Micropipette-based thermal sensor for biological applications

We present herein a novel technique for the fabrication of a glass micropipette thermal sensor utilizing inexpensive thermocouple materials and we are capable of measuring thermal fluctuation with accuracy of ±0.002 degree Celsius. We produced and tested various sensors in the sensing tip size, which ranges from 5 μm to 30 μm. The sensors comprise unleaded low melting point solder alloy (Sn) as a core metal inside a borosilicate glass pipette and thin film of nickel coated outside, creating a thermocouple junction at the tip. The sensor was calibrated by using a thermally insulated calibration chamber, the temperature of which can be controlled with precision of ± 0.1°C, and the thermoelectric power (Seebeck coefficient) of the sensor was recorded from 8.46 to 8.86 μV/°C. The sensor we have produced is cost-effective and reliable in application for thermal conductivity measurement of micro electro-mechanical systems (MEMS), and biological temperature sensing in micro level.