Thermal control system based on thin film heaters and amorphous silicon diodes

In this paper we present a system able to perform thermal treatments on lab-on-chip devices fabricated on glass substrates. The system includes a thin film resistor acting as heater and thin film hydrogenated amorphous silicon diodes acting as temperature sensors. An electronic system controls the lab-on-chip temperature through a Proportional-Integral Derivative algorithm. In particular, an electronic board infers the system temperature measuring the voltage across the amorphous silicon diodes and drives the heater to achieve the set-point temperature. Taking into account the 16-bit ADC resolution and the sensors sensitivity, which is around 3.6 mV/degrees C, we estimate that our system is able to detect temperature variation as low as 3.5.10(-3) degrees C. Furthermore, the experimental results show that the system is able to stabilize the system temperature with a precision better than 0.1 degrees C.