Multi-modal Haptic Stimulations Using Micromachined Ultrasound Processors

具有多种功能的新兴可穿戴电子产品在无缝人机界面应用中是理想的，包括检测环境信号的传感器和产生机械感觉的执行器。今天，许多传感系统已经开发用于人机界面，以感知信号，如与人体健康状况相关的生理参数，包括心电信号、脉搏波、血压和身体运动。另一方面，可穿戴式机械刺激器的进展仍然非常具有挑战性。例如，传统的驱动系统使用大型线性谐振器、偏心旋转质量和音圈来产生机械刺激。因此，这些系统体积庞大，通常是固定的，应用非常有限。在不同的研究阶段，有几个“可穿戴”原型刺激器，比如指尖上的触觉设备，用于虚拟现实应用，以重现交互力，但这些系统仍然体积庞大。为了解决基于压电聚合物的柔性、薄型和轻量化致动器的尺寸问题，已经报道了几种柔性和薄型致动器。然而，它们需要非常高的驱动电压（数百伏），并且它们没有很好的空间分辨率来模拟多模态刺激来模拟复杂的感觉。该项目利用压电微机械超声换能器（PMUTs）的声压，通过微加工工艺构建小尺寸、可穿戴、非接触式触觉反馈系统，为低成本制造提供了独特的机会。制造、材料科学和物理转导原理之间的研究和教育互动和整合的协同作用将成为下一代科学家和工程师在研究和教育专业知识方面的多学科融合的引擎。可穿戴触觉设备的理想特征包括：(1)低驱动电压和高输出力和/或变形；(2)薄型小尺寸结构；(3)具有高时空分辨率的多模态刺激。本项目提出了三种创新方法来解决这些挑战：(1)压电微机械超声换能器（PMUTs）阵列，用于产生高超声辐射力，用于与皮肤表面轮廓无关的非接触刺激；(2)采用单个PMUT芯片和多个驱动器单元实现高时空分辨率；(3)通过对单个执行器的振幅和频率调节来改变触觉的模态。因此，这种微机械超声处理器可以在各种当前和未来的系统中实现特殊的功能和用途，包括手机，增强现实（AR），虚拟现实（VR），机器人等，通过提供当前触觉反馈设备无法实现的替代/额外触觉刺激。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.