A custom-designed microelectromechanical system (MEMS) force transducer, with a volume less than 1 mm(3), is being fabricated to measure force development in isolated cardiac muscle cells to elucidate the physiology of muscle contraction. A single heart cell is attached to flexible, hinged polysilicon plates submerged in a nutrient saline solution. As the cell contracts, the plates bend, and the contractile force can be measured based on the known spring constant of the plate. The amount of deflection is measured by piezoresistive, ion-implanted strain gauges placed at the base of the plates. Prototype structures have been fabricated and have been mechanically tested using probes. We have demonstrated that living rat heart cells can be attached to polysilicon using a silicone sealant. Polysilicon is an inert material when exposed to cardiac cells and their saline environment and has no effect on the cells themselves.