Portable surface stress biosensor test system based on ZigBee technology for health care

The paper presents a portable surface stress biosensor test system based on ZigBee technology for health care, which consists of a biosensor chip and an electronic test platform. The biosensor chip is a micro-scale and label-free polydimethylsiloxane micromembrane capacitive surface stress sensor. This chip consists of two micromembranes, in which one acts as the active unit and the other as reference. The signal difference of active and reference is acquired with the aid of capacitive detection circuit, which has high signal-to-noise ratio and speedy electrical readout. The electronic test platform is designed based on ZigBee technology to realize the accurate detection of small capacitance and the wireless signal transmission. The capacitive resolution of the system is 0.1 fF (femtofarad). The capacitance measured by the system is diminished and exaggerated with the increase and decrease of ethanol volume, which is corresponding to the capacitive formula. The haemoglobin test results from the system are consistent with the theoretical analysis and the test results from Agilent B1500A, which demonstrates that the system can be considered as a measurer of haemoglobin for clinical applications. The experiments also illustrate that the biosensor test system has good stability and multiplicity.