No-touch technology has become important for use in contaminated healthcare environments, especially during the COVID-19 outbreak.

"When in the hospital, different people touching the same objects may cause cross infections. Therefore, can we create a way that people can get in without touching the door, or can control other things without touching them?" Researcher Shen Guozhen from the Chinese Academy of Sciences said.

As humans rely more and more on machines to help them, smart sensors are playing a key role, since they can effectively "translate" various signals from the human body into information the machine can recognize.

While most sensors generally detect signals through direct contact such as a pressure sensor, this smart sensor lab is different. You can control the light and even write on a screen without touching it.

This work is based on humidity, that is, water vapor, especially on our fingertips, which have enough water vapor.

In the sensor, scientists place a thin strip of chemical, called molybdenum trioxide, between two electrodes to measure the humidity. The metal oxide can absorb the water in the air, which was provided by your finger. When it becomes moist, its resistance will lower, allowing stronger electric currents to get through. In this way, humidity information will be converted into an electrical signal.

When it absorbs the water vapor, its resistance will change. So, the function of opening and closing can be achieved.

The new design provides a new alternative to no-touch technology.

This prototype sensor allows us to write on a notepad on your computer and to unlock a cellphone without touching anything.

But of course, it still needs a lot of work for the idea to be turned into a real device.

"The sensitivity of molybdenum trioxide is not very good. So we made it into this kind of nano-composited material. We arranged the original device to increase its surface. And actually, it will also reduce the response time and give it more opportunities to make contact with water molecules. In this way, its sensitivity is much improved, and its response is also very fast", Shen added.

The researcher will use special equipment to process molybdenum trioxide. The goal is to make a rougher surface, creating tiny wrinkles, and increase the surface area.

Unlike traditional sensors that have been installed on heavy and rigid surfaces, these sensors are more flexible, twistable, and even stretchable.

Shen said, "because they are made on plastic sheets, they are very thin. In fact, it can be printed, like printing newspapers. Newspapers usually use ink. But when you change the ink into electronic materials, you can print out the active materials and electrodes."

With the high transmission rate of the coronavirus, hospital-wide infections have been widely reported. These clusters of infections have become a big challenge for medical staff around the globe. Measures to control the spread of infection inside hospitals has become more urgent.

Shen hopes for one day, this type of smart sensors will be used to control the doors or other things to avoid cross-infection acquired in the hospital.