Cell-based sensors are being developed to harness the specificity and sensitivity of biological systems for sensing applications, from odor detection to pathogen classification. These integrated systems consist of CMOS chips containing sensors and circuitry onto which microstructures have been fabricated to transport, contain, and nurture the cells. The structures for confining the cells are micro-vials that can be opened and closed using polypyrrole bilayer actuators. The system integration issues and advances involved in the fabrication and operation of the actuators are described.