A low power sensor read-out circuit has been implemented in 0.35νm CMOS technology that consumes only 400νW of power and occupies anarea of 0.66mm2. The circuit is capable of converting the current signal from any generic biosensor into an amplitude shift keying (ASK) signal. The on-chip potentiostat biases the chemical sensor electrodes to create the sensor current which is then integrated and buffered to generate a square wave with a frequency proportional to the sensor current level. A programmable frequency divider is incorporated to fix the ASK envelope frequency to be inbetween 20Hz and 20kHz, which is within the audible range of human hearing. The entire transmitter block operates with a supply voltage as low as 1.5V, and it can be easily powered up by an external RF source. Test results emulate the simulation results with good agreement and corroborate the efficacy of the designed system. © IOP Publishing Ltd.