Enokitake Mushroom-like Standing Gold Nanowires toward Wearable Noninvasive Bimodal Glucose and Strain Sensing (original) (raw)
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A new approach to glucose sensing at gold electrodes
Electrochemistry Communications, 2010
An oxidative peak in the cathodic scan is observed in the cyclic voltammetry of glucose at gold electrodes, its peak current density being proportional to glucose concentration in a wide potential range. The application of this phenomenon in blood glucose sensing has been hindered by the presence of inhibitors: the most problematic are chlorides due to their high concentration and difficult separation from glucose. In the present paper we propose a solution to this problem involving a three electrode, four step pulsed electrochemical detection technique.
Glucose Level Estimation Based on Invasive Electrochemical, and Non-Invasive Optical Sensing Methods
2018
The purpose of this research is to design and fabricate sensors for glucose detection using inexpensive approaches. My first research approach is the fabrication of an amperometric electrochemical glucose sensor, by exploiting the optical properties of semiconductors and structural properties of nanostructures, to enhance the sensor sensitivity and response time. Enzymatic electrochemical sensors are fabricated using two different mechanisms: (1) the lowtemperature hydrothermal synthesis of zinc oxide nanorods, and (2) the rapid metal-assisted chemical etching of silicon (Si) to synthesize Si nanowires. The concept of gold nano-electrode ensembles is then employed to the sensors in order to boost the current sensitivities by enhancing the rate of electron transfer during the electrochemical reaction. High crystallinity and good alignment of the nanostructures lead to increase in the electrode surface area, thereby leading to higher current sensitivities compared to other published w...
Nanogap-based enzymatic-free electrochemical detection of glucose
2013 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2013
Although non-enzymatic glucose sensors have demonstrated better stability and reproducibility with respect to enzymatic ones, so far they have been inappropriate for most applications, since they require alkaline conditions to achieve the necessary sensitivity. In this work, we propose a gold nanogap-based non-enzymatic sensor to localize the generation of alkaline conditions inside the gap, thus preserving the overall pH in the media during glucose detection. The working principle is based on an electrochemical bi-potentiostatic measurement, where an alkaline aqueous condition is locally generated at one side of nanogap, while glucose detection is performed at the counterpart. To this purpose, a nanogap array platform was fabricated by means of standard lithography and controlled electromigration. Mono-potentiostatic electrochemical detection of ascorbic acid was successfully performed to preliminary test the platform prior to measuring glucose in bi-potentiostatic mode. Cyclic voltammetries reveal that two oxidation peaks are sensitive to glucose concentration, making nanogap glucose detection possible in principle. This promising proof of concept could be innovative in bio-applications with implantable devices or direct monitoring of cell culture, where neutral pH in contact with living tissue is required. Further geometrical improvements of the system to increase the durability of the sensor are currently still in progress, and are briefly discussed in the final part of the paper. I.
Current advancements and prospects of enzymatic and non-enzymatic electrochemical glucose sensors
International Journal of Biological Macromolecules, 2023
This review discusses the most current developments and future perspectives in enzymatic and non-enzymatic glucose sensors, which have notably evolved over the preceding quadrennial period. Furthermore, a thorough exploration encompassed the sensor's intricate fabrication processes, the diverse range of materials employed, the underlying principles of detection, and an in-depth assessment of the sensors' efficacy in detecting glucose levels within essential bodily fluids such as human blood serums, urine, saliva, and interstitial fluids. It is worth noting that the accurate quantification of glucose concentrations within human blood has been effectively achieved by utilizing classical enzymatic sensors harmoniously integrated with optical and electrochemical transduction mechanisms. Monitoring glucose levels in various mediums has attracted exceptional attention from industrial to academic researchers for diabetes management, food quality control, clinical medicine, and bioprocess inspection. There has been an enormous demand for the creation of novel glucose sensors over the past ten years. Research has primarily concentrated on succeeding biocompatible and enhanced sensing abilities related to the present technologies, offering innovative avenues for more effective glucose sensors. Recent developments in wearable optical and electrochemical sensors with low cost, high stability, point-of-care testing, and online tracking of glucose concentration levels in biological fluids can aid in managing and controlling diabetes globally. New nanomaterials and biomolecules that can be used in electrochemical sensor systems to identify glucose concentration levels are developed thanks to advances in nanoscience and nanotechnology. Both enzymatic and non-enzymatic glucose electrochemical sensors have garnered much interest recently and have made significant strides in detecting glucose levels. In this review, we summarise several categories of non-enzymatic glucose sensor materials, including composites, non-precious transition metals and their metal oxides, hydroxides, precious metals and their alloys, carbon-based materials, conducting polymers, metal-organic framework (MOF)-based electrocatalysts, and wearable device-based glucose sensors deeply.
Journal of Materials Chemistry B, 2021
In this study, a novel non-enzymatic glucose biosensor based on a simple photolithographic process is proposed. To fabricate the sensor, photoresist AZ-1518 was spin-coated onto a reclaimed silicon wafer, and then, a mask with a hexagonal close-packed circle array was employed for exposure and development to generate a hexagonal close-packed column array of AZ-1518. The diameter of each circle was set as 3 m. Subsequently, a thermal melting process was employed to convert each photoresist column into a photoresist hemisphere. A gold thin film was then sputtered onto the hemisphere array of AZ-1518 to form the sensing electrode. Finally, gold nanoparticles were deposited onto the gold thin film using a self-assembly monolayer method to enhance the sensing area. Measurements showed a 10.2fold enhancement of the sensing area in comparison with a plain gold electrode. Actual detection of glucose demonstrated that the proposed non-enzymatic glucose biosensor can operate in a linear range of 55.6 M-13.89 mM. It had a sensitivity of 749.2 A mM −1 cm −2 and a detection limit of 9 M. The novel glucose biosensor proposed here has several advantages such as being enzyme free, simple to fabricate, low cost, and easy to preserve on a long-term basis. Thus, it can feasibly be used for future clinical applications.
Review on Recent Developments in Non-Enzymatic Electrochemical Glucose Sensors
Currently, there is a great demand for the development and improvement of glucose sensors for significance in biomedical applications. Special attention is given to the discussion on some problems and bottlenecks in areas of non-enzymatic and enzymatic (glucose oxidase based) amperometric glucose sensing. The evolution of first to third generation electrochemical glucose sensors reflects a simplification and enhancement of the transduction pathway. In order to meet special needs, a move towards non-enzymatic glucose sensors has begun. These new sensors have garnered significant interest due to their capacity to achieve continuous glucose monitoring, their high stability compared to traditional glucose sensors, and the ease of their fabrication. Research has been extensively geared towards the preparation of these non-enzymatic glucose sensors from novel materials, often with nanostructures, which possess ideal properties for electrochemical sensor applications. In the recent report of nanotechnology research, unique nanostructures and techniques have been used to bring innovative developments to current glucose sensors. However, there are still a lot of challenges ahead with respect to utilization in the human body, before the commercialization of these techniques is possible. Most glucose sensors based on novel materials have been limited due to their poor biocompatibility, high cost, and very time intensive preparation processes.This review discussed the selective reports on the fabrication and recent developments of enzymatic and non-enzymatic glucose sensors and their future challenges during the period spanning mid of 2006 to beginning of 2016.
Sensors (Basel, Switzerland), 2009
In this report, alkanethiol self assembled monolayers (SAM) with two different chain lengths were used to immobilize the functionalizing enzyme (glucose oxidase) onto gold nanopillar modified electrodes and the electrochemical processes of these functionalized electrodes in glucose detection were investigated. First, the formation of these SAMs on the nanopillar modified electrodes was characterized by the cyclic voltammetry and electrochemical impedance spectroscopy techniques, and then the detection sensitivity of these functionalized electrodes to glucose was evaluated by the amperometry technique. Results showed that the SAM of alkanethiols with a longer chain length resulted in a higher degree of surface coverage with less defect and a higher electron transfer resistance, whereas the SAM of alkanethiols with a shorter chain length gave rise to a higher detection sensitivity to glucose. This study sheds some new insight into how to enhance the sensing performance of nanopillar m...
Sensitivity enhancement in an in-vitro glucose sensor using gold nanoelectrode ensembles
Enzymatic electrochemical sensor for glucose detection is fabricated based on hydrothermally grown zinc oxide (ZnO) nanorods. The conception of gold (Au) nanoelectrode ensembles (NEEs) is applied to enhance the sensitivity of the electrochemical sensor under investigation. The characterization of as-synthesized ZnO nanorods on Au and indium tin oxide substrates is performed using X-ray diffraction, scanning electron microscopy, and micro- Raman spectroscopy. The current sensitivity of sensors with and without Au NEEs are computed using the cyclic voltammetry and amperometric tests executed for the glucose level ranging from 0.01 to 11.00 mM/L. Current sensitivity of 7.5 μA/mM for a linear range of glucose concentration from 0.01 to 6.5 mM is testified. Response time of 1 s and a low limit of detection of 0.065 mM is reported for the sensor based on Au NEEs. The need of ZnO nanorods in the sensor working electrode, to immobilize enzyme glucose oxidase is justified. The presence of Au NEEs boost the sensor current sensitivity by enhancing the rate of electron transfer during the electrochemical reaction.
Flexible Enzymatic Glucose Electrochemical Sensor Based on Polystyrene-Gold Electrodes
Micromachines
Metabolic disorders such as the highly prevalent disease diabetes require constant monitoring. The health status of patients is linked to glucose levels in blood, which are typically measured invasively, but can also be correlated to other body fluids such as sweat. Aiming at a reliable glucose biosensor, an enzymatic sensing layer was fabricated on flexible polystyrene foil, for which a versatile nanoimprinting process for microfluidics was presented. For the sensing layer, a gold electrode was modified with a cysteine layer and glutaraldehyde cross-linker for enzyme conformal immobilization. Chronoamperometric measurements were conducted in PBS buffered glucose solution at two potentials (0.65 V and 0.7 V) and demonstrated a linear range between 0.025 mM to 2mM and an operational range of 0.025 mM to 25 mM. The sensitivity was calculated as 1.76µA/mM/cm2 and the limit of detection (LOD) was calculated as 0.055 mM at 0.7 V. An apparent Michaelis–Menten constant of 3.34 mM (0.7 V) a...