A retractable connector includes a base slidably positioned within an electronic card. Also provided are methods of making and using the ion channels formed from a plurality of molecules of the self-assembling compounds. The export directory stores information related to data that has been exported through the agent. Each input network includes a balun and an active decoupling circuit for interconnecting the coil loop and balun. Disclosed are: a cell manipulation apparatus design; various resistive heater configurations for nucleating microbubbles; various well designs, each in communication with a nucleation chamber or channel, for capturing a specified number of cells; and methods of fabrication and cell population manipulation.