鈥淥ur digital technology operates through a series of electronic on-off switches that control the flow of current and voltage,鈥� said , a research scientist at the 天美影视传媒. 鈥淏ut our bodies operate on chemistry. In our brains, neurons propagate signals electrochemically, by moving ions 鈥� charged atoms or molecules 鈥� not electrons.鈥�

Implantable devices from pacemakers to glucose monitors rely on components that can speak both languages and bridge that gap. Among those components are OECTs 鈥� or organic electrochemical transistors 鈥� which allow current to flow in devices like implantable biosensors. But scientists long knew about a quirk of OECTs that no one could explain: When an OECT is switched on, there is a lag before current reaches the desired operational level. When switched off, there is no lag. Current drops almost immediately.

A UW-led study has solved this lagging mystery, and in the process paved the way to custom-tailored OECTs for a growing list of applications in biosensing, brain-inspired computation and beyond.

鈥淗ow fast you can switch a transistor is important for almost any application,鈥� said project leader , a UW professor of chemistry, chief scientist at the UW Clean Energy Institute and faculty member in the UW Molecular Engineering and Sciences Institute. 鈥淪cientists have recognized the unusual switching behavior of OECTs, but we never knew its cause 鈥� until now.鈥�

In a published April 17 in Nature Materials, Ginger鈥檚 team at the UW 鈥� along with Professor at the Okinawa Institute of Science and Technology in Japan and Professor at Zhejiang University in China 鈥� report that OECTs turn on via a two-step process, which causes the lag. But they appear to turn off through a simpler one-step process.

In principle, OECTs operate like transistors in electronics: When switched on, they allow the flow of electrical current. When switched off, they block it. But OECTs operate by coupling the flow of ions with the flow of electrons, which makes them interesting routes for interfacing with chemistry and biology.

The new study illuminates the two steps OECTs go through when switched on. First, a wavefront of ions races across the transistor. Then, more charge-bearing particles invade the transistor鈥檚 flexible structure, causing it to swell slightly and bringing current up to operational levels. In contrast, the team discovered that deactivation is a one-step process: Levels of charged chemicals simply drop uniformly across the transistor, quickly interrupting the flow of current.

Knowing the lag鈥檚 cause should help scientists design new generations of OECTs for a wider set of applications.

鈥淭here鈥檚 always been this drive in technology development to make components faster, more reliable and more efficient,鈥� Ginger said. 鈥淵et, the 鈥榬ules鈥� for how OECTs behave haven鈥檛 been well understood. A driving force in this work is to learn them and apply them to future research and development efforts.鈥�

Whether they reside within devices to measure blood glucose or brain activity, OECTs are largely made up of flexible, organic semiconducting polymers 鈥� repeating units of complex, carbon-rich compounds 鈥� and operate immersed in liquids containing salts and other chemicals. For this project, the team studied OECTs that change color in response to electrical charge. The polymer materials were synthesized by Luscombe鈥檚 team at the Okinawa Institute of Science and Technology and Li鈥檚 at Zhejiang University, and then fabricated into transistors by UW doctoral students Jiajie Guo and Shinya 鈥淓merson鈥� Chen, who are co-lead authors on the paper.

鈥淎 challenge in the materials design for OECTs lies in creating a substance that facilitates effective ion transport and retains electronic conductivity,鈥� said Luscombe, who is also a UW affiliate professor of chemistry and of materials science and engineering. 鈥淭he ion transport requires a flexible material, whereas ensuring high electronic conductivity typically necessitates a more rigid structure, posing a dilemma in the development of such materials.鈥�

Guo and Chen observed under a microscope 鈥� and recorded with a smartphone camera 鈥� precisely what happens when the custom-built OECTs are switched on and off. It showed clearly that a two-step chemical process lies at the heart of the OECT activation lag.

Past research, including by Ginger鈥檚 group at the UW, demonstrated that polymer structure, especially its flexibility, is important to how OECTs function. These devices operate in fluid-filled environments containing chemical salts and other biological compounds, which are more bulky compared to the electronic underpinnings of our digital devices.

The new study goes further by more directly linking OECT structure and performance. The team found that the degree of activation lag should vary based on what material the OECT is made of, such as whether its polymers are more ordered or more randomly arranged, according to Giridharagopal. Future research could explore how to reduce or lengthen the lag times, which for OECTs in the current study were fractions of a second.

鈥淒epending on the type of device you鈥檙e trying to build, you could tailor composition, fluid, salts, charge carriers and other parameters to suit your needs,鈥� said Giridharagopal.

OECTs aren鈥檛 just used in biosensing. They are also used to study nerve impulses in muscles, as well as forms of computing to create artificial neural networks and understand how our brains store and retrieve information. These widely divergent applications necessitate building new generations of OECTs with specialized features, including ramp-up and ramp-down times, according to Ginger.

鈥淣ow that we鈥檙e learning the steps needed to realize those applications, development can really accelerate,鈥� said Ginger.

Guo is now a postdoctoral researcher at the Lawrence Berkeley National Laboratory and Chen is now a scientist at Analog Devices. Other co-authors on the paper are , a former UW postdoctoral researcher in chemistry who is now an assistant professor at the University of Utah; Jonathan Onorato, a UW doctoral alum and scientist at Exponent; and Kangrong Yan and Ziqui Shen of Zhejiang University. The research was funded by the U.S. National Science Foundation, and polymers developed at Zhejiang University were funded by the National Science Foundation of China.

For more information contact Ginger at dginger@uw.edu, Luscombe at christine.luscombe@oist.jp and Giridharagopal at rgiri@uw.edu.

Seven scientists and engineers at the 天美影视传媒 have been elected to the Washington State Academy of Sciences, according to an July 15 by the academy. One-third of the 21 new members for 2020 hail from the UW.

The new members are lauded for 鈥渢heir outstanding record of scientific and technical achievement and their willingness to work on behalf of the academy to bring the best available science to bear on issues within the state of Washington.鈥� The academy鈥檚 current membership selected 17 of the new members, and four were chosen by virtue of their election to one of the .

New UW members who were elected by academy members are:

• , the Frank & Julie Jungers Dean of the College of Engineering and professor of bioengineering, 鈥渇or outstanding contributions to the design and application of microtechnologies to biomedical research, leadership in interdisciplinary research and education, and entrepreneurial excellence.鈥�
• , professor of chemistry and of materials science and engineering, 鈥渇or the development of controlled polymerization reactions for conjugated polymers, especially alkyl-thiophenes, for organic electronics applications.鈥澛燣uscombe is also a faculty member with the , the and the .
• , professor of Earth and space sciences, 鈥渇or fundamental contributions to geomorphology, for the elucidation of soils, rivers, and landscapes as underpinnings of ecological systems and human societies, and for reaching broad audiences through trade books on agriculture, microbes, creationism, and fisheries.鈥�
• Sue Moore, research scientist at the in the Department of Biology, 鈥渇or contributions to the understanding of Arctic marine ecosystems and pioneering the integration of Conventional Science and Indigenous Knowledge to yield better policy decisions.鈥�
• , professor of pharmacology, 鈥渇or exceptional contributions to the understanding of the molecular mechanisms by which ubiquitin ligases, as a new class of enzymes, control protein ubiquitination in human physiology and diseases, as well as plant growth and development.鈥�

UW members who were chosen by virtue of their election to one of the National Academies are:

• , professor of biostatistics and of epidemiology at the UW and a faculty member at the Fred Hutchinson Cancer Research Center, 鈥渇or pioneering work in the field of designing and analyzing vaccine studies, including studies of HIV vaccines and innovative use of mathematical and statistical methods to study infectious disease.鈥� Halloran was elected to the National Academy of Medicine in 2019.
• , professor emeritus of civil and environmental engineering, 鈥渇or contributions to geotechnical earthquake engineering, including liquefaction, seismic stability and seismic site response.鈥� Kramer was elected to the National Academy of Engineering in 2020.

New members are to be inducted at the annual members meeting, which is currently scheduled for September.

Plastic pollution is an increasingly present threat to marine life and one which can potentially impact your dinner table.聽

Oysters, and other economically valuable shellfish, filter their food from the water where they may also inadvertently capture tiny microplastics. The ingestion and accumulation of these microplastics can have detrimental effects on their health and may be passed to other animals, including humans, through the food chain.

In a recent interdisciplinary study, 天美影视传媒 researchers at the School of Aquatic and Fishery Sciences, Department of Chemistry and Department of Materials Science and Engineering used advanced methodologies to accurately identify and catalog microplastics in Pacific oysters from the Salish Sea. They have discovered that the abundance of tiny microplastic contaminants in these oysters is much lower than previously thought. The were published in January in the journal Science of the Total Environment.

鈥淯ntil now, not a lot of chemical analysis has been done on microplastics in oysters,鈥� said co-author , a UW doctoral student in chemistry. 鈥淭he microplastics that chemists have looked at in previous studies are slightly bigger and easy to visually recognize, but with oysters, the microplastics are much smaller and harder to identify.鈥�

In their study, the team sampled wild Pacific oysters harvested from Washington鈥檚 state parks throughout the Salish Sea. Using standard processing methods, the oysters鈥� tissue is dissolved and the remaining solution is passed through a filter. The filter collects all of the possible microplastic particles.

鈥淥bservation of filters is the method researchers have typically used, so if we had stopped there, we would have thought all the oysters had microplastics because small particles were present in most of the filters,鈥� said lead author , a UW postdoctoral researcher at the School of Aquatic and Fishery Sciences.聽聽

Martinelli鈥檚 initial observations under a dissecting microscope revealed what were thought to be high numbers of microplastics left behind in the testing filters, but when Phan further analyzed those filters with three advanced chemical identification techniques, they realized that most of what was left in the filters was not actually plastic.

鈥淲hen we’re characterizing plastics, or any polymers in chemistry in general, we have to use multiple techniques, and not every technique will give you a full picture. It’s half a picture or just part of the picture,鈥� said Phan. 鈥淲hen you put all those pictures and characterizations together, you can have a more complete understanding of what the composition or identities of these particles are.鈥�

During their analyses, the team realized that many of the particles were, in fact, shell fragments, minerals, salts and even fibers from the testing filters themselves. In the end, they found that only about 2% of the particles distilled from the oysters could be confirmed as plastics.聽

鈥淢ost people so far have not used the combination of techniques or instruments that we used,鈥� said Martinelli. 鈥淚t’s really easy to stop at the first part and say, 鈥極h, there’s a lot of particles here. They look like plastic. They must be plastic.鈥� But when you actually go deeper into the chemical composition, they might not be.鈥�

The number of plastic particles that the team found was relatively low compared to the total number of particles analyzed; however, they stress that while it appears Pacific oysters are not accumulating large amounts of plastic, they could not identify 40% of the particles observed due to technical limitations. The researchers also acknowledge that while using a combination of instruments is the most complete way to analyze these particles, access to the equipment, elevated costs and the extremely time-consuming nature of the work are limiting factors for widespread use.

As suspension feeders, oysters pull in water and the particles present in it when they inhale. Particles are then sorted in and out of the animal through their gills. Previous experiments have shown that when oysters are given microfibers or microbeads, they expel the majority of them either immediately or after a few hours. The hypothesis is that oysters鈥� gill anatomy and physiology might be the reason why the team did not see large amounts of plastic accumulation in their samples.

鈥淎 lot of this has to do with how the oysters process water through their gills and how they get rid of particles,鈥� said Martinelli. 鈥淚t doesn’t mean microplastics are not in the water, it means that the animals are better at expelling them.鈥澛�

In agreement with this, it has been suggested that suspension-feeding bivalves like oysters might not be good indicators of pollution in estuaries because they naturally expel microplastics instead of ingesting them, which is good news for consumers that like eating oysters.

Other co-authors are , a UW professor of materials science and engineering, and , a UW assistant professor of aquatic and fishery sciences.

This research was supported by NOAA-SK and the Royal Research Fund awarded to Padilla-Gami帽o. Part of this work was conducted at the Molecular Analysis Facility, a National Nanotechnology Coordinated Infrastructure site at the 天美影视传媒 supported in part by the National Science Foundation, the 天美影视传媒, the Molecular Engineering & Sciences Institute and the Clean Energy Institute, and the Washington Research Foundation.

For more information, contact Martinelli at julimar@uw.edu and Phan at samphan@uw.edu.

Grant number:聽 NNCI-1542101 (NSF)

The new center builds on the UW’s record of innovative, collaborative and cross-disciplinary research in the materials sciences, and on a legacy of timely institutional and state investments in materials research at the UW. Initial research will focus on nanocrystals and thin films 鈥� toward goals such as developing new materials for applications in clean energy, photonics and quantum computing.

“The primary goal of the UW MRSEC is to empower the next generation of science and engineering leaders,” said center director and UW chemistry professor . “This will involve engaging and supporting students and postdoctoral researchers 鈥� and giving them the research and educational experiences, training and cross-disciplinary mentorship that they will need to forge careers on the cutting edge of materials science.”

The center will embark on new research and training endeavors to:

• Pursue so-called “moonshot” projects, which are research endeavors with potentially high payoff, but are generally beyond the feasibility of smaller research grants awarded to individual professors.
• Implement new cross-disciplinary training and mentorship programs for doctoral students and postdoctoral researchers, including opportunities to conduct research with the center’s industrial and international partners, and with partners at and at other run by the U.S. Department of Energy.
• Broaden educational and research opportunities for UW students and researchers, including advanced training on new equipment purchased with center funds.
• Expand outreach and mentorship efforts to high school students from underrepresented minorities to encourage them to pursue science, technology, engineering and math (STEM) education as undergraduates.
• Implement comprehensive outreach efforts to recruit military veterans at the UW and at local community colleges into research and education for STEM careers.
• Provide support for additional doctoral and postdoctoral researchers.

The center’s inaugural team of 15 faculty come from a variety of disciplines across engineering and the physical sciences. In addition to their home departments in the College of Engineering and the College of Arts & Sciences, 10 are also faculty members in the CEI and 11 in the MolES. This diverse cohort reflects the center’s goal to foster novel and innovative collaborations across traditionally separate disciplines.

The center will make use of existing research and education space across the UW campus, including in the . The CEI and the MolES, both of which are headquartered in that building, will provide access to equipment for center research and training.

The center’s outreach activities 鈥� both within the UW and around the region 鈥� emphasize education and training for materials science careers. Each year it will host a program for students from around the country to conduct research with a UW faculty member during the summer. In addition, center scientists will mentor pre-college students from underrepresented minority groups, providing support and resources to help prepare them for college and encourage them to pursue STEM education. In an entirely new endeavor, the center also will set up programs to engage veterans in center research, very few of whom pursue STEM education and careers.

“With this NSF support, the center will bring new opportunities in STEM education to groups that are underrepresented in STEM careers,” said UW professor of materials science and engineering , who is the center’s executive director for education and outreach. “Programs like these are expanding access to science.”

The center will focus on two broad research areas, in nanocrystals and thin films.

The first goal, co-led by Gamelin and Luscombe and including eight initial faculty members, is to pursue new approaches to engineer defects in nanocrystals such as semiconductor quantum dots. Though “defects” often have a negative connotation, in materials science they are opportunities to create substances with novel and technologically attractive properties. Precisely targeted defects or impurities, for example, could 鈥� rather than heat up 鈥� when hit by a laser. These new materials could also lead to products such as solar-concentrating window films that absorb photons from sunlight and shunt them to photovoltaic cells for energy conversion.

The center’s other focus is the creation of new ultrathin semiconductor materials with unique properties. This team will include seven initial faculty, and is co-led by associate professor of physics and materials science and engineering and assistant professor of physics and electrical engineering . This research creates thin sheets of materials 鈥� often just one layer of atoms thick 鈥� and investigates the unique quantum-mechanical properties revealed when these sheets are layered together. These layered materials could form the basis of new for applications in clean energy, optoelectronics and other applications. In fact, using this approach, one UW team recently discovered a .

“We chose nanocrystals and ultrathin semiconductors because they promise to yield basic, fundamental and impactful discoveries in materials science,” said Gamelin. “And those advances will fuel new innovations and applications in growing industries 鈥� from quantum computing to clean energy.”

Gamelin, Xu and Fu 鈥� along with assistant professor of chemistry and electrical engineering professor 鈥� represented the UW team in Washington, D.C., during the final leg of the multi-stage competition for NSF-MRSEC support. Funding for the UW’s Molecular Engineering Materials Center began Sept. 1. The NSF supports 20 MRSECs across the nation, and the UW’s is one of only two on the West Coast.

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For more information, contact Gamelin at gamelin@chem.washington.edu or 206-685-0901.

On his weekly list are various speaking engagements, his class schedule, volunteer events, lab time, and meetings with the boards of his startup company and a nonprofit he heads.

But though Coven’s schedule looks frenzied and chaotic, his demeanor on a typical Tuesday afternoon is calm and collected. The 天美影视传媒 mechanical engineering undergraduate chats easily with a friend while entering yet another colored box in his online calendar.

For , 20, this is all about making the most of opportunities.

“Work hard, work smart and ask people for help,” Coven likes to tell others who ask about his motivation. “People who are successful spend hours, days, months and years perfecting their craft.”

From starting his own company 鈥� and recruiting 11 friends to join him 鈥� and running a successful nonprofit to doing research in the lab and taking a full course load, Coven is an expert schedule juggler. He also has managed to entirely fund his education by earning a number of scholarships, including the Costco Diversity Scholarship and the Washington State Opportunity Scholarship.

Coven last month got first place in the university category at the competition in Seattle for his five-minute speech about , his nonprofit that helps students secure scholarships by providing editing assistance and writing advice. UW bioengineering graduate student won second place at the pitch competition for his team’s idea for a stem cell bank.

Last year, Scholarship Junkies 鈥� a group of about 25 undergraduates, doctoral students, and young professional volunteers who successfully earned scholarships in the past 鈥� helped about 200 current undergraduates around the country polish nearly 900 essays for various scholarship applications. Their efforts helped secure nearly 40 scholarships for students who now attend 17 different colleges.

“Our organization was on a budget of $1,300 for the entire year and we generated $266,000 in scholarship money for students,” Coven said. “Our message at the pitch competition was that the results are there, we just need to scale it up.” He plans to use the money to set up regional chapters, offer more workshops and events and recruit more volunteers to help read student essays.

Coven enrolled at the UW in 2012 as a freshman in the Department of Mechanical Engineering. He had participated in the College of Engineering’s intensive the summer before his senior year of high school, which he says built the foundation for his later opportunities.

Mathematics Academy led to Coven’s selection for the in clean energy research,聽then the , where he worked in a mechanical engineering cellular biomechanics lab.

“David hits so many of the criteria that we wish for in our UW students, all in one dynamic, optimistic and truly amazing person,” said , engineering’s associate dean for diversity and access, who worked with Coven in Mathematics Academy.

Now, Coven is pursuing a mechanical engineering degree with a mathematics minor. He likes the flexibility the department offers and the range of topics he can learn.

In addition to his classes, Coven works in the lab of , an associate professor of materials science and engineering, creating materials for use in flexible solar cells to make them more lightweight and transportable, and to be potentially woven into fabric.

“David has a bubbly, outgoing personality and his enthusiasm is contagious,” Luscombe said.

Working in the lab alongside doctoral-level researchers is “intense,” Coven says with a smile. His experiments often turn out differently than expected, forcing him to start at square one again and again. But he says the experience is valuable.

“The thing I love about undergraduate research is you come in knowing nothing or very little and you learn a ton and get a lot of responsibility. You end up coming away day after day with Ph.D.-level analysis, techniques and understanding, no matter what year you are,” he said.

Coven’s company is , started last May with 11 of his friends and roommates. They focus on several different areas, including helping students find research and internship opportunities, teaching innovation through microlending, a home-sharing-like concept for storage, and even buying and selling specialized parts for longboards 鈥� a sport they are passionate about.

“The idea was to find something you can do and build with people you really care about and enjoy being around,” Coven said.

He grew up in Seattle’s Central District and went to Cleveland High School. Coven excelled in school despite a difficult childhood that included periods of homelessness. He finds exhilaration and escape in longboarding and still returns to the Interstate 90 pedestrian tunnel for a good ride with his best friend from childhood.

Coven said his close friends and a high school teacher were crucial to聽helping him succeed despite these difficulties.

“Being homeless was the hardest thing I’ve ever had to do in my life,” he said. “It taught me the true value of success should be measured by the happiness we find, and can cultivate in others, rather than material possessions.”

He’s applying to the program and hopes to go to graduate school when he finishes at the UW. But, depending on how his startup business takes off, he could pursue that.

For now, Coven appreciates being a student with a calendar full of opportunities.

“I always tell people, don’t be afraid to fail and understand failure is going to happen whenever you’re looking for something new,” he said. “If you never fail, you never understand and push the boundaries of who you are. This is the biggest lesson I’ve learned in my entire college career.”

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