Nanoelectronics for biology and medicine. Lieber demonstrated the first direct electrical detection of proteins, selective electrical sensing of individual viruses and multiplexed detection of cancer marker proteins and tumor enzyme activity. More recently, Lieber demonstrated a general approach to overcome the Debye screening that makes these measurements challenging in physiological conditions, overcoming the limitations of sensing with silicon nanowire field-effect devices and opening the way to their use in diagnostic healthcare applications. Lieber has also developed nanoelectronic devices for cell/tissue electrophysiology, showing that electrical activity and action potential propagation can be recorded from cultured cardiac cells with high resolution. Most recently, Lieber realized 3D nanoscale transistors in which the active transistor is separated from the connections to the outside world. His nanotechnology-enabled 3D cellular probes have shown point-like resolution in detection of single-molecules, intracellular function and even photons.