A Simple Low Power Electronic Readout for Rapid Bacteria Detection With Impedance Biosensor

A low power, low cost, and simple electronic readout system has been developed for rapid bacteria detection with impedance biosensor. Such an interface will enable the label free and rapid impedance biosensors convenient for field use. From the experimental reading of the macroporous silicon based impedance biosensor, it has been observed that the sensitivity variation is not affected significantly by a 10% fluctuation in frequency but the amplitude of the signal has to be maintained within 30 mV. Thus, the electronic interface is designed to generate automatically sinusoidal waveforms of discrete values in the wide range 100-100 kHz with low power and moderate cost budget by interfacing a high-Q band pass filter with a rectangular waveform of maximum frequency 15 kHz obtained from an ordinary 16 MHz ATMEGA8 microcontroller. This scheme enables the control of voltage within 30 mV amplitude by tuning the duty cycle of the rectangular waveform. The power consumption of the sine wave generator is maintained within 30 mW. User selectable zero offset features and calibration facilities have also been incorporated. The impedance biosensor system has been tested with E.coli and S.Typhimurium spiked blood samples and the results are satisfactory.