Abstract
We have developed a resonant thermal sensor system for biological samples. The measurement principle relies on the resonant frequency shift of the resonant thermal sensor due to the temperature change. Brown fat cells, which are frequently used for metabolism researches, attract our interests to solve obesity, metabolic syndrome, and so on. To measure its thermal characteristics in single cell level, a heat loss to surrounding environments and a vibration damping should be solved when resonant thermal sensors are immersed in water. To solve these problems and realize highly sensitive thermal measurements, a resonant thermal sensor was partly placed in vacuum, and another end was in microchannel as a sample stage in a microfluidic chip. They were connected physically and thermally by a heat guide. The heat from the cell is conducted to the sensor via the heat guide, and measured. A fabricated device was evaluated by using laser Doppler vibrometer. The thermal resolution of the device was 5.2 pJ. The single brown fat cell was set on the sample stage, and generated heats were measured with and without stimulation. With the stimulation, pulsed heats were observed, which have not observed in bulk measurements. With the stimulation, gradual and long heat generations were caused similarly with bulk measurements. We have succeeded in detecting the heat from single brown fat cell by using the fabricated device.
