A novel method for estimating triglycerides is reported. Porous silicon, prepared from p-type (100) crystalline silicon was thermally oxidized and used to immobilise lipase, an enzyme, which hydrolyses triglycerides resulting in the formation of fatty acids. This causes a change in the pH of the solution. Enzyme solution-oxidized porous silicon-crystalline silicon structure was used to detect changes in pH during the hydrolysis of tributyrin as a shift in the capacitance-voltage (C-V) characteristics. Detailed calibration of the sensor is included. © 2001 Elsevier Science B.V.

Anju Chadha

Department Of Biotechnology

Enakshi Bhattacharya

Department of Electrical Engineering

R. Ravi Kumar Reddy

Biosensors

Calibration

enzyme immobilization

Fatty acids

Hydrolysis

Thermooxidation

Lipase

Porous silicon

fatty acid

Silicon

TRIACYLGLYCEROL LIPASE

TRIBUTYRIN

article

biosensor

Electric potential

enzyme activity

oxidation

potentiometry

technique

Biosensing Techniques

Triglycerides

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Porous silicon based potentiometric triglyceride biosensor.

Biosensors and Bioelectronics

This paper reports on the design and fabrication of electrolyte insulator semiconductor capacitor (EISCAP) devices to detect triglycerides in the form of microreactors fabricated by bulk micromachining of silicon. We have developed a complete triglyceride biochip wherein the enzyme for hydrolysis and the counter electrode for signal transduction are integrated with a miniaturised EISCAP sensor. A compact readout system that measures the triglyceride concentration in blood serum under test has been developed and is implemented in a Programmable System on Chip (PSoC®). The miniaturised EISCAP devices are tested using blood serum samples to estimate the triglyceride concentration within the clinical range of 50 to 150 mg dL-1 and the time taken by the readout system to calibrate the sensor and to measure the triglyceride is less than 5 minutes. © The Royal Society of Chemistry 2014.

Fulltext

Analytical Methods

Miniaturised silicon biosensors for the detection of triglyceride in blood serum

A modified electrolyte-insulator-semiconductor-capacitor (EISCAP) developed in-house was used for the determination of triglycerides and urea in blood, in addition to urea in milk. The sensitivity of the sensor was 55 ± 0.5 mV per unit change of pH. The EISCAP was optimized to operate at 25 °C in 0.25 mM phosphate buffer (pH 6), 1 M KCl and 1 mg lipase for triglycerides and in 1 mM Tris-HCl buffer (pH 7.4), 0.5 M KCl and 0.5 U urease for urea. Comparisons of the results obtained from the developed biosensor and clinical records gave correlation coefficients of 0.979 and 0.974 for blood triglycerides and blood urea respectively. Similarly, estimation of milk urea determined using the sensor in comparison with the spectrophotometric method gave a correlation coefficient of 0.992. The sensor gave reproducible and reliable results up to six months. © 2011 Elsevier B.V. All rights reserved.

Sensors and Actuators, B: Chemical

Potentiometric estimation of blood analytes - Triglycerides and urea: Comparison with clinical data and estimation of urea in milk using an electrolyte-insulator-semiconductor-capacitor (EISCAP)

In this paper we discuss the fabrication and characterization of miniaturized triglyceride biosensors on crystalline silicon and porous silicon (PS) substrates. The sensors are miniaturized Electrolyte Insulator Semiconductor Capacitors (mini-EISCAPs), which primarily sense the pH variation of the electrolyte used. The lipase enzyme, which catalyses the hydrolysis of triglycerides, was immobilized on the sensor surface. Triglyceride solutions introduced into the enzyme immobilized sensor produced butyric acid which causes the change in pH of the electrolyte. Miniaturized EISCAP sensors were fabricated using bulk micromachining technique and have silicon nitride as the pH sensitive dielectric layer. The sensors are cubical pits of dimensions 1,500 μm × 1,500 μm × 100 μm which can hold an electrolyte volume of 0.1 μl. The pH changes in the solution can be sensed through the EISCAP sensors by monitoring the flatband voltage shift in the Capacitance-Voltage (C-V) characteristics taken during the course of the reaction. The reaction rate is found to be quite high in the miniature cells when compared to the sensors of bigger dimensions. © 2008 Springer Science+Business Media, LLC.

Journal of Materials Science: Materials in Medicine

Miniaturization of EISCAP sensor for triglyceride detection

Sensitive biosensors for detection of triglyceride concentration are important. In this paper we report on two types of silicon based triglyceride sensors: an electrolyte-insulator-semiconductor capacitor (EISCAP) which is a potentiometric device and a polysilicon microcantilever. The detection principle for both sensors is based on the enzymatic hydrolysis of triglyceride though the sensing mechanisms are different: electronic for the EISCAP and mechanical for the microcantilever. The characteristics and performances of the two sensors are critically compared. The EISCAP sensor necessitates the presence of a buffer for stable measurements which limits the sensitivity of the sensor at low concentrations of the bioanalyte to 1 mM. The cantilever sensor works without a buffer which improves the lower level of sensitivity to 10 μm. Both sensors are found to give reproducible and reliable results. © 2008 Elsevier B.V. All rights reserved.

Comparison of a potentiometric and a micromechanical triglyceride biosensor

A novel composite porous silicon/polysilicon microcantilever for biosensing applications with enhanced sensitivity is reported. It is fabricated by surface micromachining of polysilicon cantilevers followed by the formation of the surface porous layer after release by Reaction Induced Vapor Phase Stain Etch. The microcantilevers with porous surface layer are characterized by their morphology that exhibits a dual macro and nanostructure for very effective immobilization of biomolecules. The current work focuses on the fabrication of composite porous silicon/polysilicon microcantilevers, characterization of their morphology and resonance frequency, as well as demonstration of improved immobilization of enzyme resulting in enhanced sensing of triglycerides. © 2009 IEEE.

IEEE Sensors Journal

MEMS composite porous silicon/polysilicon cantilever sensor for enhanced triglycerides biosensing

Molecular Physics

ANNOUNCEMENT

Sensors and Actuators A: Physical

The effect of additives on the adsorption properties of porous silicon

1997 IEEE Hong Kong Proceedings Electron Devices Meeting HKEDM-97

1997 IEEE Hong Kong Proceedings Electron Devices Meeting

Japanese Journal of Applied Physics

Gas Identification by a Single Gas Sensor using Porous Silicon as the Sensitive Material

Porous Silicon Science and Technology

Porous silicon based potentiometric triglyceride biosensor

Journal	Biosensors and Bioelectronics
ISSN	09565663
Open Access	No