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*This article is from the 13th issue of Banyuetan in 2024

Why is it so difficult to shake hands with a robot?

A baby can draw lots when he is one year old, but teaching a robot to grasp something is something that cannot be explained clearly even in hundreds of top journal papers.

Scientists tell us that it is more difficult to make a robot pick up a balloon or a glass than to make it play chess like a human, talk like a human, or walk like a human. "Ten years ago, there was a saying in our circle: 'Don't shake hands with robots,'" said Shen Guozhen, director of the Institute of Flexible Electronics and Intelligent Manufacturing at Beijing Institute of Technology.

Why do you say that? What is missing from the way a robot that doesn't know how to shake hands interacts with the world?

Without skin, it's really different

turn out to be--

“In the past, robots had no sense of touch and could not control strength. When shaking hands with people, they did not know when to let go and might accidentally crush the bones in the person’s hand.” Shen Guozhen’s answer revealed a major problem in robot research - robots are missing one human organ, and it is the largest one: skin.

Without skin, it would be difficult for robots to have a developed sense of touch. One of the classic robot images in film history, "Edward Scissorhands", is prone to accidentally hurting people, and this scene is still common in today's robot laboratories.

That’s why we’ve been talking about robots writing essays and playing chess, but we haven’t heard of robots completing housework skillfully.

The sense of touch is actually a combination of multiple sensory information: the location of contact, the size and direction of the contact force, the temperature of the contacted object (or even the untouched object), the texture and hardness... Our skin can capture every bit of this information very subtly and transmit it to the brain, thus initiating many of our reactions and actions that we are accustomed to without noticing.

It can be said that the skin is not only a layer of nearly 2 square meters of attachment on the surface of the body, but also a communication link and interaction method between people and the surrounding world.

So, how about giving robots a skin? Can robots sense and adapt to their environment like humans?

Robotic hand equipped with bionic 3D electronic skin interacts with human hand

What does electronic skin look like?

Of course, not all robots in movies are like Edward.

Although the protagonist of the sci-fi movie "Alita", the robot Alita is thin, she is a "hexagonal warrior". Her fighting power comes from a body of "black technology", including electronic skin with a more sensitive sense of touch than humans.

Yes, electronic skin. Allowing robots to fully perceive their own bodies and surrounding environment, electronic skin has become an important research field in today's robotics.

With the help of electronic skin, robots can more fully and accurately read pressure signals in the environment, and their actions will be more flexible and effective. Generally speaking, current robots lack accurate force feedback on objects, making it difficult to accurately grasp and manipulate tiny or soft objects. Electronic skin can give future robots a pair of "skillful hands", making it easy to perform high-precision surgeries.

So what exactly is electronic skin?

Shen Guozhen introduced that human skin is composed of epidermis, dermis and subcutaneous tissue, and electronic skin is also a similar "sandwich" structure, consisting of electrode materials, active materials and flexible substrates. The electrode materials are located on both sides of the active materials as electrical connection layers to receive and transmit electrical signals; the function of the active materials is to convert environmental stimuli into detectable electrical signals; the flexible substrate is responsible for supporting the electronic skin and attaching it to the robot body.

What problems must be solved when developing an electronic skin? The first problem is the "flexibility" of the material. The key to electronic skin is the word "flexibility". The material that can be used as skin must be flexible and stretchable, not hard and brittle. How is "flexible around fingers" possible?

There are three directions of exploration in the scientific community. The first focuses on physical flexibility and strives to develop materials with smaller scales. For example, soft and highly biocompatible nano-silicon can be used as a biochemical sensor to achieve skin functions to a certain extent. The second is to rely on structural flexibility. Efforts are made to develop various novel mechanical structures of materials such as metals, springs, spirals, snakes... to transform traditional hard materials into new materials with good stretching and bending capabilities. Other scientists are trying to break through intrinsic flexibility and change the properties of polymer materials through polymer engineering to make them have high stretching properties and even self-healing functions.

To develop electronic skin, we must also work hard on the perception function. Sensing is the basis for machines to perceive the environment. It requires sensors to perceive pressure, temperature, judge different objects being touched, and distinguish whether it is a peach or an egg. Tactile sensors must obtain the various characteristics of the surface of the contacting object as fully as possible, and the sensing sensitivity is particularly high.

The flexible and stretchable multifunctional electronic skin developed by Shen Guozhen's team can be used for real-time monitoring of human physiological signals

In addition, how to efficiently transmit the signals captured by the sensors is also a problem. The key lies in how to minimize the loss of signals during transmission to the robot's "brain"?

Electronic skin, should we get one too?

In fact, electronic skin is not only the next generation of equipment for robots, but we humans also "deserve it".

As virtual reality technology is in the ascendant, electronic skin may be an important aid for humans to roam the metaverse. In the virtual world, electronic skin can restore the sense of touch to the greatest extent possible, not only allowing people to "touch" virtual objects almost realistically, but even restoring the feeling of breeze, water flow, and flames, greatly enhancing the sense of immersion and reality.

In addition, for patients with burns and scalds and amputees, electronic skin can help them regain their sense of touch and continue to enjoy a better life.

What can electronic skin do for ordinary people with healthy bodies and minds? "It can serve as a human health monitoring device. Electronic skin is in direct contact with the human body and can directly measure the real-time status of our body data (such as heart rate, body temperature, blood sugar, blood pressure) through high-precision sensors, which is equivalent to a 'health bracelet' with a leap in precision." Shen Guozhen said that this type of technology is now mature and the products will gradually enter the market.

In fact, scientists have a bolder idea: Can the functions of smartphones be integrated into electronic skin? If the sensors of electronic skin are sensitive enough, the circuits are smooth and the performance is stable, wouldn’t it be logical to send and receive messages and make and receive calls by “clicking” different positions of the electronic skin?

Maybe by then, we can really put down our mobile phones and go out with light luggage.

Original title: "Shake hands with a robot, do you dare?"

Banyuetan reporter: Zhang Manzi/ editor: Fan Zhongxiu

Editor: Qin Daixin / Proofreader: Zhang Ziqing