Imagine a touch sensor so thin and flexible it can feel not only where you press but also how hard.
Scientists in Japan have just developed such a device, and it could transform everything from robotics and prosthetic limbs to medical tools and wearable electronics.
The research team at Keio University designed a new kind of optical touch sensor that works differently from traditional ones.
Most touch sensors today have just one optical path, limiting them to simple inputs and making them harder to scale.
This new version, however, embeds several light-guiding channels—called polymer optical waveguides—inside a sheet of silicone rubber.
That means the sensor can detect multiple points of pressure at once while also measuring how strong each touch is.
The team built a prototype sensor about the size of a stick of gum, measuring 5 by 1.5 centimeters and just half a millimeter thick.
Despite its small size, it proved remarkably sensitive. It could detect fingertip pressure as light as a tap on a smartphone screen, locate the touch point within 1.5 millimeters, and measure changes in pressure strength in as little as 33 milliseconds.
To create this breakthrough, the scientists used their unique “Mosquito method.” The name comes from the way a syringe injects liquid resin into a thin silicone sheet, a bit like a mosquito drawing blood.
Once cured with ultraviolet light, the injected resin hardens into tiny, flexible optical channels that guide light in much the same way as traditional glass optical fibers.
But unlike glass fibers, these polymer channels can be freely shaped, allowing the researchers to design multiple paths inside a single thin sheet.
Here’s how it works: in normal conditions, light passes smoothly through all the channels. When a fingertip presses down, the silicone compresses, bending one of the channels. If the bend is sharp enough, some of the light leaks out, dimming the signal.
By monitoring which channels dim and how much, the system can tell both the location and the force of the touch.
The team tested the sensor using controlled fingertip pressure and force gauges, finding it not only highly accurate but also durable. The sensor recovered quickly after repeated use, maintained stable performance, and showed excellent repeatability.
Lead researcher Takaaki Ishigure believes this could be a game-changer.
For robots, it could mean lifelike touch sensitivity, making human–robot collaboration safer and more natural. For healthcare, it could be built into prosthetic limbs to restore a sense of touch, allowing wearers to grip and manipulate objects more easily.
Looking ahead, the team plans to improve the sensor’s resolution and expand it into three-dimensional designs that can cover larger surfaces.
They are also working on lowering costs and making the process more practical for everyday devices.
If successful, the technology could lead to a future where machines and humans interact through touch as naturally as they do through sight and sound.
