3 February 2017 The characterisation and design improvement of a paper-based E.coli impedimetric sensor
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Proceedings Volume 10036, Fourth Conference on Sensors, MEMS, and Electro-Optic Systems; 100360L (2017) https://doi.org/10.1117/12.2245754
Event: Fourth Conference on Sensors, MEMS and Electro-Optic Systems, 2016, Skukuza, Kruger National Park, South Africa
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.
© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
P. Bezuidenhout, S. Kumar, M. Wiederoder, J. Schoeman, K. Land, T-H. Joubert, "The characterisation and design improvement of a paper-based E.coli impedimetric sensor", Proc. SPIE 10036, Fourth Conference on Sensors, MEMS, and Electro-Optic Systems, 100360L (3 February 2017); doi: 10.1117/12.2245754; https://doi.org/10.1117/12.2245754

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