A Portable Chemical Detection System with Anti-body Biosensor for Impedance Based Monitoring of T2-mycotoxin Bioterrorism Agents
The work describes the development of a portable and autonomous biosensing label free platform for detection of biotoxin substances. The biosensor is realized as an on-chip package-free micro electrochemical cell consisting of a counter electrode (CE), a reference electrode (RE) and a working electrode (WE) patterned on a single silicon chip. To improve sensor sensitivity, the WE was implemented as a microelectrode array of 40 micron diameter gold disks with 400 micron centre-to-centre distance, which underwent corresponding surface modification for antibody immobilisation. The interfacial biosensor changes produced by T2-mycotoxin antigen-antibody reaction were sensed by means of Electrochemical Impedance Spectroscopy in a frequency range from 10 Hz to 100 kHz. The signal processing algorithm for mycotoxin quantification was based on analysis of biosensor impedance spectra and its equivalent electrical circuit. It is implemented in corresponding software at microcontroller and single-board computer level in such a manner that the results can be produced at point-of-need or in the decision center without user intervention. The instrumentation represented a mix signal measurement system which consisted of analog and digital parts. The analog part constituted a low noise, highly-sensitive hardware which implemented impedance measurements on the basis of a quadrature signal processing of the biosensor in response to a harmonic stimulation signal. The key unit of the digital part of the device was an Atmel microcontroller with inbuilt 12-bit ADC and external 16-bit DAC, which are responsible for device configuration, stimulation signal generation, biosensor signal digitalization, its initial signal processing and communication with the single-board computer. A calibration of the platform in the range of 0–250 ppm of T2 toxin concentrations confirmed that the system can provide successful detection of the toxin at the levels above 25 ppm.
KeywordsLabel-free biosensor T2-mycotoxin Immunosensor Surface modification Electrochemical Impedance Spectroscopy Portable instrumentation Equivalent circuit Signal processing
Financial support of this work by European Commission projects FP7-SEC-2011.3.4-2 “HANDHOLD: HANDHeld OLfactory Detector” and H2020-NMP-29-2015 “HISENTS: High level Integrated SEnsor for NanoToxicity Screening” is gratefully acknowledged.
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