Papers by Vinu Mohan A. M.
Sensors and Actuators B: Chemical
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Advanced Nanomaterials for Point of Care Diagnosis and Therapy, 2022
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Nano Energy, 2019
Abstract While the textile based stretchable supercapacitors have been demonstrated as efficient ... more Abstract While the textile based stretchable supercapacitors have been demonstrated as efficient charge storage devices, challenges in developing self powered wearable devices still exist. The present work describes a screen printed flexible and stretchable supercapacitor that can act as an energy buffering element for powering wearable fitness monitoring devices. The supercapacitor possesses interdigitated shaped intrinsically stretchable electrodes with free-standing serpentine interconnects. The symmetric supercapacitor relies on carbon nanotube and poly(aniline) as active materials and polyurethane as a stretch enduring binder. Such in-plane supercapacitors are realized by initially printing on a paper substrate, pre-coated with a water soluble layer, and then transferred onto a pre-strained elastomeric substrate. The supercapacitor showed excellent mechanical resiliency even though subjected to intense mechanical deformations. The electrode possessed highest areal capacitance of 167 mF/cm2 at a current density of 0.4 mA/cm2 and showed appreciable areal energy and power density of 14.9 μWh/cm2 and 0.29 mW/cm2, respectively. The supercapacitor showed conformal integration with the stretchable sweat band and which (3 devices, in series) can independently power a red light emitting diode. In combination with a flexible solar cell and a custom-made low power booster, the supercapacitor can continuously powers the wearable pulse rate sensor even in the presence of poor sunlight intensity.
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TrAC Trends in Analytical Chemistry, 2020
Abstract The majority of existing medical diagnosis depends on the blood analysis in centralized ... more Abstract The majority of existing medical diagnosis depends on the blood analysis in centralized sophisticated laboratories having bulky, complex, and time-consuming clinical instruments. Blood test involves invasive sample collection followed by plasma separation via centrifugation, and chemical analyses. This may prevent persons in need of urgent medical diagnosis and prompt medical attention. Wearable biosensor offers non-invasive monitoring of physiologically relevant biomarkers from biofluids and continuous tracking of real-time health status. Recent advances are much focused on electrochemical monitoring of various biomarkers from sweat samples. Such skin-interfaced sweat sensors require flexibility, stretchability and self-healing ability to match with the mechanical properties of the epidermis. The multiplexed sweat analysis coupled with wireless signal transduction provides vital information about health and fitness level of the wearer. This review focuses on the challenges, perspectives, recent advances and the technological aspects in the progress of wearable electrochemical sweat sensors.
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ACS Sensors
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ACS Applied Materials & Interfaces
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Materials
Next-generation wearable technology needs portable flexible energy storage, conversion, and biose... more Next-generation wearable technology needs portable flexible energy storage, conversion, and biosensor devices that can be worn on soft and curved surfaces. The conformal integration of these devices requires the use of soft, flexible, light materials, and substrates with similar mechanical properties as well as high performances. In this review, we have collected and discussed the remarkable research contributions of recent years, focusing the attention on the development and arrangement of soft and flexible materials (electrodes, electrolytes, substrates) that allowed traditional power sources and sensors to become viable and compatible with wearable electronics, preserving or improving their conventional performances.
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Sensors
Aptamers are synthetic bio-receptors of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) ori... more Aptamers are synthetic bio-receptors of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) origin selected by the systematic evolution of ligands (SELEX) process that bind a broad range of target analytes with high affinity and specificity. So far, electrochemical biosensors have come up as a simple and sensitive method to utilize aptamers as a bio-recognition element. Numerous aptamer based sensors have been developed for clinical diagnostics, food, and environmental monitoring and several other applications are under development. Aptasensors are capable of extending the limits of current analytical techniques in clinical diagnostics, food, and environmental sample analysis. However, the potential applications of aptamer based electrochemical biosensors are unlimited; current applications are observed in the areas of food toxins, clinical biomarkers, and pesticide detection. This review attempts to enumerate the most representative examples of research progress in aptamer based ...
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Biosensors & bioelectronics, Jan 15, 2018
This article demonstrates a new smartphone-based reusable glucose meter. The glucose meter includ... more This article demonstrates a new smartphone-based reusable glucose meter. The glucose meter includes a custom-built smartphone case that houses a permanent bare sensor strip, a stylus that is loaded with enzyme-carbon composite pellets, and sensor instrumentation circuits. A custom-designed Android-based software application was developed to enable easy and clear display of measured glucose concentration. A typical test involves the user loading the software, using the stylus to dispense an enzymatic pellet on top of the bare sensor strip affixed to the case, and then introducing the sample. The electronic module then acquires and wirelessly transmits the data to the application software to be displayed on the screen. The deployed pellet is then discarded to regain the fresh bare sensor surface. Such a unique working principle allows the system to overcome challenges faced by previously reported reusable sensors, such as enzyme degradation, leaching, and hysteresis effects. Studies r...
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Thin Solid Films
ABSTRACT A thin film of hybrid cobalt–manganese hexacyanoferrate (CoMnHCF), a redox mediator was ... more ABSTRACT A thin film of hybrid cobalt–manganese hexacyanoferrate (CoMnHCF), a redox mediator was electrodeposited on a glassy carbon (GC) electrode and was employed as an amperometric sensor towards l-Tryptophan (l-Trp). The hybrid film was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction technique (XRD), scanning electron microscope–energy dispersive X-ray spectroscopy (SEM–EDAX), and electrochemical techniques. The atomic absorption spectroscopic analysis provided the stoichiometry of the hybrid film to be K1.74-y Coy Mn0.78 [Fe(CN)6], y ≤ 0.68. The electrochemical impedance study revealed the excellent charge transfer properties of GC/CoMnHCF electrode. The voltammetric investigations demonstrated exceptional electrocatalytic properties of the hybrid film modified electrode when compared to that of bare GC, GC/CoHCF and GC/MnHCF electrodes, towards the l-Trp oxidation. The kinetic parameters such as electron transfer coefficient, the electron transfer rate constant, the diffusion coefficient and the catalytic rate constant for the electrooxidation process of l-Trp were investigated. The amperometric detection of l-Trp employing GC/CoMnHCF electrode possessed a good sensitivity of 10 × 10− 2 A M− 1 cm− 2 in a wide range of detection (2–200 μM) at a reduced overpotential of 680 mV. In addition, the proposed amperometric method was applied to the detection of l-Trp in commercial milk samples with reproducible results.
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Energy Environ. Sci.
A soft, stretchable wearable biofuel cell producing ∼1 mW power from sweat is presented.
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Advanced Materials Technologies
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The Analyst, Jan 21, 2017
A microneedle electrochemical biosensor for the minimally invasive detection of organophosphate (... more A microneedle electrochemical biosensor for the minimally invasive detection of organophosphate (OP) chemical agents is described. The new sensor relies on the coupling of the effective biocatalytic action of organophosphorus hydrolase (OPH) with a hollow-microneedle modified carbon-paste array electrode transducer, and involves rapid square-wave voltammetric (SWV) measurements of the p-nitrophenol product of the OPH enzymatic reaction in the presence of the OP substrate. The scanning-potential SWV transduction mode offers an additional dimension of selectivity compared to common fixed-potential OPH-amperometric biosensors. The microneedle device offers a highly linear response for methyl paraoxon (MPOx) over the range of 20-180 μM, high selectivity in the presence of excess co-existing ascorbic acid and uric acid and a high stability sensor upon exposure to the interstitial fluid (ISF). The OPH microneedle sensor was successfully tested ex vivo using mice skin samples exposed to MP...
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Biosensors and Bioelectronics, 2017
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Science Advances, 2016
The present work demonstrates the synthesis and application of permanent magnetic Nd2Fe14B microp... more The present work demonstrates the synthesis and application of permanent magnetic Nd2Fe14B microparticle (NMP)–loaded graphitic inks for realizing rapidly self-healing inexpensive printed electrochemical devices. The incorporation of NMPs into the printable ink imparts impressive self-healing ability to the printed conducting trace, with rapid (~50 ms) recovery of repeated large (3 mm) damages at the same or different locations without any user intervention or external trigger. The permanent and surrounding-insensitive magnetic properties of the NMPs thus result in long-lasting ability to repair extreme levels of damage, independent of ambient conditions. This remarkable self-healing capability has not been reported for existing man-made self-healing systems and offers distinct advantages over common capsule and intrinsically self-healing systems. The printed system has been characterized by leveraging crystallographic, magnetic hysteresis, microscopic imaging, electrical conductivi...
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Materials science & engineering. C, Materials for biological applications, 2016
Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder... more Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder medications and is toxic at higher concentration. The development of a molecularly imprinted polymer based theophylline electrochemical sensor on glassy carbon electrode by the electropolymerization of 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid is being discussed in this work. The MIP modification enhances the theophylline recognition ability and the electron transfer kinetics of the bare electrode. The parameters, controlling the performance of the imprinted polymer based sensor, like number of electropolymerization cycles, composition of the pre-polymerization mixture, pH and immersion time were investigated and optimized. The interaction energy and the most stable conformation of the template-monomer complex in the pre-polymerization mixture were determined computationally using ab initio calculations based on density functional theory. The amperometric measurements showed that...
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Nature Communications, 2016
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Advanced Electronic Materials, 2015
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Papers by Vinu Mohan A. M.