A novel, enzymatic, porous silicon (PS) based potentiometric method for estimating triglycerides is reported. Lipase, an enzyme, which hydrolyses triglycerides was immobilised on PS which was prepared from p-type (1 0 0) crystalline silicon and was thermally oxidized. On hydrolysis the triglycerides result in the formation of fatty acids which causes a change in the pH of the solution. Enzyme solution-oxidized PS-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. Optimisation of the conditions for the enzymatic reaction and calibration of the sensor are included. © 2002 Elsevier Science B.V. All rights reserved.

Enakshi Bhattacharya

Department of Electrical Engineering

Anju Chadha

Department Of Biotechnology

Indranil Basu

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

Estimation of triglycerides by a porous silicon based potentiometric biosensor

Current Applied Physics

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)

We report the fabrication of potentiometric electrolyteinsulator capacitor (EISCAP) biosensors based on silicon and porous silicon (PS) substrates with oxide and stacked oxidenitride dielectrics. These biosensors have been calibrated for the detection and estimation of bioanalytes like tributyrin and urea, based on enzymatic reactions and have a linear detection range from 0.1 mM to 20 mM of the bioanalyte concentration. These improved sensitivity EISCAP sensors were used for the estimation of the total acid content in rancid butter, estimation of enzyme (Lipase) activity and to estimate total triglyceride levels in blood serum. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physica Status Solidi (A) Applications and Materials Science

Novel applications of silicon and porous silicon based EISCAP biosensors

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

A novel composite porous silicon/polysilicon microcantilever for biosensing applications with enhanced sensitivity is reported. It is fabricated by surface mi cromachining 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 demonstration of improved immobilization of enzymes resulting in enhanced sensing of triglycerides. © 2008 IEEE.

Proceedings of IEEE Sensors

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.

Journal	Current Applied Physics
ISSN	15671739
Open Access	No