Duke Research Blog

Following the people and events that make up the research community at Duke.

Category: Engineering Page 1 of 10

First-Year Students Designing Real-World Solutions

In the first week of fall semester, four first-year engineering students, Sean Burrell, Teya Evans, Adam Kramer, and Eloise Sinwell, had a brainstorming session to determine how to create a set of physical therapy stairs designed for children with disabilities. Their goal was to construct something that provided motivation through reward, had variable step height, and could physically support the students. 

Evans explained, “The one they were using before did not have handrails and the kids were feeling really unstable.”

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Teya Evans is pictured stepping on the staircase her team designed and built. With each step, the lightbox displays different colors.

The team was extremely successful and the staircase they designed met all of the goals set out by their client, physical therapists. It provided motivation through the multi-colored lightbox, included an additional smaller step that could be pulled out to adjust step height, had a handrail to physically support the students and could even be taken apart for easy transportation.

This is a part of the Engineering 101 course all Pratt students are required to take. Teams are paired with a real client and work together throughout the semester to design and create a deliverable solution to the problem they are presented with. At the end of the semester, they present their products at a poster presentation that I attended. It was pretty incredible to see what first-year undergraduates were able to create in just a few months.

The next poster I visited focused on designing a device to stabilize hand tremors. The team’s client, Kate, has Ataxia, a neurological disorder that causes her to have uncontrollable tremors in her arms and hands. She wanted a device that would enable her to use her iPad independently, because she currently needs a caregiver to stabilize her arm to use it. This team, Mohanapriya Cumaran, Richard Sheng, Jolie Mason, and Tess Foote, needed to design something that would allow Kate to access the entire screen while stabilizing tremors, being comfortable, easy to set up and durable.

The team was able to accomplish its task by developing a device that allowed Kate to stabilize her tremors by gripping a 3D printed handlebar. The handlebar was then attached to two rods that rested on springs allowing for vertical motion and a drawer slide allowing for horizontal motion.

“We had her [Kate] touch apps in all areas of the iPad and she could do it.” Foote said. “Future plans are to make it comfier.”

The team plans to improve the product by adding a foam grip to the handlebar, attaching a ball and socket joint for index finger support, and adding a waterproof layer to the wooden pieces in their design. 

The last project I visited created a “Fly Flipping Device.” The team, C. Fischer, E. Song, L. Tarman, and S. Gorbaly, were paired with the Mohamed Noor Lab in the Duke Biology Department as their client. 

Tarman explained, “We were asked to design a device that would expedite the process of transferring fruit flies from one vial to another.”

The Noor lab frequently uses fruit flies to study genetics and currently fly flipping has to be done by hand, which can take a lot of time. The goal was to increase the efficiency of lab experiments by creating a device that would last for more than a year, avoid damaging the vials or flies, was portable and fit within a desk space. 

The team came up with over 50 ideas on how to accomplish this task that they narrowed down to one that they would build. The product they created comprised of two arms made of PVC pipe resting on a wooden base. Attached to the arms were “sleeves” 3D printed to hold the vials containing flies. In order to efficiently flip the flies, one of the arms moves about the axis allowing for multiple vials to be flipped that the time it would normally take to flip one vial. The team was very successful and their creation will contribute to important genetic research.

The Fly Flipping Device

It was mind-blowing to see what first-year students were able to create in their first few months at Duke and I think it is a great concept to begin student education in engineering through a hands-on design process that allows them to develop a solution to a problem and take it from idea to implementation. I am excited about what else other EGR 101 students will design in the future.

By Anna Gotskind


How Do You Engineer a Microbial Community?

This is the first of several posts written by students at the North Carolina School of Science and Math as part of an elective about science communication with Dean Amy Sheck.

Claudia Gunsch, the Theodore Kennedy distinguished associate professor in the department of civil and environmental engineering, wants to know how to engineer a microbial community. An environmental engineer with a fascination for the world at the micro level, Gunsch takes a unique approach to solving the problem of environmental pollution: She looks to what’s already been done by nature.

Claudia Gunsch, Ph.D.

Gunsch and her team seek to harness the power of microbes to create living communities capable of degrading contamination in the environment.

“How can you engineer that microbial community so the organisms that degrade the pollutant become enriched?” she asks. “Or — if you’re thinking about dangerous pathogenic organisms — how do you engineer the microbial community so that those organisms become depressed in that particular environment?”

The first step, Gunsch says, is to figure out who’s there. What microbes make up a community? How do these organisms function? Who is doing what? Which organisms are interchangeable? Which prefer to live with one another, and which prefer not living with one another?

“Once we can really start building that kind of framework,” she says, “we can start engineering it for our particular purposes.”

Yet identifying the members of a microbial community is far more difficult than it may seem. Shallow databases coupled with vast variations in microbial communities leave Gunsch and her team with quite a challenge. Gunsch, however, remains optimistic.

Map of U.S. Superfund Sites (2013)

“The exciting part is that we have all these technologies where we can sequence all these samples,” she says. “As we become more sophisticated and more people do this type of research, we keep feeding all of this data into these databases. Then we will have more information and one day, we’ll be able to go out and take that sample and know exactly who’s there.”

“Right now, it’s in its infancy,” she says with a smile. “But in the long-term, I have no doubt we will get there.”

Gunsch is currently working on Duke’s Superfund Research Center designing bioremediation technologies for the degradation of polycyclic aromatic hydrocarbon (PAH) contamination. These pollutants are extremely difficult to break down due to their tendency to stick strongly onto soil and sediments. Gunsch and her team are searching for the right microbial community to break these compounds down — all by taking advantage of the innate capabilities of these microorganisms.

A photo montage from Dr. Gunsch’s lab page.

Step one, Gunsch says, has already been completed. She and her team have identified several different organisms capable of degrading PAHs. The next step, she explains, is assembling the microbial communities — taking these organisms and getting them to work together, sometimes even across kingdoms of life. Teamwork at the micro level.

The subsequent challenge, then, is figuring out how these organisms will survive and thrive in the environment they’re placed in, and which microbial seeds will best degrade the contamination when placed in the environment. This technique is known as “precision bioremediation” — similar to precision medicine, it involves finding the right solution in the right amounts to be the most effective in a certain scenario.

“In this particular case, we’re trying to figure out what the right cocktail of microbes we can add to an environment that will lead to the end result that is desired — in this case, PAH degradation,” Gunsch says.

Ultimately, the aim is to reduce pollution and restore ecological health to contaminated environments. A lofty goal, but one within sight. Yet Gunsch sees applications beyond work in the environment — all work dealing with microbes, she says, has the potential to be impacted by this research.

“If we understand how these organisms work together,” she says, “then we can advance our understanding of human health microbiomes as well.”

Post by Emily Yang, NCSSM 2021

Designing Tomorrow, One Healthcare Innovation at a Time

Imagine a live, health-focused version Shark Tank open to the public: presentations from real health professionals, presenting real innovations they developed to address real health care issues. And yes, there are real money awards at stake.

It’s the 2019 Duke Health Innovation Jam.

At ten minutes ‘til show time, people gather in small groups clothed in suits, business attire, and white coats. They chat in low voices. The hum of comfortable conversation buzzes through the room. The sixth floor of the Trent Semans Center is quite the setting. Three sides of the room are encapsulated in glass and you can easily see an expansive view of both Duke’s West and Medical campuses, as well as luscious green trees comprising parts of Duke’s Forest. Naturally, there is a glorious view of the Chapel, basked in sunlight.

This light finds its way into the room to shine on various research posters at the back displayed on a few rows of mobile walls. Though a few strays meander through the stationary arrangements – stopping to look more closely at particular findings – most people make their way into the room and find a seat as the minutes dwindle away. The hum grows and there is a bit of anticipatory energy among those readying themselves to present.

At three minutes after 10, the program director of the Duke Institute for Health Innovation, Suresh Balu, takes position at the front of the room, standing before the small stage at center that is surrounded by lots of TV monitors. No seat in the room is a bad one. Balu indicates that it is time to begin and the hum immediately dissipates. He explains the general format of the event: six pitches total, five minutes to present, eight minutes to answer questions from investors, a show-of-hand interest from investors, and transition to the next pitch, followed by deliberation and presentation of awards.

After a round of thanks, introduction of the emcee – Duke’s Chief of Cardiology, Dr. Manesh Patel – the curtains opened – figuratively – on Duke’s fifth annual Innovation Jam.

Groups presented on the problems they were addressing, their proposed innovations, and how the innovations worked. There was also information about getting products into the market, varying economic analysis, next steps or detailed goals for the projection of the projects, and analysis of the investment they are currently seeking and for what purposes.

The first group pitched an idea about patient-centric blood draw and suggest a device to plug into existing peripheral draws to reduce the frequent poking and prodding that hospital patients often experience during their hospital stay when blood is needed for lab tests. Next up was a group who designed an intelligent microscope for automated pathology that has a programmable system and uses machine learning to automate pathological blood analysis that is currently highly time consuming. Third at bat was a group that made a UV light bag to clean surgical drain bags that frequently become colonized with bacteria and are quite frankly “nasty” – according to the presenter.

Batting cleanup was PILVAS – Peripherally Inserted Left Ventricular Vent Anticoagulation System – which is a device that would be accessory to VA ECMO support to reduce thromboembolism and stroke that are risks of ECMO. Fifth was the ReadyView and ReadyLift, a laparoscopic tool set that is much cheaper than current laparoscopic tools and methods, and because of its ability to be used with any USB compatible laptop, it would increase access to laparoscopic surgery in countries that have a high need for it. Last, but not least, was an innovation that is the first synthetic biometric osteochondral graft for knee cartilage repair that hopes to improve knee osteoarthritis surgical care as the first hydrogel with the same mechanical properties of cartilage.

Following a quick ten-minute break for investors to huddle around and discuss who should win the awards – $15,000 for Best Innovation and $15,000 for Best Presentation – the winners were announced. Drumroll, please.

ReadyView won Best Presentation and the synthetic osteochondral graft won Best Innovation. A pair of representatives from Microsoft were also in attendance – a first for the Innovation Jam – and awarded SalineAI, the group who designed the intelligent microscope with an independent award package.

Patel, the emcee, says we are in the midst of a fourth industrial revolution.

“What is the biggest cinema in the world?” Patel asked. “Netflix,” he says. Industries are reimagining themselves and healthcare is no exception.

What is the best healthcare system of the future going to look like? Of course, we really don’t know, but there are certainly people who are already doing more than just think about it.

Science in haiku: // Interdisciplinary // Student poetry

On Friday, August 2, ten weeks of research by Data+ and Code+ students wrapped up with a poster session in Gross Hall where they flaunted their newly created posters, websites and apps. But they weren’t expecting to flaunt their poetry skills, too! 

Data+ is one of the Rhodes Information Initiative programs at Duke. This summer, 83 students addressed 27 projects addressing issues in health, public policy, environment and energy, history, culture, and more. The Duke Research Blog thought we ought to test these interdisciplinary students’ mettle with a challenge: Transforming research into haiku.

Which haiku is your
favorite? See all of their
finished work below!

Eric Zhang (group members Xiaoqiao Xing and Micalyn Struble not pictured) in “Neuroscience in the Courtroom”
Maria Henriquez and Jake Sumner on “Using Machine Learning to Predict Lower Extremity Musculoskeletal Injury Risk for Student Athletes”
Samantha Miezio, Ellis Ackerman, and Rodrigo Aruajo in “Durham Evictions: A snapshot of costs, locations, and impacts”
Nikhil Kaul, Elise Xia, and Mikaela Johnson on “Invisible Adaptations”
Karen Jin, Katherine Cottrell, and Vincent Wang in “Data-driven approaches to illuminate the responses of lakes to multiple stressors”.

By Vanessa Moss

Meet Dr. Sandra K. Johnson, Engineering “Hidden Figure”

When Dr. Sandra K. Johnson first tried her hand at electrical engineering during a summer institute in high school, she knew that she was born to be an electrical engineer. Now, as the first African-American woman to receive a Ph.D. in computer engineering in the United States, Johnson visited Duke to share her story as a “hidden figure” and inspire not just black women, but all students not to be discouraged by obstacles they may face in pursuit of their passion.

Though she did discuss her achievements, Johnson’s talk also made it clear that more than successes, it was the opposition she faced that most motivated her to persevere in electrical engineering. While pursuing a Master’s degree at Stanford, she met Dr. William Shockley, who in his free time was conducting research he believed would prove that African Americans were intellectually inferior to other races. Johnson had originally been planning on just finishing her program with a Master’s and then going into the workforce, but after hearing what this man was trying to prove, she decided she would prove to him that she was capable of doing anything that the non-black students in the same program could do. She finished the program with a Ph.D. in electrical engineering. She continued to make this declaration to anyone who didn’t believe she was capable: “before I leave this place, I will make a believer out of you.”

Dr. Johnson is the founder, CTO and CEO of Global Mobile Finance, Inc., a finance and tech startup based in Research Triangle Park, NC. Photo from BlackComputeHER.

While mapping out her own path to pursuing her goals, Johnson also firmly believed in making the path easier for other black people pursuing advanced degrees. When asked what the current generation of students could be doing to help themselves, she said to find mentors and to mentor others. Johnson shared an anecdote of sitting in a lab at Stanford waiting to begin an experiment when a man walked up to her and said she was in the wrong place. After talking to him for several minutes and showing him that she knew even more about the subject than he did and was in the right place, she told him that the next time someone who looked like her walked into the lab, not to be so sure of himself. Johnson went on to become an IBM Fellow, an IEEE Fellow, and a member of the prestigious Academy of Electrical Engineers. At the end of her talk, Johnson discussed what she believes is the best way to expedite change — to have people of color as founders and CEOs of major corporations that have the power to increase minority representation in their workforce. This is what she intends to do with her own company, Global Mobile Finance, Inc. If her current track record is any indication, there is no doubt her company will become a major corporation in the years to come, opening more doors for black women and other minorities pursuing their passions.

Post by Victoria Priester

Cracking the Code on Credit Cards at Datathon 2018

Anyone who has ever tried to formulate and answer their own research question knows that it means entering uncharted waters. This past weekend the hundreds of students in Duke Datathon 2018 did just that, using only their computer science prowess and a splash of innovation.

Here’s how it worked: the students were provided three data sets by Credit Sesame, a free credit score estimator, and given eight hours to use their insight and computer science knowledge to interpret the data and create as much value for the company as they could. Along the way, Duke Undergraduate Machine Learning (DUML), the organization hosting the event, provided mentors and workshops to help the participants find direction and achieve their goals. 

Datathon participants attempting to derive meaning from the Credit Sesame Data

This year was the first such ‘Datathon’ event to take place at Duke. The event attracted big-name sponsors such as Google and Pinterest and was made possible by the DUML executive team, headed by co-presidents Rohith Kuditipudi and Shrey Gupta (to see a full list of event sponsors, click here).

DUML faculty advisor Dr. Rebecca Steorts said that even the planning of the event transcended disciplines: one of her undergraduate students and co-president of DUML, Shrey Gupta, found a way to utilize statistics to predict how many people would be attending. “It’s all about finding computational ways of combining disciplines to solve the problem,” Steorts said, and it’s very apparent that her students have taken this to heart.

The winning team (Jie Cai, Catie Grasse, Feroze Mohideen) presenting on how they can best gauge which customers are most “valuable” to Credit Sesame

After more than an hour of deliberations, the eight top teams were selected and five finalists were asked to present their findings to the judges. The winning team (Jie Cai, Catie Grasse, Feroze Mohideen) proposed a way to gauge which customers who create trial accounts are most likely to be profitable, by using a computer filtering program to predict likely customer engagement based on customer-supplied data and their interaction with the free trial. Other top teams discussed similar topics with different variations on how Credit Sesame might best create this profile to determine who the “valuable” customers are likely to be.

DUML hosts other events throughout the year to engage students such as their MLBytes Speaker Series and ECE Seminar Series. To learn more about Duke Undergraduate Machine Learning, click here.

by Rebecca Williamson

 

 

 

 

 

Drug Homing Method Helps Rethink Parkinson’s

The brain is the body’s most complex organ, and consequently the least understood. In fact, researchers like Michael Tadross, MD, PhD, wonder if the current research methods employed by neuroscientists are telling us as much as we think.

Michael Tadross is using novel approaches to tease out the causes of neuropsychiatric diseases at a cellular level.

Current methods such as gene editing and pharmacology can reveal how certain genes and drugs affect the cells in a given area of the brain, but they’re limited in that they don’t account for differences among different cell types. With his research, Tadross has tried to target specific cell types to better understand mechanisms that cause neuropsychiatric disorders.

To do this, Tadross developed a method to ensure a drug injected into a region of the brain will only affect specific cell types. Tadross genetically engineered the cell type of interest so that a special receptor protein, called HaloTag, is expressed at the cell membrane. Additionally, the drug of interest is altered so that it is tethered to the molecule that binds with the HaloTag receptor. By connecting the drug to the Halo-Tag ligand, and engineering only the cell type of interest to express the specific Halo-Tag receptor, Tadross effectively limited the cells affected by the drug to just one type. He calls this method “Drugs Acutely Restricted by Tethering,” or DART.

Tadross has been using the DART method to better understand the mechanisms underlying Parkinson’s disease. Parkinson’s is a neurological disease that affects a region of the brain called the striatum, causing tremors, slow movement, and rigid muscles, among other motor deficits.

Only cells expressing the HaloTag receptor can bind to the AMPA-repressing drug, ensuring virtually perfect cell-type specificity.

Patients with Parkinson’s show decreased levels of the neurotransmitter dopamine in the striatum. Consequently, treatments that involve restoring dopamine levels improve symptoms. For these reasons, Parkinson’s has long been regarded as a disease caused by a deficit in dopamine.

With his technique, Tadross is challenging this assumption. In addition to death of dopaminergic neurons, Parkinson’s is associated with an increase of the strength of synapses, or connections, between neurons that express AMPA receptors, which are the most common excitatory receptors in the brain.

In order to simulate the effects of Parkinson’s, Tadross and his team induced the death of dopaminergic neurons in the striatum of mice. As expected, the mice displayed significant motor impairments consistent with Parkinson’s. However, in addition to inducing the death of these neurons, Tadross engineered the AMPA-expressing cells to produce the Halo-Tag protein.

Tadross then treated the mice striatum with a common AMPA receptor blocker tethered to the Halo-Tag ligand. Amazingly, blocking the activity of these AMPA-expressing neurons, even in the absence of the dopaminergic neurons, reversed the effects of Parkinson’s so that the previously affected mice moved normally.

Tadross’s findings with the Parkinson’s mice exemplifies how little we know about cause and effect in the brain. The key to designing effective treatments for neuropsychiatric diseases, and possibly other diseases outside the nervous system, may be in teasing out the relationship of specific types of cells to symptoms and targeting the disease that way.

The ingenious work of researchers like Tadross will undoubtedly help bring us closer to understanding how the brain truly works.

Post by undergraduate blogger Sarah Haurin

Post by undergraduate blogger Sarah Haurin

 

Heating Up the Summer, 3D Style

While some students like to spend their summer recovering from a long year of school work, others are working diligently in the Innovation Co-Lab in the Telcom building on West Campus.

They’re working on the impacts of dust and particulate matter (PM) pollution on solar panel performance, and discovering new technologies that map out the 3D volume of the ocean.

The Co-Lab is one of three 3D printing labs located on campus. It allows students and faculty the opportunity to creatively explore research through the use of new and emerging technologies.

Third-year PhD candidate Michael Valerino said his long term research project focuses on how dust and air pollution impacts the performance of solar panels.

“I’ve been designing a low-cost prototype which will monitor the impact of dust and air pollution on solar panels,” said Valerino. “The device is going to be used to monitor the impacts of dust and particulate matter (PM) pollution on solar panel performance. This processis known as soiling. This is going to be a low-cost alternative (~$200 ) to other monitoring options that are at least $5,000.”

Most of the 3D printers come with standard Polylactic acid (PLA) material for printing. However, because his first prototype completely melted in India’s heat, Valerino decided to switch to black carbon fiber and infused nylon.

“It really is a good fit for what I want to do,” he said. “These low-cost prototypes will be deployed in China, India, and the Arabian Peninsula to study global soiling impacts.”

In a step-by-step process, he applied acid-free glue to the base plate that holds the black carbon fiber and infused nylon. He then placed the glass plate into the printer and closely examined how the thick carbon fiber holds his project together.

Michael Bergin, a professor of civil and environmental engineering professor at Duke collaborated with the Indian Institute of Technology-Gandhinagar and the University of Wisconsin last summer to work on a study about soiling.

The study indicated that there was a decrease in solar energy as the panels became dirtier over time. The solar cells jumped 50 percent in efficiency after being cleaned for the first time in several weeks. Valerino’s device will be used to expand Bergin’s work.

As Valerino tackles his project, Duke student volunteers and high school interns are in another part of the Co-Lab developing technology to map the ocean floor.

The Blue Devil Ocean Engineering team will be competing in the Shell Ocean Discovery XPRIZE, a global technology competition challenging teams to advance deep-sea technologies for autonomous, fast and high-resolution ocean exploration. (Their mentor, Martin Brooke, was recently featured on Science Friday.)

The team is developing large, highly redundant carbon drones that are eight feet across. The drones will fly over the ocean and drop pods into the water that will sink to collect sonar data.

Tyler Bletsch, a professor of the practice in electrical and computer engineering, is working alongside the team. He describes the team as having the most creative approach in the competition.

“We have many parts of this working, but this summer is really when it needs to come together,” Bletsch said. “Last year, we made it through round one of the competition and secured $100,000 for the university. We’re now using that money for the final phase of the competition.”

The final phase of the competition is scheduled to be held fall 2018.
Though campus is slow this summer, the Innovation Co-Lab is keeping busy. You can keep up-to-date with their latest projects here.

Post by Alexis Owens

 

Artificial Intelligence Knows How You Feel

Ever wondered how Siri works? Afraid that super smart robots might take over the world soon?

On April 3rd researchers from Duke, NCSU and UNC came together for Triangle Machine Learning Day to provoke everyone’s curiosities about the complex field that is Artificial Intelligence. A.I. is an overarching term for smart technologies, ranging from self-driving cars to targeted advertising. We can arrive at artificial intelligence through what’s known as “machine learning.” Instead of explicitly programming a machine with the basic capabilities we want it to have, we can make it so that its code is flexible and adapts based on information it’s presented with. Its knowledge grows as a result of training it. In other words, we’re teaching a computer to learn.

Matthew Philips is working with Kitware to get computers to “see,” also known as “machine vision.” By providing thousands and thousands of images, a computer with the right coding can learn to actually make sense of what an image is beyond different colored pixels.

Machine vision has numerous applications. An effective way to search satellite imagery for arbitrary objects could be huge in the advancement of space technology – a satellite could potentially identify obscure objects or potential lifeforms that stick out in those images. This is something we as humans can’t do ourselves just because of the sheer amount of data there is to go through. Similarly, we could teach a machine to identify cancerous or malignant cells in an image, thus giving us a quick diagnosis if someone is at risk of developing a disease.

The problem is, how do you teach a computer to see? Machines don’t easily understand things like similarity, depth or orientation — things that we as humans do automatically without even thinking about. That’s exactly the type of problem Kitware has been tackling.

One hugely successful piece of Artificial Intelligence you may be familiar with is IBM’s Watson. Labeled as “A.I. for professionals,” Watson was featured on Sixty Minutes and even played Jeopardy on live television. Watson has visual recognition capabilities, can work as a translator, and can even understand things like tone, personality or emotional state. And obviously it can answer crazy hard questions. What’s even cooler is that it doesn’t matter how you ask the question – Watson will know what you mean. Watson is basically Siri on steroids, and the world got a taste of its power after watching it smoke its competitors on Jeopardy. However, Watson is not to be thought of as a physical supercomputer. It is a collection of technologies that can be used in many different ways, depending on how you train it. This is what makes Watson so astounding – through machine learning, its knowledge can adapt to the context it’s being used in.

Source: CBS News.

IBM has been able to develop such a powerful tool thanks to data. Stacy Joines from IBM noted, “Data has transformed every industry, profession, and domain.” From our smart phones to fitness devices, data is being collected about us as we speak (see: digital footprint). While it’s definitely pretty scary, the point is that a lot of data is out there. The more data you feed Watson, the smarter it is. IBM has utilized this abundance of data combined with machine learning to produce some of the most sophisticated AI out there.

Sure, it’s a little creepy how much data is being collected on us. Sure, there are tons of movies and theories out there about how intelligent robots in the future will outsmart humans and take over. But A.I. isn’t a thing to be scared of. It’s a beautiful creation that surpasses all capabilities even the most advanced purely programmable model has. It’s joining the health care system to save lives, advising businesses and could potentially find a new inhabitable planet. What we choose to do with A.I. is entirely up to us.

Post by Will Sheehan

Will Sheehan

Stretchable, Twistable Wires for Wearable Electronics

A new conductive “felt” carries electricity even when twisted, bent and stretched. Credit: Matthew Catenacci

The exercise-tracking power of a Fitbit may soon jump from your wrist and into your clothing.

Researchers are seeking to embed electronics such as fitness trackers and health monitors into our shirts, hats, and shoes. But no one wants stiff copper wires or silicon transistors deforming their clothing or poking into their skin.

Scientists in Benjamin Wiley’s lab at Duke have created new conductive “felt” that can be easily patterned onto fabrics to create flexible wires. The felt, composed of silver-coated copper nanowires and silicon rubber, carries electricity even when bent, stretched and twisted, over and over again.

“We wanted to create wiring that is stretchable on the body,” said Matthew Catenacci, a graduate student in Wiley’s group.

The conductive felt is made of stacks of interwoven silver-coated copper nanotubes filled with a stretchable silicone rubber (left). When stretched, felt made from more pliable rubber is more resilient to small tears and holes than felts made of stiffer rubber (middle). These tears can be seen in small cavities in the felt (right). Credit: Matthew Catenacci

To create a flexible wire, the team first sucks a solution of copper nanowires and water through a stencil, creating a stack of interwoven nanowires in the desired shape. The material is similar to the interwoven fibers that comprise fabric felt, but on a much smaller scale, said Wiley, an associate professor of chemistry at Duke.

“The way I think about the wires are like tiny sticks of uncooked spaghetti,” Wiley said. “The water passes through, and then you end up with this pile of sticks with a high porosity.”

The interwoven nanowires are heated to 300 F to melt the contacts together, and then silicone rubber is added to fill in the gaps between the wires.

To show the pliability of their new material, Catenacci patterned the nanowire felt into a variety of squiggly, snaking patterns. Stretching and twisting the wires up to 300 times did not degrade the conductivity.

The material maintains its conductivity when twisted and stretched. Credit: Matthew Catenacci

“On a larger scale you could take a whole shirt, put it over a vacuum filter, and with a stencil you could create whatever wire pattern you want,” Catenacci said. “After you add the silicone, so you will just have a patch of fabric that is able to stretch.”

Their felt is not the first conductive material that displays the agility of a gymnast. Flexible wires made of silver microflakes also exhibit this unique set of properties. But the new material has the best performance of any other material so far, and at a much lower cost.

“This material retains its conductivity after stretching better than any other material with this high of an initial conductivity. That is what separates it,” Wiley said.

Stretchable Conductive Composites from Cu-Ag Nanowire Felt,” Matthew J. Catenacci, Christopher Reyes, Mutya A. Cruz and Benjamin J. Wiley. ACS Nano, March 14, 2018. DOI: 10.1021/acsnano.8b00887

Post by Kara Manke

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