An apparatus for high throughput nanomechanical muscle cell experimentation

An array of independent muscle cell testing modules is being developed to explore the mechanics of cardiac myocytes. The instrument will be able to perform established physiological tests and utilize novel system identification techniques to measure the dynamic stiffness and stress frequency response of single cells with possible applications in the pharmaceutical industry for high throughput screening. Currently, each module consists of two independently controlled Lorentz force actuators in the form of stainless steel cantilevers with dimensions 0.025 mm x 0.8 mm x 3 mm, 0.1 m/N compliance and 1.5 kHz resonant frequency. Confocal position sensors focused on each cantilever provide position and force resolution < 1 nm/square root Hz and < 10 nN/square root Hz respectively. The motor structure can produce displacements > 0.1 mm and forces > 0.1 mN. A custom Visual Basic.Net software interface to a National Instruments data acquisition card implements real time digital control over 4 input channels and 2 output channels at 20 kHz. In addition, algorithms for both swept sine and stochastic system identification have been written to probe mechanical systems. The device has been used to find the dynamic stiffness of a 5 microm diameter polymer fiber between 0 and 500 Hz.