New fabric allows secure payments and health monitoring with a swipe of the sleeve

With the rapid development of science and technology, human-computer interaction has gradually integrated into our lives. Whether we are using mobile phones, computers, smart bracelets and other electronic products, we are interacting with humans.

Have you ever thought about:

Mobile payment no longer requires scanning, you can pay securely with just a swipe of your sleeve;

You no longer need a smart bracelet to monitor your health. You only need to put on clothes to get your physical data in real time.

You no longer need a key to start the car. You only need to sit in the seat and the car will recognize your clothes and follow your instructions.

......

These imaginations sound sci-fi and far-fetched, but now scientists have made them a reality.

Recently, Professor Peter Tseng's team at the University of California integrated advanced magnetic metamaterials into flexible textiles to create a system that enables battery-free communication between clothing and nearby devices.

The textiles could allow wearers to digitally interact with nearby electronic devices, such as making secure payments with a simple touch or swipe of the sleeve, and continuously monitor and transmit vital signs.

(Source: Nature Electronics)

The related research paper, titled “Textile-integrated metamaterials for near-field multibody area networks”, was published in the scientific journal Nature Electronics.

Adding NFC to wearable devices

In 1975, the first calculator watch came out and smart wearable devices began to enter our lives.

With the development of technology, more and more smart wearable devices appear in our lives, such as smart bracelets, smart glasses, smart fabrics and so on.

These smart wearable devices allow people to process external information more efficiently and monitor human activities or health.

Currently, human health monitoring and activity tracking technologies rely primarily on wearable or implantable sensors that create multi-node networks that interpret information from our body’s interactions with objects.

In order to parse this biometric information in real time, such networks require secure and reliable communication links between nodes, which are often referred to as body area networks (BANs).

Creating BANs requires connecting multiple sensors around the body, and in order not to restrict the movement of the human body, most of these sensors use wireless connections.

Traditionally, wireless communications configured in BANs include custom RF sensors, RFID, or Bluetooth. However, these radiation methods usually have problems such as high power consumption and low security (such as being eavesdropped).

The use of near field communication (NFC) can effectively solve the above problems and improve the security of communication.

So what is NFC technology?

NFC is a radio frequency identification technology found in most smartphones. For example, when you hold your smartphone or credit card near a reader to pay, you are using near-field communication technology.

NFC can be used both to supply power to devices and to collect data from them.

As a result, the technology has the potential to eliminate the need for batteries in wearable sensors, making the devices lightweight, long-lasting and less expensive.

Behind this seemingly "perfect" technology, there is a fatal flaw, which is that the communication range is too small and can only achieve short-distance communication of a few centimeters.

It is difficult to establish a full-body connection when using this technology on the human body. (After all, everyone has legs that are 1.8 meters long, so I’m going to give you a dog head.)

To address this issue, the researchers' textiles extend the range of NFC by using tracks through which the signal can propagate with minimal loss.

Figure ｜ BANs based on textile integrated metamaterials. (Source: Commentary article of this paper)

Signal transmission is “extended in all directions”

Inspired by current low-cost vinyl clothing production, the researchers integrated a magnetoelectric induction network onto textiles.

This approach skips the complex sewing techniques and expensive wires required for flexible fabrics in modern wearable devices.

And magnetic metamaterials make it possible for signals to propagate along the track:

These tracks are controlled by individual components with an artificial period. Each unit consists of an inductor and a slotted ground layer. The units are connected together by fixing them to the fabric. Adjacent inductors overlap to form a structure called a magnetic induction waveguide.

When an NFC reader is close to any cell, it can stimulate the voltage and current in the cell, which in turn stimulates the adjacent cells, forming a coupling effect.

This coupling effect causes a cascade of signals along the entire structure, which can be described as a propagating wave.

Figure | Textile-integrated magnetic sensing pathway. a. Resonator fabrication and textile integration steps. b. A magnified image of a resonator showing its stack. c. A variety of flexible resonator designs for optimal signal transmission and power distribution. d. The wearable modular network is integrated into clothing and covered by a transparent thermally conductive vinyl that acts as a mechanical clamp. e. Resonators can be designed to cover a wider near-field area and can be embedded in specially colored vinyl designs. This allows the network to be customized in terms of functionality and style. f. The battery-free NFC transponder is integrated with strain and temperature sensors to transmit the respective sensor states to the NFC reader. (Source: The paper)

The researchers used this effect to create trails that cross the body, split into multiple branches, and span the gaps between different items of clothing.

They liken the technology to "railroads" that, when crisscrossed across a piece of clothing, can transmit power and signals.

Not only does the system make it easy to add new pieces, it also allows different garments to "talk" to each other.

In particular, they note that NFC readers worn in pants pockets could power off-the-shelf sensors placed on the chest, abdomen, knees, and ankles.

Professor Peter Tseng said: "This means you could put your phone in your pocket and simply rub your body against other textiles or readers, and power and information would be transferred across your device."

The innovative design is highly flexible, allowing the pants to measure leg movement while in motion, while communicating with the top, which tracks heart rate and other statistics. Two people wearing the pants can exchange letters by tapping their wrists.

The first author of the paper, Dr. Amirhossein Hajiaghajani, said the medical applications of this technology are countless, such as freeing hospital staff from the task of applying a large number of patient sensors, as these sensors can be integrated into medical uniforms equipped with metamaterials.

Professor Peter Tseng said: "When you suspend the clothing over a wireless reader, the electronic device will send out a signal, so you can share information with a simple high five or handshake."

Figure | Multi-transponder and multi-band communication using textile integrated waveguides. a. Shirt and pants above and below the pants/shirt terminal. The NFC reader receives information from multiple sensors and is connected to an external battery. b. Real-time, short-term, low-speed monitoring of human activities through time-based multi-sensor readings within BANs. c. High-speed, long-term indoor walking/running activity measurement. d. Monitoring sensors during indoor operation at different speed profiles. e. Long-term packet loss monitoring during indoor operation. f. Body-to-body communication is achieved through the plug-and-play nature of NFC and its transmission measured when the hand is brought closer and farther away over a long period of time to obtain various VD values. (Source: This paper)

The researchers say their textile is cheap, easy to make and can be incorporated into interesting wearable designs. Not only that, they hope it can also reduce the burden that modern electronics bring to our lives.

a fly in the ointment

The invention of this technology is refreshing, but there are still some problems that need further research.

The clothes we wear every day are not disposable, so the durability of this fabric is worth considering. The researchers said that this textile can withstand a washing cycle, but to withstand daily wear and tear, more robust conductive materials may be needed.

Second, the interaction of fabrics with more readers or sensors is still a development direction. Whether smartphones and skin-mounted sensors can replace circuit board prototypes to achieve similar performance remains an open question.

Technology makes our lives more intelligent. In the future, we will no longer be satisfied with the connection between machines and conversations between people, but more about the interaction between people and machines.

Through human-computer interaction, we may be able to communicate silently like the Avatars in "Avatar"; we may no longer need to use mobile phone screens, and can operate devices simply through gestures; the development of science and technology will surely bring us more convenience.

References:
https://www.nature.com/articles/s41928-021-00663-0
https://www.nature.com/articles/s41928-021-00674-x
https://techxplore.com/news/2021-11-uci-people-high-five.html

Source: Academic Headlines

Written by: Hao Jing Edited by: Kou Jianchao