Electrodes for Temperature Sensing or Heating
Fluids can be heated using an integrated
resistive heating element made from platinum. Locally high temperatures of
several hundred degrees Celsius can be created within a couple of seconds using
safe to use low voltages. For a homogeneous temperature across a large area of
the chip the use of a transparent layer of electrically conductive ITO is
usually advisable.
The integrated resistors can also be used to measure temperature, but it should be noted that there is some variation in the room temperature resistance from chip to chip and the temperature coefficient is not necessarily the same as for industrial Pt100 sensors. Sensors should therefore be individually calibrated.
The combination of electrical heaters and temperature sensors on a chip provides a convenient means to warm fluids inside microchannels to the desired temperature.