Nanodevice for Imaging Normal Stress Distribution with Application in Sensing Texture and ‘Feel’ by Touching

Touch is one of the five senses designed by nature for survival. ‘Touch’ may (partially) be characterized as a sensory operation for measuring texture and softness of an object by mechanical contact. We propose to design, fabricate, study and develop, a novel touch sensor made from nanoparticles with broad range of other applications such as, ultrasound medical imaging/diagnostics, smart materials, and non-destructive diagnostics of large structures. The nanodevice is a self-assembled thin-film sensor that will convert static or dynamic (compressive) normal stress distribution to, (i) visible-light, and/or, (ii) electrical current or voltage. The optical and/or electrical signal is proportional to the magnitude of local stress on the sensor’s active area. By detecting the light intensity distribution and/or, probing the current distribution on the active area using an electrode array, the stress distribution can be obtained at (potentially) spatial resolution of <10 μm spot. Since the device is self-assembled, the sensor surface can be 100 μm to (in principle) over 1 m. Importantly, the dynamic range and the sensitivity of the sensor can be tuned by 1-2 orders of magnitude by regulating the device power supply. Due to high speed (especially for electrical signal), the external stimulus (i.e., stress distribution) may be a pressure or sound radiation. The basic device element is a multilayer film of metallic and (electroluminescent) semiconducting nanoparticles. We have self-assembled a preliminary sensor with active area of 1 cm and sensitivity of ~1 KPa. Since, the total film thickness of the sensor is <100 nm, the normal strain (due to stress) will be highly localized. A patent application on the sensor is filed.