Glass-based integrated capacitive sensors for detection of the neurotransmitter dopamine

The glass-based thin film transistor (TFT) process, as widely known for making liquid crystal displays, is utilised to make integrated capacitive sensors for dopamine detection. The interface capacitance change, after binding of dopamine and immobilised 4-carboxyphenylboronic acid, is detected through interdigitated microelectrodes and integrated sensing circuits. The associated impedance changes are analysed by an equivalent circuit model. Three designs with microelectrode capacitances of 28, 37 and 57 fF showed measured sensitivities of -3.9, -5.4 and -7.2 fF/mM, respectively. The minimum detectable capacitance changes were 12.7, 14.7 and 13.5 aF, equivalent to detectable dopamine concentrations of 3.2, 2.7 and 1.9 mu M, respectively.