Thermo-sensitive microgels as in-situ sensor for temperature measurement in optoelectronic tweezers

We report on the application of thermo-sensitive microgels as in situ temperature sensor for phototransistor-based optoelectronic tweezers (Ph-OET) device. The thermo-sensitive microgels are cross-linked polymeric particles that swell or shrink reversibly in response to changes in the surrounding temperature. The technique has an accuracy of 0.054°C and a spatial resolution of 25 ¿m. Temperature rise in Ph-OET is measured under various operating conditions, and the maximum temperature increase is measured at 2.6°C. The results show cell damage can be prevented with adequate heat sink. When physiological temperature is required, the applied bias should be kept low (10 V_pp), or smaller optical patterns should be used. The technique demonstrated here can be extended to other microfluidic devices.