Nav: Home

A novel method for the fabrication of active-matrix 3-D pressure sensors

April 05, 2017

A recent study, affiliated with UNIST has created a three-dimensional, tactile sensor that could detect wide pressure ranges from human body weight to a finger touch. This new sensor with transparent features is capable of generating an electrical signal based on the sensed touch actions, also, consumes far less electricity than conventional pressure sensors.

The breakthrough comes from a research, conducted by Professor Jang-Ung Park of Materials Science and Engineering and his research team at UNIST. In the study, the research team presented a novel method of fabricating a transistor-type active-matrix pressure sensor using foldable substrates and air-dielectric layers.

Today, most transistors are created with silicon channel and silicon oxide-based dielectrics. However, these transistors have been found to be either lacking transparency or inflexible, which may hinder their utility in fabricating highly-integrated pressure sensor arrays and transparent pressure sensors.

In this regard, Professor Park's team decided to use highly-conductive and transparent graphene transistors with air-dielectric layers. The sensor can detect different types of touch-including swiping and tapping..

"Using air as the dielectric layer in graphene field-effect transistors (FETs) can significantly improve transistor performance due to the clean interface between graphene channel and air," says Professor Park. "The thickness of the air-dielectric layers is determined by the applied pressure. With that technology, it would be possible to detect pressure changes far more effectively."

A convantional touch panel, which may be included in a display device, reacts to the static electrical when pressure is applied to the monitor screen. With this method, the position on screen contacted by a finger, stylus, or other object can be easily detected using changes in pressure, but can not provide the intensity of pressure.

The research team placed graphene channel, metal nanowire electrodes, as well as an elastic body capable of trapping air on one side of the foldable substrate. Then they covered the other side of the substrate, like a lid and kept the air. In this transistor, the force pressing the elastic body is transferred to the air-dielectric layer and alters its thickness. Such changes in the thickness of the air-dielectric layer is converted into an electrical signal and transmitted via metal nanowires and the graphene channel, expressing both the position and the intensity of the pressure.

This is regarded as a promising technology as it enables the successful implementation of active-matrix pressure sensors. Moreover, when compared with the passive-matrix type, it consumes less power and has a faster response time.

It is possible to send and receive signals only by flowing electricity to the place where pressure is generated. The change in the thickness of the air dielectric layer is converted into an electrical signal to represent the position and intensity of the pressure. In addition, since all the substrates, channels, and electrode materials used in this process are all transparent, they can also be manufactured with invisible pressure sensors.

"This sensor is capable of simultaneously measuring anything from lower pressure (less than 10 kPa), such as gentle tapping to high pressure (above 2 MPa), such as human body weight," says Sangyoon Ji (Combined M.S./Ph.D. student of Materials Science and Engineering), the first co-author of the study. "It can be also applied to 3D touchscreen panels or smart running shoes that can analyze life patterns of people by measuring their weight distribution."

"This study not only solves the limitations of conventional pressure sensors, but also suggests the possibility to apply them to various fields by combining pressure sensor with other electronic devices such as display." says Professor Park.
-end-
The results of the study have been published in the April issue of the journal Nature Communications, a sister journal of the prestigious Nature. It has been supported by the Ministry of Science, ICT & Future Planning (MSIP) and the Ministry of Trade, Industry and Energy (MOTIE) of Korea through the National Research Foundation.

Journal Reference

Shin, S.-H. et al. "Integrated Arrays of Air-Dielectric Graphene Transistors as Transparent, Active-Matrix Pressure Sensors for Wide Pressure Ranges", Nat. Commun. 8, (2017).

Ulsan National Institute of Science and Technology(UNIST)

Related Transistors Articles:

Graphene transistor could mean computers that are 1,000 times faster
Transistors based on graphene ribbons could result in much faster, more efficient computers and other devices.
Engineer unveils new spin on future of transistors with novel design
An engineer with the Erik Jonsson School of Engineering and Computer Science at The University of Texas at Dallas has designed a novel computing system made solely from carbon that might one day replace the silicon transistors that power today's electronic devices.
Engaging diamond for next-era transistors
Most transistors are silicon-based and silicon technology has driven the computer revolution.
Researchers develop transistors that can switch between 2 stable energy states
Engineers are unveiling an upgrade to the transistor laser that could be used to boost computer processor speeds -- the formation of two stable energy states and the ability to switch between them quickly.
Flexible processors with atomically thin materials
The first fully functional microprocessor logic devices based on few-atom-thick layered materials have been demonstrated by researchers from the Graphene Flagship, working at TU Vienna in Austria, with promise for integrating computational power into everyday objects and surfaces
Graphene Flagship researches create thin film transistors printed with layered materials
Graphene Flagship researchers from AMBER at Trinity College Dublin have fabricated printed transistors consisting entirely of layered materials.
Carbon nanotubes self-assemble into tiny transistors
Carbon nanotubes can be used to make very small electronic devices, but they are difficult to handle.
Germanium outperforms silicon in energy efficient transistors with n- und p- conduction
NaMLab and cfaed reached an important breakthrough in the development of energy-efficient electronic circuits using transistors based on germanium.
A flexible transistor that conforms to skin
Researchers have created a stretchy transistor that can be elongated to twice its length with only minimal changes in its conductivity.
3-D solutions to energy savings in silicon power transistors
Tokyo Tech researchers demonstrate operation energy-savings in a low price silicon power transistor structure by scaling down in all three dimensions.

Related Transistors Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...