Electrotactile arrays are a lesser-known form of human-machine interface (HMI) that apply electric current to skin-contacting surface electrodes to excite cutaneous nerves and give the illusion of texture, pressure, or pinpricks (depending on current strength and electrode resolution) all without mechanical vibration. This technique has been around for many years for: non-visual fighter pilot status displays, tongue interfaces, surgery guides, and for forehead-mounted camera displays for the blind. Enough background... The exciting news is a recent product developed by Senseg and Toshiba Information Systems called "E-Sense" that successfully embeds an electrotactile display into a touchpad, LCD, or other curved surface (eg. all over a cellphone), thereby providing programmable high-resolution texture feedback to a user -- see the video embedded below. I would wager that this feedback could greatly enhance haptic shared awareness in teleoperation / telemanipulation systems.
Update August 15th, 2010: Mr. Kurt Kaczmarek, an expert in this area and co-developer of the BrainPort with Dr. Paul Bach-y-Rita, provides a correction: The Senseg device is actually causing deflections of the skin through electrostatic forces, making it an electrostatic variant of vibrotactile (sometimes referred to as electrovibration) rather than being electrotactile -- see the comments for more extensive clarification.
The idea of using electrotactile feedback in robotics isn't entirely new. Two papers (one and two) in the year 2000 explored the technology for user feedback during robotic manipulation. However, I don't believe they closed the book on the subject; recent advances in electronic integration (eg. in the video), miniaturization, and form-factor (eg. textiles) could offer vastly superior implementations and capabilities, especially if coupled to a texture classification system on the robot. Just remember: If you happen to act on the idea I'm sharing, gratuitous collaboration and co-authorship is always welcome. ;-)
I have no intent to provide a lengthy diatribe about the "coolness" of electrotactile displays, nor their vibrotactile cousins (eg. cellphone "vibration" motors). So instead, here's a quote from HowStuffWorks:
What we're talking about here is electrotactile stimulation for sensory augmentation or substitution, an area of study that involves using encoded electric current to represent sensory information -- information that a person cannot receive through the traditional channel -- and applying that current to the skin, which sends the information to the brain. The brain then learns to interpret that sensory information as if it were being sent through the traditional channel for such data. In the 1960s and '70s, this process was the subject of ground-breaking research in sensory substitution at the Smith-Kettlewell Institute led by Paul Bach-y-Rita, MD, Professor of Orthopedics and Rehabilitation and Biomedical Engineering at the University of Wisconsin, Madison.
It is only fair to point out that two of my acquaintances (Seungyon Claire Lee and Dr. Thad Starner) championed wearable, textile electrotactile displays: "Stop Burdening Your Eyes: a Wearable Electro-Tactile Display" and "Mobile Gesture Interaction Using Wearable Tactile Displays." Some time ago I was an early user-study participant for their system and infrequently consulted them on the electronics; more pointedly, our conversations drove my curiosity to explore this neat technology. Congrats on your recently-conferred PhD, Seungyon!