Development of a distributed, fully automated, bidirectional telemetry system for amperometric microsensor and biosensor applications

A new bidirectional telemetry system for amperometric sensor applications has been developed. A fully automated peripheral unit (PU), constituted by a potentiostat, a two-channel I/V converter, a microcontroller unit (MCU) and a signal transmitter, was designed, constructed, and tested. A peripheral interface controller (PIC) MCU drives a digital-to-analog converter (DAC), which polarized the sensor, while the resulting anodic current is converted to a digital value by an analog-to-digital converter (ADC). The PIC firmware is developed in assembly and transferred to the MCU through a bootloader algorithm. The digital data are sent to a personal computer using a 4-byte packet protocol by means of a miniaturized 433 MHz frequency modulation (FM) transceiver with a linear range up to 200 m. The central unit (CU) is connected to a PC via Universal Serial Bus (USB). Custom developed software, implemented in Basic and C, allows the PC to control several PUs and record, plot and handle received data. The development and operation of the hardware and software are described. The system performance was evaluated using an automated dummy cell connected to the PU. The amperometric response of nitric oxide (NO), dopamine (DA) microsensors and a glucose biosensor was determined in vitro. This apparatus serves as a basic model to realize an in vivo bidirectional telemetry system built with standard components readily available at low cost.