A research team led in part by Huanyu “Larry” Cheng, James L. Henderson Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State, is developing a highly sensitive electronic “skin” for robots and prosthetic limbs using pressure sensors—tiny, paperclip-sized devices capable of measuring force across a surface.
Cheng is a corresponding author of a recent paper published in Nano-Micro Letters that presents an enhanced pressure sensor design. The team’s sensors form a wireless array that detects pressure patterns, interprets hand gestures, and differentiates foods by weight and texture.
In the following Q&A, Cheng explains pressure-sensing technology and how his team’s work could enable robots to more accurately “feel” touch.
Balancing Sensitivity and Accuracy in Pressure Sensors
Despite extensive research, flexible pressure sensors still struggle to combine high precision with responsiveness to very light forces. Traditional designs use dense conductive networks, but their irregular structures reduce strength, detection range, and durability.
To address this, we developed a flexible sensing platform using reduced graphene oxide aerogel (rGOA), an ultralight, oxygen-rich material. Through freeze casting, we created sensors with an anisotropic microstructure, giving them direction-dependent mechanical strength.
These improvements allow our sensors to achieve exceptionally high sensitivity, a wide pressure detection range, and strong long-term stability. Although each sensor measures only about eight millimeters, it can withstand repeated loading—over 20,000 cycles—while supporting small forces. When combined into an interconnected array, they form an artificial “skin” capable of detecting extremely subtle pressure changes with high precision.
How Are The Sensors Constructed, and How Did You Evaluate Their Performance?
The pressure sensor was built by placing rGOA between a synthetic, plastic-like film patterned with interdigital electrodes—silver-ink printed measurement elements—and a thin layer of silicon-based polymer. This layered structure ensures strong electrical contact, durability, and flexibility for real-world use.
To evaluate performance, we measured current responses across a wide range of pressures, along with frequency behavior and stability under varying temperatures and humidity. The sensors showed exceptional sensitivity—nearly double that of conventional designs.
They also demonstrated rapid performance, responding to pressure in just over 100 milliseconds and recovering in about 40 milliseconds, significantly faster than many existing sensors, which can take more than 250 milliseconds to complete a full cycle.
Building Artificial Skin: Assembly and Applications
The sensors can be arranged into arrays that gather multiple data points at once. A microcontroller processes these signals, converting them into digital data and displaying them in real time, allowing precise detection of pressure location and intensity—useful for prosthetics, robotic handling, and battery monitoring.
Thanks to their flexibility, high sensitivity, and environmental stability, the arrays can conform to complex surfaces for accurate pressure mapping. This enables advanced uses in smart robotics, wearables, and human–machine interfaces, including detecting subtle changes from irregular objects.
One important application is the early detection of battery swelling in electric vehicles, helping prevent serious damage. The sensors can also recognize object shapes and assist robots in handling delicate items. Integrated with robotic hands or grippers, they provide real-time force feedback, allowing safe manipulation of fragile materials like tofu, cotton, and steamed buns—enhancing precision in human–machine interaction.
Future Directions and Commercial Prospects
We aim to make the sensors smaller and lighter to improve biocompatibility and performance in challenging environments. Future research may allow spatially programmable sensitivity, letting a single sensor or array detect delicate pressures in one area while handling heavier loads in another, and potentially combining pressure, temperature, and strain sensing into one integrated system.
We see strong potential for real-world use and commercialization, particularly in wearable devices and commercial robotics. Sensor arrays could provide an affordable, high-performance solution that remains flexible and customizable.
Read the original article on: Tech Xplore
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