Ultrasound can deliver chemical stimulants to the skin and modulate their perception

When applied to the skin, chemical stimulants can evoke haptic sensations. However, they need to be applied continuously using paper or pads in fixed locations, limiting their usefulness as a general haptic technology. To overcome these limitations, we introduce an ultrasound-based system for the precise acoustophoresis of droplets of chemical stimulants to the skin. We show that such droplets can indeed produce distinct haptic sensations. In addition, the system can use ultrasound to stimulate the area of the skin where the stimulants have been applied. We show that this increases the perceived intensity. Taken together, these results demonstrate the promise of non-contact delivery and modulation of chemical stimulants, not only as a haptic technology but also to provide deeper insights into the interaction of the chemical and mechanical senses.