Next-Gen Sensor Technologies for New Applications

A new generation of sensors has begun to emerge from research laboratories. These devices are leveraging new materials, form factors and design techniques to push the limits of sensitivity, response time and operating range. Demands for new applications are shaping the efforts to develop these sensing devices, with an eye on delivering functionality that older technology simply cannot.

These developments open doors for sensing devices to play new and unique roles in health care and wearable designs with emphasis on providing almost unprecedented levels of sensitivity. All this is part of the movement to realize the concept of sensing everything.

Beyond Electronic Skin

One such application driving research efforts seeks to impart human sensing capabilities to prosthetics and robots via electronic skin. Until recently, development efforts in this area fell short, failing to deliver the full range of human tactile senses due to inadequate sensitivity.

Researchers at China’s Harbin Institute of Technology, however, may have devised a way to make up for these shortcomings. They have built a sensor that emulates the fine hairs that cover most of the human body and relay sensory information to nerves in the skin. To deliver the same level of sensitivity found in these hairs, the researchers used wires 30 micrometers thick—about the size of a human hair—embedded in silicon, which acts like skin.

While past efforts to produce hair-like sensors have incorporated carbon nanotubes, this new design uses glass-coated wires made of a strong, flexible and conductive cobalt alloy. Unlike earlier designs that sensed pressure or motion, the wires in the new design sense changes in a magnetic field created by an electrical charge running through the wires. The magnetic field changes when one or more hairs move from their original position.

One of the greatest successes of the technology is its impressive sensitivity. The artificial hair has demonstrated that it can detect the presence of a fly, a light breeze or an object being dragged across the hair in different directions. In addition, the structure can withstand 50 Newtons.

This sensing mechanism promises to enable a new strategy for designing multifunctional tactile sensors with great potential for expanding the capabilities of prosthetics and robots in harsh environments. In one test, the researchers attached the sensors to a gripper on a robot arm. The device acted like the pad on the tip of a finger, helping the robot to judge how tightly to grip objects.

From Child’s Toy to State-of-the-Art Sensor

Of all the sensor technologies emerging from research and development labs, the composite material called G-putty makes you want to shake your head in disbelief. Researchers from Trinity College Dublin and the University of Manchester have combined graphene with a homemade Silly Putty-like polymer to create a pressure sensor sensitive enough to detect the footsteps of a spider.

Each element that makes up the enhanced putty delivers unique properties. The polymer flows like a viscous liquid when deformed, but it bounces like an elastic object when it strikes a hard surface. The graphene, on the other hand, creates electrical resistance that increases significantly when the composite experiences the slightest strain or impact. Following this reaction, the resistance slowly returns to its original state as the putty “heals.”

The developers contend that the remarkable features of the technology will create new opportunities for manufacturing biomedical sensors, enabling the production of devices that can enhance disease diagnosis and treatment monitoring. One possible application would involve laying the G-putty onto a person’s neck, chest or back to allow healthcare providers to measure vital signs like heart rate, blood pressure and breathing.

Much like the artificial hair discussed earlier, one of the most impressive features of G-putty is its sensitivity to strain and pressure. Testing has shown that these devices are hundreds of times more sensitive than traditional sensors. See it in action in the video below.

Signs of Things to Come

Both the technologies examined here show how new materials and design techniques radically change the form and function of sensors in response to new application demands. The new materials have enabled developers to create devices that deliver performance that could not be achieved with older technologies and thus set a new standard for the next generation of sensors.