Tag Archives: Megan Scudellari

Solar-powered graphene skin for more feeling in your prosthetics

A March 23, 2017 news item on Nanowerk highlights research that could put feeling into a prosthetic limb,

A new way of harnessing the sun’s rays to power ‘synthetic skin’ could help to create advanced prosthetic limbs capable of returning the sense of touch to amputees.

Engineers from the University of Glasgow, who have previously developed an ‘electronic skin’ covering for prosthetic hands made from graphene, have found a way to use some of graphene’s remarkable physical properties to use energy from the sun to power the skin.

Graphene is a highly flexible form of graphite which, despite being just a single atom thick, is stronger than steel, electrically conductive, and transparent. It is graphene’s optical transparency, which allows around 98% of the light which strikes its surface to pass directly through it, which makes it ideal for gathering energy from the sun to generate power.

A March 23, 2017 University of Glasgow press release, which originated the news item, details more about the research,

Ravinder Dahiya

Dr Ravinder Dahiya

A new research paper, published today in the journal Advanced Functional Materials, describes how Dr Dahiya and colleagues from his Bendable Electronics and Sensing Technologies (BEST) group have integrated power-generating photovoltaic cells into their electronic skin for the first time.

Dr Dahiya, from the University of Glasgow’s School of Engineering, said: “Human skin is an incredibly complex system capable of detecting pressure, temperature and texture through an array of neural sensors which carry signals from the skin to the brain.

“My colleagues and I have already made significant steps in creating prosthetic prototypes which integrate synthetic skin and are capable of making very sensitive pressure measurements. Those measurements mean the prosthetic hand is capable of performing challenging tasks like properly gripping soft materials, which other prosthetics can struggle with. We are also using innovative 3D printing strategies to build more affordable sensitive prosthetic limbs, including the formation of a very active student club called ‘Helping Hands’.

“Skin capable of touch sensitivity also opens the possibility of creating robots capable of making better decisions about human safety. A robot working on a construction line, for example, is much less likely to accidentally injure a human if it can feel that a person has unexpectedly entered their area of movement and stop before an injury can occur.”

The new skin requires just 20 nanowatts of power per square centimetre, which is easily met even by the poorest-quality photovoltaic cells currently available on the market. And although currently energy generated by the skin’s photovoltaic cells cannot be stored, the team are already looking into ways to divert unused energy into batteries, allowing the energy to be used as and when it is required.

Dr Dahiya added: “The other next step for us is to further develop the power-generation technology which underpins this research and use it to power the motors which drive the prosthetic hand itself. This could allow the creation of an entirely energy-autonomous prosthetic limb.

“We’ve already made some encouraging progress in this direction and we’re looking forward to presenting those results soon. We are also exploring the possibility of building on these exciting results to develop wearable systems for affordable healthcare. In this direction, recently we also got small funds from Scottish Funding Council.”

For more information about this advance and others in the field of prosthetics you may want to check out Megan Scudellari’s March 30, 2017 article for the IEEE’s (Institute of Electrical and Electronics Engineers) Spectrum (Note: Links have been removed),

Cochlear implants can restore hearing to individuals with some types of hearing loss. Retinal implants are now on the market to restore sight to the blind. But there are no commercially available prosthetics that restore a sense of touch to those who have lost a limb.

Several products are in development, including this haptic system at Case Western Reserve University, which would enable upper-limb prosthetic users to, say, pluck a grape off a stem or pull a potato chip out of a bag. It sounds simple, but such tasks are virtually impossible without a sense of touch and pressure.

Now, a team at the University of Glasgow that previously developed a flexible ‘electronic skin’ capable of making sensitive pressure measurements, has figured out how to power their skin with sunlight. …

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

Energy-Autonomous, Flexible, and Transparent Tactile Skin by Carlos García Núñez, William Taube Navaraj, Emre O. Polat and Ravinder Dahiya. Advanced Functional Materials DOI: 10.1002/adfm.201606287 Version of Record online: 22 MAR 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Wetware, nanoelectronics and fuel cells

Some of the computer engineers I worked with years ago used to ‘jokingly’ refer to people as wetware putting us on a continuum with hardware, software, and firmware. Clearly they knew something I didn’t as it seems we’re getting closer to making that joke a reality with the term wetware expanding to include biological systems. Michael Berger in his July 19, 2011 Nanowerk Spotlight essay, Squishy electronics, takes a look at some of the developments in biocompatible electronics [Mar.7.12: duplicate paragraph removed from essay excerpt],

There is a physical and electrical disconnect between the world of electronics and the world of biology. Electronics tend to be rigid, operate using electrons, and are inherently two-dimensional. The brain, as a basis for comparison, is soft, operates using ions, and is three-dimensional. Researchers have therefore been looking to find different routes to create biocompatible devices that work well in wet environments like biological systems.

Berger goes on to highlight some research in North Carolina,

The device fabricated by the NC State team (that included graduate students Ju-Hee So and Hyung-Jun Koo, who also first-authored the paper [research team was led by Orlin Velev and Michael Dickey]) is composed primarily of water-based gels that are, in principle, compatible with biological species including cells, enzymes, proteins, and tissues and thus hold promise for interfacing electronics with biological systems. [emphasis mine]

The novelty of this work is the operating mechanism of the memory device combined with the fact that it is built entirely from materials with properties similar to Jell-O. The memristor-like devices are simple to fabricate and basically consist of two liquid-metal electrodes that sandwich a slab of hydrogel.

This line of work fits in nicely with ‘vampire’ batteries (my latest posting on this topic, July 18k 3011) which can, theoretically, run on blood. Coincidentally, The Scientist  published a June 23, 2011 article,  by Megan Scudellari which focuses on biological fuel cells that can run on bacteria,

This tiny biological fuel cell, the smallest of its kind with a total volume of just 0.3 microliters, was built using microfluidics and relies on bacteria to produce energy. Bacteria colonize the anode, the negatively charged end of the system, and through their natural metabolism produce electrons that flow to the cathode, creating a circuit. Together, the anode and cathode are only a few human hairs wide, but the tiny circuit generates a consistent flow of electricity.

An undated news item on the Carnegie Mellon University website offers this information,

Carnegie Mellon University’s Kelvin B. Gregory and Philip R. LeDuc have created the world’s smallest fuel cell — powered by bacteria.

Future versions of it could be used for self-powered sensing devices in remote locations where batteries are impractical, such as deep ocean or geological environments.

“We have developed a biological fuel cell which uses microbial electricity generation enabled by microfluidic flow control to produce power,” said Gregory, an assistant professor of civil and environmental engineering at CMU.

No bigger than a human hair, the fuel cell generates energy from the metabolism of bacteria on thin gold plates in micro-manufactured channels.

Those injunctions about not mixing liquids with electricity may soon seem a trifle old-fashioned.