Tag Archives: Yuta Dobashi

Wearable screen (flexible display) from the University of British Columbia (UBC)

If I read this correctly, the big selling point for UBC’s flexible, wearable display screen is energy efficiency. From a July 10, 2023 University of British Columbia (UBC) news release on EurekAlert,

Imagine a wearable patch that tracks your vital signs through changes in the colour display, or shipping labels that light up to indicate changes in temperature or sterility of food items.

These are among the potential uses for a new flexible display created by UBC researchers and announced recently in ACS Applied Materials and Interfaces.

“This device is capable of fast, realtime and reversible colour change,” says researcher Claire Preston, who developed the device as part of her master’s in electrical and computer engineering at UBC. “It can stretch up to 30 per cent without losing performance. It uses a colour-changing technology that can be used for visual monitoring. And it is relatively cheap to manufacture.”

Previous attempts at creating stretchable displays have involved complex designs and materials, limiting their stretchability and optical quality. In this new research, scientists leaned on electrochromic displays—which are able to reversibly change colour, while requiring low power consumption—to overcome these limitations. [emphasis mine]

“We used PEDOT:PSS, an electrochromic material that consists of a conductive polymer combined with an ionic liquid, resulting in a stretchable electrode that acts as both the electrochromic element and the ion storage layer. This simplifies the device’s architecture and eliminates the need for a separate stretchable conductor,” says Ms. Preston.

The display is transparent and feels like a stiff rubber band. To support the thin layers of PEDOT and allow them to elongate without breaking, the team added a solid polymer electrolyte and a stretchable encapsulation material called styrene-ethylene-butylene-styrene (SEBS).

“The potential uses for this stretchable display are significant. It could be integrated into wearable devices for biometric monitoring, allowing for real-time visual feedback on vital signs. The displays could also be used in robotic skin, enabling robots to display information and interact more intuitively with humans,” noted senior author Dr. John Madden, a professor of electrical and computer engineering who supervised the work.

Additionally, the low power consumption and cost-effectiveness of this technology make it attractive for use in disposable applications such as indicator patches for medical purposes or smart packaging labels for sensitive shipments. It could also be used to actively change the colour of jackets, hats and other garments.

“While there is need for more work to integrate this device into everyday devices, this breakthrough brings us one step closer to a future where flexible and stretchable displays are a common part of our daily lives,” Dr. Madden added.

Here’s a link to and a citation for the paper,

Intrinsically Stretchable Integrated Passive Matrix Electrochromic Display Using PEDOT:PSS Ionic Liquid Composite by Claire Preston, Yuta Dobashi, Ngoc Tan Nguyen, Mirza Saquib Sarwar, Daniel Jun, Cédric Plesse, Xavier Sallenave, Frédéric Vidal, Pierre-Henri Aubert, and John D. W. Madden. ACS Appl. Mater. Interfaces 2023, 15, 23, 28288–28299 DOI: https://doi.org/10.1021/acsami.3c02902 Publication Date: June 5, 2023 Copyright © 2023 The Authors. Published by American Chemical Society

This paper is open access.

Ionic skin for ‘smart’ skin

An April 28, 2022 University of British Columbia (UBC) news release (also on EurekAlert) announces a step forward in the attempt to create ‘smart’ skin, Note: Links have been removed,

In the quest to build smart skin that mimics the sensing capabilities of natural skin, ionic skins have shown significant advantages. They’re made of flexible, biocompatible hydrogels that use ions to carry an electrical charge. In contrast to smart skins made of plastics and metals, the hydrogels have the softness of natural skin. This offers a more natural feel to the prosthetic arm or robot hand they are mounted on, and makes them comfortable to wear.

These hydrogels can generate voltages when touched, but scientists did not clearly understand how — until a team of researchers at UBC devised a unique experiment, published today in Science.

“How hydrogel sensors work is they produce voltages and currents in reaction to stimuli, such as pressure or touch – what we are calling a piezoionic effect. But we didn’t know exactly how these voltages are produced,” said the study’s lead author Yuta Dobashi, who started the work as part of his master’s in biomedical engineering at UBC.

Working under the supervision of UBC researcher Dr. John Madden, Dobashi devised hydrogel sensors containing salts with positive and negative ions of different sizes. He and collaborators in UBC’s physics and chemistry departments applied magnetic fields to track precisely how the ions moved when pressure was applied to the sensor.

“When pressure is applied to the gel, that pressure spreads out the ions in the liquid at different speeds, creating an electrical signal. Positive ions, which tend to be smaller, move faster than larger, negative ions. This results in an uneven ion distribution which creates an electric field, which is what makes a piezoionic sensor work.”

The researchers say this new knowledge confirms that hydrogels work in a similar way to how humans detect pressure, which is also through moving ions in response to pressure, inspiring potential new applications for ionic skins.

“The obvious application is creating sensors that interact directly with cells and the nervous system, since the voltages, currents and response times are like those across cell membranes,” says Dr. Madden, an electrical and computer engineering professor in UBC’s faculty of applied science. “When we connect our sensor to a nerve, it produces a signal in the nerve. The nerve, in turn, activates muscle contraction.”

“You can imagine a prosthetic arm covered in an ionic skin. The skin senses an object through touch or pressure, conveys that information through the nerves to the brain, and the brain then activates the motors required to lift or hold the object. With further development of the sensor skin and interfaces with nerves, this bionic interface is conceivable.”

Another application is a soft hydrogel sensor worn on the skin that can monitor a patient’s vital signs while being totally unobtrusive and generating its own power.

Dobashi, who’s currently completing his PhD work at the University of Toronto, is keen to continue working on ionic technologies after he graduates.

“We can imagine a future where jelly-like ‘iontronics’ are used for body implants. Artificial joints can be implanted, without fear of rejection inside the human body. Ionic devices can be used as part of artificial knee cartilage, adding a smart sensing element.  A piezoionic gel implant might release drugs based on how much pressure it senses, for example.”

Dr. Madden added that the market for smart skins is estimated at $4.5 billion in 2019 and it continues to grow. “Smart skins can be integrated into clothing or placed directly on the skin, and ionic skins are one of the technologies that can further that growth.”

The research includes contributions from UBC chemistry PhD graduate Yael Petel and Carl Michal, UBC professor of physics, who used the interaction between strong magnetic fields and the nuclear spins of ions to track ion movements within the hydrogels. Cédric Plesse, Giao Nguyen and Frédéric Vidal at CY Cergy Paris University in France helped develop a new theory on how the charge and voltage are generated in the hydrogels.

Interview language(s): English (Dobashi, Madden), French (Plesse, Madden), Japanese (Dobashi)

Here’s a link to and a citation for the paper,

Piezoionic mechanoreceptors: Force-induced current generation in hydrogels by
Yuta Dobashi, Dickson Yao, Yael Petel, Tan Ngoc Nguyen, Mirza Saquib Sarwar, Yacine Thabet, Cliff L. W. Ng, Ettore Scabeni Glitz, Giao Tran Minh Nguyen, Cédric Plesse, Frédéric Vidal, Carl A. Michal and John D. W. Madden. Science • 28 Apr 2022 • Vol 376, Issue 6592 • pp. 502-507 • DOI: 10.1126/science.aaw1974

This paper is behind a paywall.