Novel Piezoelectric Device for Inducing Strain on Biological Tissue At High Speed

A novel mechanically amplified piezoelectric device is presented that induces large complex strains on biological tissue at high speeds. This device allows for the mechanotransduction process (translation of mechanical forces into biochemical signalling) to be studied for different biological tissues, such as single-layered cultured cells on an elastomer membrane or mammalian tissue samples. Two compliant rhombus mechanical amplifiers in a nested configuration are used to overcome the common limitation of piezoelectric actuators of low relative displacement. The device applies a maximum of 84.2% uni-axial tensile strain and a recorded strain rate of 28.8%/ms over a 1 mm long sample, thereby able to reproduce not only physiologically-relevant strain profiles (strains felt by cells from normal bodily function) but also extreme mechanical environments (high strain rates such as from blunt force impacts). A conventional PI feedback controller is implemented to accurately follow complex strain-time profiles with a recorded average standard deviation of 0.12% strain. Experiments such as strain felt by cardiac tissue during a heartbeat or a blunt force impact to the brain causing traumatic brain injury can be realised with the proposed device. Our device will allow researchers to create more accurate simulations of the mechanotransduction processes in vitro, providing the opportunity to gain a greater understanding of different diseases and injuries.