Scientists have created a touch interface that, while smooth, can provide the user with a simulated sensation of a variety of surfaces, including that of a sharp blade or needle (from MIT Technology Review).
By controlling the direction in which pressure is applied to the skin when a user's finger is run across the smooth surface, the brain can be tricked into feeling a variety of pointed or textured objects where there are none. Essentially, this is the touch equivalent of an optical illusion.
While this technology is still in the earliest stages of laboratory testing, within 15 years, it will be commercially viable. By then, it will find many uses in medicine, defense, education, entertainment, and the arts. Examples of practical applications include training medical students in surgical techniques, or creating robots with hands that can perfectly duplicate human characteristics.
This will be one of the critical components of creating compelling and immersive virtual reality environments, and the progress of this technology between now and 2020 will enable prediction of the specific details and capabilities of virtual reality systems for consumers. A fully immersive VR environment available to the average household has already been predicted here, and now one more key component appears to be well on track.
Update : More from Businessweek