High-Resolution Thin-Film Device to Sense Texture by Touch

Abstract

Touch (or tactile) sensors are gaining renewed interest as the level of sophistication in the application of minimum invasive surgery and humanoid robots increases. The spatial resolution of current large-area (greater than 1 cm 2 ) tactile sensor lags by more than an order of magnitude compared with the human finger. By using metal and semiconducting nanoparticles, a ∼100-nm-thick, large-area thin-film device is self-assembled such that the change in current density through the film and the electroluminescent light intensity are linearly proportional to the local stress. A stress image is obtained by pressing a copper grid and a United States 1-cent coin on the device and focusing the resulting electroluminescent light directly on the charge-coupled device. Both the lateral and height resolution of texture are comparable to the human finger at similar stress levels of ∼10 kilopascals.

Linear Tactile Nanodevice with Resolution on Par with Human Finger

“…The film is insulating in the in-plane direction (6). In the vertical direction, the film is conducting due to tunneling between the Au and CdS layers.…”

“…The current tactile devices with active area of over 1 cm 2 have a resolution of ~1-2 mm (3) in contrast to human finger that has a resolution of ~40 μm (4) allowing us to feel a filament of hair on a smooth surface that has a typical diameter of ~100 μm. Recently, by self-assembling layers of nanoparticles by simple solution deposition process invented by Decher (5) we fabricated a large area device of thickness ~100 nm to convert compressive stress distribution or pressure on physical contact to light (6). By imaging the distribution of emitted light on a digital camera a "stress image" can be obtained that resolves the distribution of contact-pressure at a resolution of ~20 μm (6).…”

“…Recently, by self-assembling layers of nanoparticles by simple solution deposition process invented by Decher (5) we fabricated a large area device of thickness ~100 nm to convert compressive stress distribution or pressure on physical contact to light (6). By imaging the distribution of emitted light on a digital camera a "stress image" can be obtained that resolves the distribution of contact-pressure at a resolution of ~20 μm (6). Apart form the resolution on par with human sensitivity at contact pressures of 10-60 KPa that are comparable to the human touch, the approach has two practical advantages: (a) The fabrication process that is essentially sequential dip-coating followed by washing and drying will allow deposition of thin film device on large surface of area comparable to displays.…”

Interactive Scanning of Haptic Textures and Surface Compliance

“…The surface texture could also be measured with an array of pressure sensors. These kind of sensors have been used for tactile sensing in robotics and haptics [16] and the resolution of recent experimental devices reportedly approach the resolution of a human fingertip [17].…”

Improving the Mobility Performance of Autonomous Unmanned Ground Vehicles by Adding the Ability to ‘Sense/Feel‘ Their Local Environment

“…The first type of feel sensor is being developed for use in minimally invasive surgery. Maheshwari [14] and Saraf [15] have developed these sensors by using metal and semiconducting nanoparticles in a small area which are so precise that they can feel the shape of the head on the back of a coin. Future work with these touch sensors is in detecting cancer cells by feeling their hardness.…”