Bipolar transistor amplifier for transduction of electrochemical response to visual perception

• A simple electrochemical transducer for point-of-care applications with optical readout.
• Measuring device consists from only 4-electronic components and two sensing electrodes.
• Detection event is reported by the lighting up of the light emitting diode (LED).
• The signal is transduced/converted to visual perception using one bipolar transistor and one LED.
• The signal originates in the electrochemical cell connected to the voltage divider powered by 3 V battery.

A simple device for the transduction of an electrochemical signal to a visual readout suitable for point of care diagnostics has been designed. The transducer consists of an electrochemical cell and a 4-electronic components circuit, namely two resistors, one transistor and one light emitting diode (LED). The response from the electrochemical cell is amplified by the transistor providing output for the direct visual readout with the naked eye. Function of the device was verified in the experiments with hydrogen peroxide. Simple adjustment of the values of resistors provided tuneable sensitivity, positive threshold level and limit of detection as well. The biosensing abilities of the proposed system were tested on the analytical model using immobilised glucose oxidase. The principal benefits of the proposed platform include uniquely low construction costs and high simplicity. This approach is innovative in the transduction/conversion of the signal to visual perception and also in the signal generation – no potentiostat nor galvanostat are used compared to the majority of electrochemical measurements.

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