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Cells play a very important role in biological experiments. To effectively detect cell activity, we fabricated a biomicroelectrode chip for cell activity detection using a semiconductor process, and then completed the package of a cell activity sensor by bonding the bio-microelectrode chip to a PCB using wire bonding technology and completing the encapsulation of the cell culture chamber on the bio-microelectrode chip. To verify the feasibility of the sensor for cell activity detection, CHO cells were grown in the cell culture cavity and cultured for 24 h. TrypLE (an excellent substitute for trypsin) was used to dissociate the adherent CHO and simulate the death of CHO cells, while the output impedance of the sensor was measured. The experimental results showed that the output impedance of the sensor changed significantly at 10^3~10^5 Hz during the gradual dissociation of CHO cells. Combined with the model analysis, it can be tentatively concluded that the sensor has the function of detecting cell activity.

Thermal inkjet three-dimensional (3D) bioprinting (TIJ) is a biological additive manufacturing technology with high cell viability, fast printing speeds, and low costs. It is widely used in biology, chemistry, and pharmaceuticals. In recent years, remarkable results have been achieved in the printing of biological tissues using TIJ. However, few studies have reported on the relationship between TIJ and cell viability. In particular, there have been no reports relating cell viability and the TIJ input energy. In this work, we aim to determine the relationship between the input pulse, printing frequency, and cell viability from the TIJ working principle and find an optimized pulse waveform to improve cell viability. We propose a novel approach to study cell viability. The state of the droplet is observed while controlling the printing pulse and frequency, and then, the corresponding cell viability is determined. The results show that an increase in the pulse increases the shear stress and temperature in the bio-ink, which reduces the viability of the cells. The shear stress and viability of the printed cells show a corresponding piecewise functional relationship. The cell viability is significantly reduced when the ambient temperature is higher than 40 °C. Increasing the printing frequency reduces the rate of printing heat loss, thereby raising the ambient temperature and impairing cell viability. Finally, the optimized input waveform can increase cell viability by up to about 95%.