Multi-modal Haptic Stimulations Using Micromachined Ultrasound Processors

Emerging wearable electronics having a variety of functions are desirable in seamless human-machine interface applications, including sensors to detect environmental signals and actuators to generate mechanical sensations. Today, numerous sensing systems have been developed for human-machine interfaces to sense signals such as physiological parameters relevant to human health conditions, including electro-cardio signal, pulse wave, blood pressure, and body motion.

On the other hand, the progress of wearable mechanical stimulators remains very challenging. For example, traditional actuating systems have used large linear resonators, eccentric rotating masses, and voice coils to generate mechanical stimulations. As a result, these systems are bulky and often stationary with very limited applications.

There are several “wearable” prototype stimulators in various research stages such as tactile devices on the fingertips to recreate interaction forces for virtual reality applications, but these systems are still bulky. Several soft and thin actuators have been reported to address the size issue based on piezoelectric polymers to make flexible, thin, and light-weight actuators.

However, they require very high driving voltage (hundreds of volts) and they don’t have good spatial resolution for multi-modal stimulations to mimic complex sensations. The proposed project provides unique opportunities by using the acoustic pressure of piezoelectric micromachined ultrasonic transducers (PMUTs) to build small-form factor, wearable, touchless haptic feedback systems via the micromachining process for low-cost manufacturing.

The synergy of research and education interaction and integration between manufacturing, material sciences and physical transduction principles will be an engine for the multidisciplinary fusion in research and education expertise for the next-generation scientists and engineers.

The desirable features of wearable haptic devices include: (1) low driving voltage and high output force and/or deformation; (2) thin and small form-factor constructions; and (3) multi-modal stimulations with high spatial and temporal resolutions. This project proposes three innovative approaches to address these challenges: (1) a piezoelectric micromachined ultrasonic transducers (PMUTs) array to generate high ultrasonic radiation force for touchless stimulations irrelevant of skin surface profiles; (2) high temporal and spatial resolutions by a single PMUT chip with multiple actuator units; and (3) varying modals of haptic tactile sensations by amplitude and frequency modulations on individual actuators.

As such, this micromachined ultrasound processor could enable exceptional functions and usages in a variety of current and future systems, including cell phones, augmented reality (AR), virtual reality (VR), robotics, … etc., by providing alternative/additional haptic stimulations that are not possible from the current haptic feedback devices.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.