Microcantilever sensors are highly sensitive tools in biomedical applications to measure small scale mechanical movement, including the measurement of contractile force of muscle tissues using in vitro human-on-a-chip systems. Typically, these microcantilevers are monitored using imaging methods or optical laser deflection of cantilevers for calculating contractility. Piezoelectric materials have the ability to convert mechanical energy to an electrical signal leading to their use in a variety of microscale sensor systems such as chemical sensors and biosensors. They also have the ability to convert electrical signals to mechanical energy which has led to their use as microactuators. Incorporation of piezoelectric materials into cantilever-based mechanical sensors would enable a direct electrical readout during muscle contraction. A microcantilever device incorporating a piezoelectric material was designed and created to act as either a sensing element for tissue contraction or as an actuator to apply mechanical force to cells. Piezoelectric cantilevers were created by fabricating a thin film of piezoelectric aluminum nitride (AlN) on microscale silicon cantilevers. They were used to monitor the contractility of iPSC-derived cardiac muscle and human primary skeletal muscle tissues which were grown on top of the cantilevers. Platinum wires and interconnects allowed the connection of the piezoelectric elements to an external amplifier to record the electrical signal generated in the aluminum nitride caused by the muscle tissue bending the cantilever. The amount of force generated by the muscle tissue was directly calculated from the cantilever deflection using Stoney’s equation for thin film stress. The ability of the piezoelectric cantilevers to actuate instead of sense was evaluated by applying a periodic voltage to the interconnects and observing the cantilever deflection using an optical beam displacement method. This novel sensor has the potential for incorporation into human-on-a-chip systems for basic physiological investigation and pharmaceutical compound development, cosmetics toxicity testing, and personalized medicine.<br/>

Novel piezoelectric microcantilever sensor for measurement of contracting muscle force generation

2019 Spring National Meeting

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