Stanford University's flexible product breaks record!

Currently, lightweight, deformable flexible materials are seen as a key breakthrough for intelligent electronic products, and are expected to give rise to many innovative applications. However, the theoretical limits of traditional rigid circuits and the low performance of flexible circuits have restricted the development of flexible electronic products.

Recently, Zhenan Bao, a professor of chemical engineering at Stanford University, published his latest research results in the journal Nature, breaking the previous record of flexible electronic products.

The newly developed intrinsically stretchable circuits are reportedly thousands of times faster than previous intrinsically stretchable electronics and have 20 times more transistors than before. And their application in skin-like Braille reading sensor arrays is more sensitive than human fingertips.

Performance leap, breaking records

In general, flexible electronics have the potential to be used in any application that requires interaction with soft materials, such as devices worn on or implanted in the body, including skin computers, soft robotics , and brain-computer interfaces.

However, traditional electronic devices are made of rigid materials such as silicon and metals. Although embedding them in plastic films can achieve a certain degree of flexibility, their stretchability is very limited, and their stretchability is usually only about 1% of their normal size. The innovation of the Stanford team is to develop "intrinsically stretchable" circuits.

They used high-purity semiconductor carbon nanotubes as channel materials, metal palladium-coated carbon nanotubes as electrodes, and highly conductive stretchable gallium-indium alloys as interconnects. By reducing limiting factors such as parasitic capacitance and interconnect resistance, the new transistor can maintain extremely high operating speeds even when stretched.

Specifically, the integrated circuit they created has an area of ​​about 28 square millimeters, integrates 1056 transistors and 528 logic gates, and operates at a frequency of more than 1 megahertz. This data far exceeds the previous best intrinsic stretchable circuit, which only integrates 54 transistors and 14 logic gates at most and operates at a frequency of only 330 Hz.

In addition, the field effect mobility of the new stretchable transistor (reflecting the speed of charge flow in the device) is as high as 20 square centimeters per second per volt on average, and will not be greatly reduced even in the stretched state, and the electrical performance is about 20 times higher than before. The driving current is 2 mA/micron, which is more than 40 times higher than the previous stretchable device, and is roughly the same as the most advanced flexible transistors that currently combine carbon nanotubes, metal oxides or polysilicon with plastic films.

The leap-forward improvement in performance is truly commendable and is expected to push flexible electronic products towards practical application.

Advanced applications, broad prospects

To demonstrate the practical application prospects of the new stretchable circuit, the research team built a tactile sensor array of only 8 square millimeters. This microarray has 2,500 sensors per square centimeter, which is more than 10 times the density of mechanical receptors on human fingertips and can accurately identify geometric shapes smaller than 1 millimeter.

It is reported that this array can be integrated into prostheses, orthotics and other devices to provide feedback information on pressure distribution, muscle activity and joint movement. It can also be used in human-computer interaction fields such as gesture recognition and motion capture.

Last words

Although the new stretchable circuits have outstanding performance, their large-scale production still faces many challenges.

From the perspective of materials and processes, although they are compatible with existing manufacturing processes, some adjustments and improvements are still needed, especially in the packaging technology of electronic components, which will directly affect the service life and reliability of the new circuits.

With the integration and development of emerging technologies such as artificial intelligence, 5G communications, the Internet of Things, and smart hardware, traditional electronic products are facing new challenges of intelligence. In this context, flexible electronic products are the ideal choice for the future smart lifestyle and have broad application prospects.

Flexible electronic products may become the main hardware of smart wearable devices. With highly deformable flexible circuits and sensor arrays, these wearable devices can accurately collect human motion, physiological and environmental data, providing intuitive experience for applications such as health monitoring, sports analysis, and virtual reality.

Moreover, traditional rigid robots have safety risks and lack of humanization, while soft robots with soft and flexible nature can avoid these problems. Relying on new stretchable circuits and intelligent materials, soft robots can achieve fine motion control and show their talents in home services, medical care and other scenarios. In addition, highly deformable flexible electronic products are also conducive to the innovation of human-computer interaction methods, such as full-body coated electronic skin, stretchable projection display, etc., which will inject new vitality into virtual reality and augmented reality experience.

In general, the integration of flexible electronic technology with artificial intelligence, robotics and other technologies will become an important support for the future intelligent society and help make the science fiction scene of human-machine symbiosis possible.