Tag Archives: electronic tattoo

Nanotechnology-enabled electronic tattoo from Tel Aviv University (Israel)

This is the first stick-on, nanotechnology-enabled tattoo I’ve seen that’s designed for the face. From a July 11, 2016 news item on ScienceDaily,

A new temporary “electronic tattoo” developed by Tel Aviv University [TAU] that can measure the activity of muscle and nerve cells researchers is poised to revolutionize medicine, rehabilitation, and even business and marketing research.

A July 11, 2016 American Friends of Tel Aviv University news release (also on EurekAlert), which originated the news item, provides more detail (Note: Some formatting has been changed),

The tattoo consists of a carbon electrode, an adhesive surface that attaches to the skin, and a nanotechnology-based conductive polymer coating that enhances the electrode’s performance. It records a strong, steady signal for hours on end without irritating the skin.

The electrode, developed by Prof. Yael Hanein, head of TAU’s Center for Nanoscience and Nanotechnology, may improve the therapeutic restoration of damaged nerves and tissue — and may even lead to new insights into our emotional life.

Prof. Hanein’s research was published last month in Scientific Reports and presented at an international nanomedicine program held at TAU.

“Stick it on and forget about it”

One major application of the new electrode is the mapping of emotion by monitoring facial expressions through electric signals received from facial muscles. “The ability to identify and map people’s emotions has many potential uses,” said Prof. Hanein. “Advertisers, pollsters, media professionals, and others — all want to test people’s reactions to various products and situations. Today, with no accurate scientific tools available, they rely mostly on inevitably subjective questionnaires.

“Researchers worldwide are trying to develop methods for mapping emotions by analyzing facial expressions, mostly via photos and smart software,” Prof. Hanein continued. “But our skin electrode provides a more direct and convenient solution.”

The device was first developed as an alternative to electromyography, a test that assesses the health of muscles and nerve cells. It’s an uncomfortable and unpleasant medical procedure that requires patients to lie sedentary in the lab for hours on end. Often a needle is stuck into muscle tissue to record its electrical activity, or patients are swabbed with a cold, sticky gel and attached to unwieldy surface electrodes.

“Our tattoo permits patients to carry on with their daily routines, while the electrode monitors their muscle and nerve activity,” said Prof. Hanein. “The idea is: stick it on and forget about it.”

Applications for rehabilitation and more

According to Prof. Hanein, the new skin electrode has other important therapeutic applications. The tattoo will be used to monitor the muscle activity of patients with neurodegenerative diseases in a study at Tel Aviv Medical Center.

“But that’s not all,” said Prof. Hanein. “The physiological data measured in specific muscles may be used in the future to indicate the alertness of drivers on the road; patients in rehabilitation following stroke or brain injury may utilize the ‘tattoo’ to improve muscle control; and amputees may employ it to move artificial limbs with remaining muscles.”

As it often is, the funding sources prove to be interesting (from the news release),

The electrode is the product of a European Research Council (ERC) project and received support from the BSMT Consortium of Israel’s Ministry of Economy.

The involvement of the European Research Council underlines the very close relationship Israel has to the European Union even though it is not an official member.

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

Temporary-tattoo for long-term high fidelity biopotential recordings by Lilach Bareket, Lilah Inzelberg, David Rand, Moshe David-Pur, David Rabinovich, Barak Brandes & Yael Hanein. Scientific Reports 6, Article number: 25727 (2016)  doi:10.1038/srep25727 Published online: 12 May 2016

This paper is open access.

A tattoo that’s a biobattery and a sensor?

It’s going to be an American Chemical Society (ACS) 248th meeting kind of week as yet another interesting piece of scientific research is bruited (spread) about the internet. This time it’s all about sweat, exercise, and biobatteries. From an Aug. 13, 2014 news item on Nanowerk,

In the future, working up a sweat by exercising may not only be good for your health, but it could also power your small electronic devices. Researchers will report today that they have designed a sensor in the form of a temporary tattoo that can both monitor a person’s progress during exercise and produce power from their perspiration.

An Aug. 13, 2014 ACS news release on EurekAlert, which originated the news item, describes the inspiration (as opposed to perspiration) for this technology,

The device works by detecting and responding to lactate, which is naturally present in sweat. “Lactate is a very important indicator of how you are doing during exercise,” says Wenzhao Jia, Ph.D.

In general, the more intense the exercise, the more lactate the body produces. During strenuous physical activity, the body needs to generate more energy, so it activates a process called glycolysis. Glycolysis produces energy and lactate, the latter of which scientists can detect in the blood.

Professional athletes monitor their lactate levels during performance testing as a way to evaluate their fitness and training program. In addition, doctors measure lactate during exercise testing of patients for conditions marked by abnormally high lactate levels, such as heart or lung disease. Currently, lactate testing is inconvenient and intrusive because blood samples must be collected from the person at different times during the exercise regime and then analyzed.

The news release goes on to describe the research process which resulted in a temporary tattoo that could be used to power small scale electronics,

Jia, a postdoctoral student in the lab of Joseph Wang, D.Sc., at the University of California San Diego, and her colleagues developed a faster, easier and more comfortable way to measure lactate during exercise. They imprinted a flexible lactate sensor onto temporary tattoo paper. The sensor contained an enzyme that strips electrons from lactate, generating a weak electrical current. The researchers applied the tattoo to the upper arms of 10 healthy volunteers. Then the team measured the electrical current produced as the volunteers exercised at increasing resistance levels on a stationary bicycle for 30 minutes. In this way, they could continuously monitor sweat lactate levels over time and with changes in exercise intensity.

The team then went a step further, building on these findings to make a sweat-powered biobattery. Batteries produce energy by passing current, in the form of electrons, from an anode to a cathode. In this case, the anode contained the enzyme that removes electrons from lactate, and the cathode contained a molecule that accepts the electrons.

When 15 volunteers wore the tattoo biobatteries while exercising on a stationary bike, they produced different amounts of power. Interestingly, people who were less fit (exercising fewer than once a week) produced more power than those who were moderately fit (exercising one to three times per week). Enthusiasts who worked out more than three times per week produced the least amount of power. The researchers say that this is probably because the less-fit people became fatigued sooner, causing glycolysis to kick in earlier, forming more lactate. The maximum amount of energy produced by a person in the low-fitness group was 70 microWatts per cm2 of skin.

“The current produced is not that high, but we are working on enhancing it so that eventually we could power some small electronic devices,” Jia says. “Right now, we can get a maximum of 70 microWatts per cm2, but our electrodes are only 2 by 3 millimeters in size and generate about 4 microWatts — a bit small to generate enough power to run a watch, for example, which requires at least 10 microWatts. So besides working to get higher power, we also need to leverage electronics to store the generated current and make it sufficient for these requirements.”

Biobatteries offer certain advantages over conventional batteries: They recharge more quickly, use renewable energy sources (in this case, sweat), and are safer because they do not explode or leak toxic chemicals.

“These represent the first examples of epidermal electrochemical biosensing and biofuel cells that could potentially be used for a wide range of future applications,” Wang says.

The ACS has made a video about this work available,

It seems to me this tattoo battery could be used as a self-powered monitoring device in a medical application for heart or lung disease.

E-tattoo without the nanotech

John Rogers and his team at the University of Illinois and a colleague’s (Yonggang Huang) team at Northwestern University have devised an ‘electronic tattoo’ (a soft, stick-on patch) made up from materials that anyone can purchase off-the-shelf. Rogers is known for his work with nanomaterials (my Aug. 10, 2012 posting titled ‘Surgery with fingertip control‘ mentioned a silicon nanomembrane that can be fitted onto the fingertips for possible use in surgical procedures) and with electronics (my Aug. 12, 2011 posting titled: ‘Electronic tattoos‘ mentioned his earlier attempts at developing e-tattoos).

This latest effort from Rogers and his multi-university team is mentioned in an April 4, 2014 article by Mark Wilson for Fast Company,

About a year ago, University of Illinois researcher John Rogers revealed a pretty amazing creation: a circuit that, rather than living on an inflexible board, could stick to and move with someone’s skin just like an ink stamp. But like any early research, it was mostly a proof-of-concept, and it would require relatively expensive, custom-printed electronics to work.

Today, Rogers, in conjunction with Northwestern University’s Yonggang Huang, has published details on version 2.0 in Science, revealing that this once-esoteric project has more immediate, mass market appeal.

… It means that you could create a wearable electronic that’s one-part special sticky circuit board, every other part whatever-the-hell-you-manufactured-in-China. This flexible circuit could accommodate a stock battery, an accelerometer, a Wi-Fi chip, and a Bluetooth circuitry, for instance, all living on your skin rather than inside your iPhone. And as an added bonus, it would be relatively cheap.

A University of Illinois April ?, 2014 news release describes Rogers, his multi-university team, and their current (pun intended) e-tattoo,

Engineers at the University of Illinois at Urbana-Champaign and Northwestern University have demonstrated thin, soft stick-on patches that stretch and move with the skin and incorporate commercial, off-the-shelf chip-based electronics for sophisticated wireless health monitoring.

The patches stick to the skin like a temporary tattoo and incorporate a unique microfluidic construction with wires folded like origami to allow the patch to bend and flex without being constrained by the rigid electronics components. The patches could be used for everyday health tracking – wirelessly sending updates to your cellphone or computer – and could revolutionize clinical monitoring such as EKG and EEG testing – no bulky wires, pads or tape needed.

“We designed this device to monitor human health 24/7, but without interfering with a person’s daily activity,” said Yonggang Huang, the Northwestern University professor who co-led the work with Illinois professor John A. Rogers. “It is as soft as human skin and can move with your body, but at the same time it has many different monitoring functions. What is very important about this device is it is wirelessly powered and can send high-quality data about the human body to a computer, in real time.”

The researchers did a side-by-side comparison with traditional EKG and EEG monitors and found the wireless patch performed equally to conventional sensors, while being significantly more comfortable for patients. Such a distinction is crucial for long-term monitoring, situations such as stress tests or sleep studies when the outcome depends on the patient’s ability to move and behave naturally, or for patients with fragile skin such as premature newborns.

Rogers’ group at Illinois previously demonstrated skin electronics made of very tiny, ultrathin, specially designed and printed components. While those also offer high-performance monitoring, the ability to incorporate readily available chip-based components provides many important, complementary capabilities in engineering design, at very low cost.

“Our original epidermal devices exploited specialized device geometries – super thin, structured in certain ways,” Rogers said. “But chip-scale devices, batteries, capacitors and other components must be re-formulated for these platforms. There’s a lot of value in complementing this specialized strategy with our new concepts in microfluidics and origami interconnects to enable compatibility with commercial off-the-shelf parts for accelerated development, reduced costs and expanded options in device types.”

The multi-university team turned to soft microfluidic designs to address the challenge of integrating relatively big, bulky chips with the soft, elastic base of the patch. The patch is constructed of a thin elastic envelope filled with fluid. The chip components are suspended on tiny raised support points, bonding them to the underlying patch but allowing the patch to stretch and move.

One of the biggest engineering feats of the patch is the design of the tiny, squiggly wires connecting the electronics components – radios, power inductors, sensors and more. The serpentine-shaped wires are folded like origami, so that no matter which way the patch bends, twists or stretches, the wires can unfold in any direction to accommodate the motion. Since the wires stretch, the chips don’t have to.

Skin-mounted devices could give those interested in fitness tracking a more complete and accurate picture of their activity level.

“When you measure motion on a wristwatch type device, your body is not very accurately or reliably coupled to the device,” said Rogers, a Swanlund Professor of Materials Science and Engineering at the U. of I. “Relative motion causes a lot of background noise. If you have these skin-mounted devices and an ability to locate them on multiple parts of the body, you can get a much deeper and richer set of information than would be possible with devices that are not well coupled with the skin. And that’s just the beginning of the rich range of accurate measurements relevant to physiological health that are possible when you are softly and intimately integrated onto the skin.”

The researchers hope that their sophisticated, integrated sensing systems could not only monitor health but also could help identify problems before the patient may be aware. For example, according to Rogers, data analysis could detect motions associated with Parkinson’s disease at its onset.

“The application of stretchable electronics to medicine has a lot of potential,” Huang said. “If we can continuously monitor our health with a comfortable, small device that attaches to our skin, it could be possible to catch health conditions before experiencing pain, discomfort and illness.”

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

Soft Microfluidic Assemblies of Sensors, Circuits, and Radios for the Skin by Sheng Xu, Yihui Zhang, Lin Jia, Kyle E. Mathewson, Kyung-In Jang, Jeonghyun Kim, Haoran Fu, Xian Huang, Pranav Chava, Renhan Wang, Sanat Bhole, Lizhe Wang, Yoon Joo Na, Yue Guan, Matthew Flavin, Zheshen Han, Yonggang Huang, & John A. Rogers. Science 4 April 2014: Vol. 344 no. 6179 pp. 70-74 DOI: 10.1126/science.1250169

This paper is behind a paywall.