurements with calculated input-referred noise. Noise decreases as the gain resistor increases.</p> Full article ">Figure 3
<p>Quantitative comparisons between KickStat (blue) and the commercial device (red) while measuring 5 mM potassium ferricyanide with different electrochemical techniques. (<b>a</b>) Cyclic voltammetry, (<b>b</b>) square wave voltammetry, (<b>c</b>) chronoamperometry, and (<b>d</b>) normal pulse voltammetry. Peak values of the current are within 9% for each measurement across each electrochemical technique. Each data point shown for each device is the average of 3 sequential runs. Error bars represent standard deviation and are smaller than the points plotted. Voltages are referenced against an Ag/AgCl reference electrode.</p> Full article ">Figure 4
<p>Qualitative comparisons between KickStat (blue) and the commercial device (red) while measuring cocaine biosensor. (<b>a</b>) Comparative readout of the cyclic voltammogram for the cocaine aptamer in phosphate-buffered saline (PBS) displaying minimal redox peak separation characteristic of an adsorbed species, indicating successful functionalization of the electrode, (<b>b</b>) Cyclic voltammogram with the lower resolution LMP91000 stock voltage reference generator and corresponding points using the commercial device. Peaks are not discernible by eye or by commercial device’s software, making analysis of the electrochemical current virtually impossible, (<b>c</b>) Square wave voltammograms in PBS and 0.5 mM cocaine hydrochloride. Data points shown for each device are the average of 3 sequential runs. Error bars represent standard deviation and are smaller than the points plotted in many cases. Voltages are referenced against an Ag/AgCl reference electrode.</p> Full article ">
11 pages, 1775 KiB  
Article
Development of Flexible Dispense-Printed Electrochemical Immunosensor for Aflatoxin M1 Detection in Milk
by Biresaw Demelash Abera, Aniello Falco, Pietro Ibba, Giuseppe Cantarella, Luisa Petti and Paolo Lugli
Sensors 2019, 19(18), 3912; https://doi.org/10.3390/s19183912 - 11 Sep 2019
Cited by 44 | Viewed by 4421
Abstract
Detection of mycotoxins, especially aflatoxin M1 (AFM1), in milk is crucial to be able to guarantee food quality and safety. In recent years, biosensors have been emerging as a fast, reliable and low-cost technique for the detection of this toxin. In this work, [...] Read more.
Detection of mycotoxins, especially aflatoxin M1 (AFM1), in milk is crucial to be able to guarantee food quality and safety. In recent years, biosensors have been emerging as a fast, reliable and low-cost technique for the detection of this toxin. In this work, flexible biosensors were fabricated using dispense-printed electrodes, which were functionalized with single-walled carbon nanotubes (SWCNTs) and subsequently coated with specific antibodies to improve their sensitivity. Next, the immunosensor was tested for the detection of AFM1 in buffer solution and a spiked milk sample using a chronoamperometric technique. Results showed that the working range of the sensors was 0.01 µg/L at minimum and 1 µg/L at maximum in both buffer and spiked milk. The lower limit of detection of the SWCNT-functionalized sensor was 0.02 µg/L, which indicates an improved sensitivity compared to the sensors reported so far. The sensitivity and detection range were in accordance with the limitation values imposed by regulations on milk and its products. Therefore, considering the low fabrication cost, the ease of operation, and the rapid read-out, the use of this sensor could contribute to safeguarding consumers’ health. Full article
(This article belongs to the Special Issue Amperometric Sensing)
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Figure 1

Figure 1
<p>Schematic diagram of the fabricating process of the biosensors: (<b>A</b>) printing working electrode (WE) and counter electrode (CE), (<b>B</b>) printing WE with AgCl by alignment, (<b>C</b>) spray depositing single-walled carbon nanotubes (SWCNTs), (<b>D</b>) immobilization of antibody, and (<b>E</b>) final biosensor.</p> Full article ">Figure 2
<p>Cyclic voltammetry unfunctionalized vs. functionalized electrode in potassium hexacyanoferrate (III) solution.</p> Full article ">Figure 3
<p>Atomic force micrographs (AFM) of the electrode: (<b>A</b>) unfunctionalized Ag electrode and (<b>B</b>) functionalized electrode with SWCNTs.</p> Full article ">Figure 4
<p>2D profile of the electrode: (<b>A</b>) step height and (<b>B</b>) surface roughness.</p> Full article ">Figure 5
<p>Chronoamperometric measurement of AFM1 in buffer solution; A<sub>0</sub> is the sensor response without AFM1.</p> Full article ">Figure 6
<p>Chronoamperometric measurement of AFM1 in spiked milk sample; A<sub>0</sub> is the sensor response without AFM1.</p> Full article ">

Review

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17 pages, 906 KiB  
Review
Modern Electrode Technologies for Ion and Molecule Sensing
by William S. Skinner and Keat Ghee Ong
Sensors 2020, 20(16), 4568; https://doi.org/10.3390/s20164568 - 14 Aug 2020
Cited by 3 | Viewed by 3122
Abstract
In high concentrations, ionic species can be toxic in the body, catalyzing unwanted bioreactions, inhibiting enzymes, generating free radicals, in addition to having been associated with diseases like Alzheimer’s and cancer. Although ionic species are ubiquitous in the environment in trace amounts, high [...] Read more.
In high concentrations, ionic species can be toxic in the body, catalyzing unwanted bioreactions, inhibiting enzymes, generating free radicals, in addition to having been associated with diseases like Alzheimer’s and cancer. Although ionic species are ubiquitous in the environment in trace amounts, high concentrations of these metals are often found within industrial and agricultural waste runoff. Therefore, it remains a global interest to develop technologies capable of quickly and accurately detecting trace levels of ionic species, particularly in aqueous environments that naturally contain other competing/inhibiting ions. Herein, we provide an overview of the technologies that have been developed, including the general theory, design, and benefits/challenges associated with ion-selective electrode technologies (carrier-doped membranes, carbon-based varieties, enzyme inhibition electrodes). Notable variations of these electrodes will be highlighted, and a brief overview of associated electrochemical techniques will be given. Full article
(This article belongs to the Special Issue Amperometric Sensing)
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Figure 1

Figure 1
<p>General electrochemical cell set-up. Typically, a potentiostat is used as the ammeter, voltmeter, and function generator.</p> Full article ">Figure 2
<p>General design of a carrier-doped liquid-membrane electrode.</p> Full article ">Figure 3
<p>General enzyme features relevant to sensing technology.</p> Full article ">Figure 4
<p>(<b>A</b>) Potential vs. time signal for linear sweep; (<b>B</b>) Potential vs. time signal for cyclic voltammetry; (<b>C</b>) Potential vs. time signal for square wave voltammetry; (<b>D</b>) Potential vs. time signal for stripping voltammetry. Anodic stripping is shown in this case.</p> Full article ">
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