Short-term temperature change detections and frequency signals in single cultured cells using a microfabricated thermistor

Thermal detection is an effective means of investigating the thermodynamics, metabolic mechanisms, and functions of cells. Here, a sensing device for performing thermal measurements in single cultured cells is fabricated, and its characteristics are evaluated. Moreover, temperature detection in single cultured cells was demonstrated. The device is composed of vanadium dioxide (VO₂) microthermistors on a suspended SiO₂ membrane with a polydimethylsiloxane (PDMS) chamber. We demonstrated temperature sensing of single cultured cells on the sensor surface inside a PDMS chamber. The dimensions of the sensors were 50 × 50 μm², almost similar to that of the cultured cells; a single cell was occasionally cultured on the sensor. To observe thermal change of these cells upon stimulation, COS7 cells were used. Their temperature gradually increased by 1 °C in the order of minutes. Furthermore, short-term periodic temperature variations (i.e. spikes) were observed in the non-stimulated cells, while there were no responses in the absence of cells on the sensors. The spikes of large signal amplitude observed at 37 °C confirmed the validity of the observed signals, as cells are active near 37 °C and activated cells emit signals with large amplitudes. The fabricated device can monitor short-term temperature changes in cells and is thus applicable to further investigations which seek to clarifying the thermodynamics, metabolic mechanisms, and functions of cells.