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Proceedings Paper

The characterisation and design improvement of a paper-based E.coli impedimetric sensor
Author(s): P. Bezuidenhout; S. Kumar; M. Wiederoder; J. Schoeman; K. Land; T-H. Joubert
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Paper Abstract

This paper describes the development and optimisation of a paper-based E. coli impedimetric biosensor for water quality monitoring. Impedimetric biosensing is advantageous because it is a highly sensitive, label-free, real-time method for the detection of biological species. An impedimetric biosensor measures the change in impedance caused by specific capture of a target on the sensor surface. Each biosensor consists of a pair of photo paper-based inkjet printed electrodes. An impedance analyser was used to measure the impedance at frequencies ranging from 1 kHz to 1 MHz at 1V.

The parameters that were investigated to achieve enhanced sensor performance were buffer type, antibody attachment method, measurement frequency, electrode layout, and conductive material. A 0.04M PBS (phosphate buffered saline) solution achieves better results compared to a less conductive 0.04M PB (potassium phosphate dibasic) solution. The direct adsorption of anti-E. coli antibodies onto the sensor surface yielded better results than attaching the sensor to a lateral flow test. The resistive component had a greater impact on the detected impedance, therefore an optimal frequency of 1 MHz was identified. Geometrical electrode designs that maximise the resistive change between the electrodes were utilised. Both lower cost silver and bio-compatible gold ink were validated as electrode materials. The impedance change generated by the selective capture of E. coli K-12, ranging in concentration from 103 to 107 colony forming units per millilitre (cfu/ml), showed a detection limit of 105 cfu/ml.

Paper Details

Date Published: 3 February 2017
PDF: 6 pages
Proc. SPIE 10036, Fourth Conference on Sensors, MEMS, and Electro-Optic Systems, 100360L (3 February 2017); doi: 10.1117/12.2245754
Show Author Affiliations
P. Bezuidenhout, Council for Scientific and Industrial Research (South Africa)
S. Kumar, Council for Scientific and Industrial Research (South Africa)
M. Wiederoder, Univ. of Maryland (United States)
J. Schoeman, Univ. of Pretoria (South Africa)
K. Land, Council for Scientific and Industrial Research (South Africa)
T-H. Joubert, Univ. of Pretoria (South Africa)

Published in SPIE Proceedings Vol. 10036:
Fourth Conference on Sensors, MEMS, and Electro-Optic Systems
Monuko du Plessis, Editor(s)

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