Sensor For Measuring The Mechanical Properties Of Biological Cells

Although many literatures showed that the mechanical stimuli played an importantrole on the cell fate and function, the mechanisms of mechanical stimuli transmitting incells and modulating cells behavior are still not clear. More and more research has beenstarted on this area trying to uncover the mechanisms behind them. Studying themechanisms and processes of mechancial stimuli modulating cells requires us to acquirethe ability that can apply accurate mechanical stimuli on the single cell. We aim todevelop a bioMEMS device, which can apply accurate strain to a single cell whilemeasuring its force response simultaneously, to provide a useful tool for relevantresearchers.Firstly, we studied currently available ways of applying mechanical stimuli to cellsand analyzed their strengths and weaknesses. On this basis, we decide to design a novelbioMEMS device which can stretch a single cell uniaxially. This device utilize thechevron thermal actuator as the uniaxial stretcher and integrate a piezoresistive lateralforce sensor to monitor the cell force response simultaneously. The fabrication processof this lateral force sensor is very simple. It requires only one-step surface implantationand has a low requirement for the alignment.Secondly, a front side releasing method was adopted to release the device. Throughreasonable adjustments of the device sizes and front releasing method processes andparameters, we successfully released the complex structure on uneven wafer surface.This method helps us avoid from the friction problems and low yield rates that commonappeared in the traditional method. Our design provides a good reference for suspendingcomplex microstructures.Finally, devices were measured to characterize their basic performance. The linearthermal actuator produced0to10.9um displacement under0to20volts input voltageor0to642mw input power. And the actuator maintained same stretch performanceunder a0-300Hz input voltage. When the frequency of input voltage exceed1kHz, theactuator showed nearly no displacement. And the force sensor had a sensitivity of33.758(V/V)/N.