Akther Asma, Castro Jasmine O, Mousavi Shaegh Seyed Ali, Rezk Amgad R, Yeo Leslie Y
School of Engineering, RMIT University, Melbourne, VIC 3001, Australia.
Soft Matter. 2019 May 22;15(20):4146-4152. doi: 10.1039/c9sm00479c.
Tactile haptic feedback is an important consideration in the design of advanced human-machine interfaces, particularly in an age of increasing reliance on automation and artificial intelligence. In this work, we show that the typical nanometer-order surface displacement amplitudes of piezoelectric transducers-which are too small to be detectable by the human touch, and constitute a significant constraint in their use for tactile haptic surface actuation-can be circumvented by coupling the vibration into a liquid to drive the deflection of a thermoplastic membrane. In particular, transmission of the sound energy from the standing wave vibration generated along a piezoelectric transducer into a microfluidic chamber atop which the membrane is attached is observed to amplify the mechanical vibration signalling through both the acoustic radiation pressure and the viscous normal stress acting on the membrane-the latter arising due to the acoustic streaming generated as the sound wave propagates through the liquid-to produce 100 μm-order static deflections of the membrane, upon which approximately 0.5 μm dynamic vibrations at frequencies around 1 kHz are superimposed; both these static and dynamic responses are within the perception range for human finger sensation. The large static deformation, the relatively fast response time, and the ability to incorporate a dynamic vibrotactile response together with the small size and potential for integration of the device into large scale arrays make this mechanism well suited for driving actuation in devices which require tactile haptic responses.
触觉反馈是先进人机界面设计中的一个重要考量因素，尤其是在一个对自动化和人工智能依赖日益增加的时代。在这项工作中，我们表明，压电换能器典型的纳米级表面位移幅度——小到人类触觉无法察觉，这在其用于触觉表面驱动时构成了重大限制——可以通过将振动耦合到液体中以驱动热塑性膜的挠曲来规避。具体而言，观察到沿压电换能器产生的驻波振动的声能传输到附着有膜的微流体腔室中，通过作用在膜上的声辐射压力和粘性法向应力放大机械振动信号——后者是由于声波在液体中传播时产生的声流而产生的——从而使膜产生100微米级的静态挠曲，在其上叠加频率约为1kHz的约0.5微米的动态振动；这些静态和动态响应都在人类手指感觉的感知范围内。这种机制具有大的静态变形、相对较快的响应时间、结合动态振动触觉响应的能力，以及小尺寸和集成到大规模阵列中的潜力，使其非常适合在需要触觉反馈的设备中驱动致动。
