Effect of mechanical stimuli on live cells in a pneumatically driven cell trap

A pneumatically driven cell trap device with individually controllable vibrators was fabricated and the effect of mechanical stimuli on a trapped live cell was examined. The device consisted of two polydimethylsiloxane (PDMS) layers that formed pneumatic vibrators and a trap chamber connected to a fluid channel for introducing the cell. When the vibrators were supplied with compressed air, the flexible diaphragms in the vibrators were deformed and exerted pressure on the fluid film in the trap chamber. If a cell was present in the trap chamber, drag force generated by the fluid flow affected the cell. By using a symmetrical arrangement of four vibrators, the cell could be manipulated and trapped in region at the center of the four vibrators. In order to verify this working principle, the ability of the device to trap solid particles and live cells was tested. Intracellular calcium levels were measured to investigate the influence of mechanical stimuli produced via the fluid film, which was induced by pneumatic actuation, on a single cell within the trap chamber. Once the vibrators were actuated, the intracellular calcium level of the cell at rest increased rapidly as it responded to the external mechanical stimulation induced by deformation of the vibrator. When considering the typical increases in calcium induced by shear stress, the measured peak value was very small. As the duration of trapping was prolonged, the calcium levels decreased. The calcium level was comparable to that of a cell at rest, with some fluctuations. In short, the influence of mechanical stimuli on a live cell induced by the pneumatic cell trap appeared to be negligible during trapping.