LRAir: Non-Contact Haptics Using Synthetic Jets (2022)
Haptic devices are incredibly diverse. They come in all shapes and sizes and can be designed to interface with any of the numerous kinesthetic or cutaneous haptic modalities that humans possess. This is evidenced by the equally diverse range of research which all falls under the name "haptics". A haptic device can be a high powered robot arm or a tiny stimulating electrode on the skin. When it comes to haptic interfaces in the everyday world, however, vibration actuators dominate. This typically means eccentric rotating masses (ERMs), in devices such as game controllers, or linear resonant actuators (LRAs) in devices such as smartphones and wearables. These actuator types are so successful that they have reached near ubiquity. Part of the reason for this is because the barriers to implementing these devices are incredibly low. They are simple in concept (shaking or rotating mass), and do not require much power, voltage, or electronics to drive. Most of the time less than a watt, 2-5 volts, and an audio type amplifier suffices. This translates to low cost with high enough performance for basic functionality, such as notifications.
While ERMs and LRAs have taken over the world of mobile touchscreens and other contact-based interactions, there is a growing number of non-contact interactions which we believe are under-served by current haptic devices. These interactions are based around midair hand and finger gestures, and have application use cases such as automotive dashboards, retail kiosks, extended reality (XR) systems, and internet of things (IOT) devices. The most promising approach to date to serve these use cases has been ultrasonic midair haptics, however we believe that this area, as a whole, can benefit from additional novel actuation techniques.
It is with this context in mind that we propose LRAir, a non-contact haptic actuation method that uses zero-net-mass-flux (ZNMF) jets of air (also known as "synthetic jets") to direct mechanical energy to the skin. This new class of haptic actuator uses a seemingly simple design, an oscillating membrane in an enclosed cavity with a hole in it, to generate localized impulses of high velocity air. These impulses, when felt by a user with their hand over the air jet, readily produce sensations of impact, vibration, pressure, and cooling.
Award: Best Paper Award
Citation: Craig Shultz and Chris Harrison. 2022. LRAir: Non-Contact Haptics Using Synthetic Jets. In 2022 IEEE Haptics Symposium (March 21 – 24, 2022). HAPTICS '22. IEEE, Washington, D.C.