In a groundbreaking leap for robotics and bio-mimicking applications, scientists have engineered touch sensors that redefine sensitivity by operating without direct physical contact. These sensors, developed by a team at Qingdao University in collaboration with researchers from China and South Korea, have the remarkable ability to detect interference in the electric field between an object and the sensor, even from a distance of up to 100 millimeters. Published in the prestigious journal Science and Technology of Advanced Materials, this innovation heralds a new era of touchless interaction and data transmission.
Traditionally, electronic skins have been pivotal for bionic robots, enabling them to swiftly detect and respond to external stimuli. These sensors typically rely on physical touch to induce a deformation in a contact layer, altering electrical capacitance. However, the uniformity of this response across different regions has limited their sensitivity and functionality.
"To enhance sensitivity and versatility, we devised composite films with extraordinary electrical properties," explains Xinlin Li, a key member of the Qingdao University research team.
The breakthrough came with the fusion of two materials boasting high dielectric constants, resulting in a composite with unexpectedly low dielectric constant—a counterintuitive discovery ideal for crafting highly responsive sensors. This composite, comprising graphitic carbon nitride and polydimethylsiloxane, can be synthesized and processed using a specialized 3D printing technique known as dispensing printing. This method affords precise control over the structure and pattern of the printed high-viscous ink, enabling the creation of a sensor grid capable of detecting objects from 5 to 100 millimeters away without physical contact.
"Our experiments, utilizing the researchers' fingers as proximal objects, demonstrated outstanding performance in sensitivity, response speed, and durability," notes Li. "This breakthrough opens avenues for wearable technologies and electronic skins, promising applications in medical monitoring and the rapidly evolving realm of the internet of things (IoT)."
Integration of the sensing grid into printed circuit boards facilitates seamless data transmission over prevalent 4G networks, compatible with mobile phones.
Looking ahead, the team aims to optimize the technology for mass production while exploring broader applications beyond shape and movement detection. The sensor array's ability to sequentially respond holds promise for human-computer interaction, including gesture recognition. Moreover, its efficacy in contactless systems hints at its potential in human motion detection for applications such as obstacle avoidance and gait monitoring, paving the way for intelligent medical care.
