Response Of Glucose Sensor Research Articles

Numerical Modeling of Glucose Biosensor With pH-Based Electrochemical Field-Effect Transistor Device

In this article, we present a new model for glucose detection using an electrochemical field-effect transistor (ElecFET) with the MATLAB software. ElecFET is a device in which the basic element is a pH-sensitive chemical field-effect transistor (pH-ChemFET) designed with an integrated platinum microelectrode around the sensitive gate dielectric capable to trigger electrochemical reactions. A number of parameters, such as polarization time ( ${T}_{\text {pol}}$ ) and polarization voltage ( ${V}_{p}$ ), have been investigated, as well as the enzymatic unit number per volume ( ${N}_{\text {enz}}$ ), the Michaelis constant ( ${K}_{M}$ ), and the glucose concentration ( ${C}_{{0}}$ ). Each of the aforementioned parameters influences the glucose sensor response. Experimental data compared with our numerical model showed a reasonable fit.

Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution.

Cellulose nanofiber aqueous solution, which remained virtually transparent for more than one week, was prepared by using the clear upper layer of diluted cellulose nanofiber solution produced by wet jet milling. Glucose oxidase (GOx) was easily dissolved in this solution and GOx-immobilized electrode was easily fabricated by simple repetitious drops of GOx-cellulose solution on the surface of a platinum-iridium electrode. Glucose sensor properties of the obtained electrodes were examined in phosphate buffer solution of pH 7.4 at 40°C. The obtained electrode provided a glucose sensor response with significantly high response speed and good linear relationship between glucose concentration and response current. After an initial decrease of response sensitivity for a few days, relatively constant sensitivity was obtained for about 20 days. Nevertheless, the influence of electroactive compounds such as ascorbic acid, uric acid and acetoaminophen were not negletable.

Ultrasensitive non-enzymatic glucose sensing at near-neutral pH values via anodic stripping voltammetry using a glassy carbon electrode modified with Pt3Pd nanoparticles and reduced graphene oxide

We describe an anodic stripping voltammetric (ASV) method for glucose sensing that widely expands the typical amperometric i-t response of glucose sensors. The electrode is based on a working electrode consisting of a glassy carbon electrode modified with Pt-Pd nanoparticles (NPs; in an atomic ratio of 3:1) on a reduced graphene oxide (rGO) support. The material was prepared via the spontaneous redox reaction between rGO, PdCl4 2− and PtCl4 2− without any additional reductant or surfactant. Unlike known Pt-based sensors, the use of Pt3Pd NPs results in an ultrasensitive ASV approach for sensing glucose even at near-neutral pH values. If operated at a working voltage as low as 0.06 V (vs. SCE), the modified electrode can detect glucose in the 2 nM to 300 μM concentration range. The lowest detectable concentration is 2 nM which is much lower than the LODs obtained with other amperometric i-t type sensing approaches, most of which have LODs at a μM level. The sensor is not interfered by the presence of 0.1 M of NaCl.

In Vivo Glucose Measurement Using Fine Needle Type Amperometric Glucose Sensor

Fine needle type glucose sensors having outer membrane layers of heparin and urokinase were prepared. Glucose sensor properties were evaluated by in vitro measurement in phosphate buffer solution and horse serum, and in vivo measurement using the veins of rabbit. Glucose sensors were implanted using cannula and the blood glucose levels were influenced by the injection of glucose and insulin. Definite glucose was hardly observed at the days of implantation, while clear response was obtained after several days. This may due to the recovery from the damage of blood vessel received on the process of sensor implantation. Good correlation between in vitro blood glucose levels was obtained at especially low glucose level. Clear glucose sensor response was obtained even after 10 days of implantation. The formation on thrombus was not observed on the surface of sensor implanted for 10 days. This indicate that the glucose sensor with outer membrane of heparin and urokinase have excellent biocompatibility. Figure 1

Enzymatic Glucose Sensor Compensation for Variations in Ambient Oxygen Concentration.

Due to the increasing prevalence of diabetes, research toward painless glucose sensing continues. Oxygen sensitive phosphors with glucose oxidase (GOx) can be used to determine glucose levels indirectly by monitoring oxygen consumption. This is an attractive combination because of its speed and specificity. Packaging these molecules together in "smart materials" for implantation will enable non-invasive glucose monitoring. As glucose levels increase, oxygen levels decrease; consequently, the luminescence intensity and lifetime of the phosphor increase. Although the response of the sensor is dependent on glucose concentration, the ambient oxygen concentration also plays a key role. This could lead to inaccurate glucose readings and increase the risk of hyper- or hypoglycemia. To mitigate this risk, the dependence of hydrogel glucose sensor response on oxygen levels was investigated and compensation methods explored. Sensors were calibrated at different oxygen concentrations using a single generic logistic equation, such that trends in oxygen-dependence were determined as varying parameters in the equation. Each parameter was found to be a function of oxygen concentration, such that the correct glucose calibration equation can be calculated if the oxygen level is known. Accuracy of compensation will be determined by developing an overall calibration, using both glucose and oxygen sensors in parallel, correcting for oxygen fluctuations in real time by intentionally varying oxygen, and calculating the error in actual and predicted glucose levels. While this method was developed for compensation of enzymatic glucose sensors, in principle it can also be implemented with other kinds of sensors utilizing oxidases.

Ferrocenyl silicon-based dendrimers as mediators in amperometric biosensors

The application of ferrocene-containing dendrimers as mediators in amperometric biosensors is described. The steady-state amperometric response of carbon paste electrodes containing these dendritic relay systems and glucose oxidase is investigated as a function of the glucose concentration and the applied potential. The results show that these sensors respond rapidly to the addition of glucose. The dependence of the glucose sensor response on the size, the number of organometallic redox centers and the nature of the organosilicon dendritic framework is discussed.

A miniature Clark-type oxygen electrode using a polyelectrolyte and its application as a glucose sensor

A miniature Clark-type oxygen electrode was fabricated by anisotropically etching silicon. A two-gold-electrode configuration was used and a double-layered gas-permeable membrane was formed directly on the electrolyte, poly(vinyl-4-ethylpyridinium bromide) in the sensitive area. These materials improved the electrode's stability in long-term storage and sterilization tolerance to a practical level. The 90% response time averaged 80 s and residual current 10%, with a good linear calibration curve. The oxygen electrode was also used to make an integrated sensor for the simultaneous determination of glucose and oxygen. The glucose sensor's response time was 50–110 s, with good linearity in glucose concentrations between 56 μ m and 1.1 m m at 37°C, pH 7·0.

Immobilization of glucose oxidase on polymer membranes treated by low‐temperature plasma

Low-temperature plasma was employed for activation of polymer membranes as a carrier for enzyme immobilization. Glucose oxidase was immobilized on polypropylene (PP), polyvinylidene fluoride (PVDF), or polytetrafluoroethylene (PTFE) membrane surfaces treated by nitrogen or ammonia gas plasma using glutaraldehyde as a linking agent. Enzyme activity was evaluated by the response of glucose sensor composed of the immobilized enzyme membrane and a dissolved oxygen electrode. The sensor response was found to depend on the kind of carrier membrane and to become maximum at suitable conditions of plasma treatment.