From Unexpected Opportunity to Game-changing Discovery

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Category: Department News

Published: Tuesday, September 06 2022 00:01

In the world of startups, opportunity can come knocking in strange ways. Six years ago, Didier Depireux (Ph.D. ’91, physics) was doing research at the University of Maryland when he was approached by Sam Owen, a young scientist who said he’d developed a device to treat motion sickness. Depireux was skeptical but decided to check it out. 

“Since I get very severe motion sickness, I made a deal with him,” Depireux recalled. “I said, ‘I’ll come over with my car and you can drive me around while I use the device. If I haven’t thrown up after 20 minutes while I’m in the back of the car reading, I’ll join the effort.’”

The two made plans to meet in Washington, D.C., on a muggy July afternoon.  Didier Depireux

“So, I go to Georgetown. The windows are down, it’s hot, it’s humid and I’m thinking I will not make it past the first turn,” Depireux explained. “Owen is driving and I’m in the back seat using his device and reading my cellphone. And for the first time in my life—and I’m over 50 years old—I was able to read in the back of a car and not get sick. I thought, ‘I need to join this, this is amazing.’”

Thanks to that strange summer ride-along, Depireux joined Owen in launching a startup called Otolith Labs to address inner ear-related conditions and their often debilitating symptoms. Otolith’s noninvasive vestibular system masking technology—designed for acute treatment of vestibular vertigo—received the FDA’s Breakthrough Device designation and clinical trials are ongoing, with support from investors including AOL founder Jack Davies and billionaire entrepreneur Mark Cuban.

All of this sets the stage for a major test that could lead to the startup’s ultimate goal—FDA approval as early as next year.

“In July we told the FDA we want to do a large-scale pivotal trial with hundreds of participants,” Depireux explained. “If all goes well, we’ll have a meeting next summer where the FDA will approve us and then the device will become available.”

For Depireux, it’s the latest step on a bigger mission that has guided his career.

Didier Depireux“It’s mostly relevance,” he explained. “I would like my life to make a difference, that’s the one thing that keeps me going.”

From philosophy to physics

Depireux was raised in Belgium. A bright, thoughtful boy, he grew up with a strong interest in science and theory, thanks to his father, a physics professor, and his mother, a chemistry teacher.

“I was always very science-y,” Depireux recalled. “Initially, I wanted to become a philosopher and I read this 800-page book—I think it was Kant—and at the end of it I was like, ‘I still don’t know the answer, and I’m not even sure I understand the question anymore.’ That’s when I thought that’s not a good fit for me.”  

Depireux eventually gravitated toward physics. After receiving his B.S. in physics from the University of Liège in Belgium in 1986, he began his graduate work in physics at the University of Maryland, where he focused on string theory and met Distinguished University Professor of Physics Sylvester James Gates Jr., who quickly became a mentor and friend.

“Jim had a huge impact on me. He was a fantastic person to work with and he had so much positive energy,” Depireux said. “I still remember late one night I was working on something, and I was stuck and I wrote to him, and he said, ‘I’ll come over, let’s work this out.’ So we had office hours at 10:30 p.m. just because I couldn’t solve a problem.”

Depireux earned his Ph.D. in 1991 and went on to do postdoctoral work in Quebec, Canada, before returning to College Park in 1994. Inspired by his wife Pamela, who was getting her Ph.D. in neuropharmacology, Depireux took on the challenge of modeling the brain and studying how it processes sound. By 2001, he was also teaching a gross anatomy class at the University of Maryland School of Medicine.

“I think, to this day, I am the only string theorist who has taught gross anatomy,” he reflected.

From his research on the brain and hearing, Depireux shifted his focus to tinnitus—disruptive ringing in the ears. He explored possible treatments and eventually teamed up with former UMD Bioengineering Professor Benjamin Shapiro who was already working on the drug delivery challenges Depireux was trying to solve.

“I wanted to get drug delivery to the ear but I didn’t know how to do it,” Depireux said. “He had this method with nanoparticles to deliver drugs and I had the target so we started working together.”

In 2013, the two launched Otomagnetics, a startup that has made major strides in developing noninvasive methods to treat inner ear diseases and more.

“We’ve gotten very nice results as far as drug delivery goes and Otomagnetics is still an ongoing concern,” Depireux explained, “But raising money for drug delivery is the real challenge, because to get drug delivery to the ear is going to take hundreds of millions of dollars, and that hasn’t happened yet.”

Going all-in on Otolith

Depireux balanced his time between Otomagnetics, his UMD research and teaching at the School of Medicine until 2016, when he experienced Owen’s experimental motion sickness device for the first time. Depireux saw so much potential with the device that he went all-in on Otolith. 

“You have to have pretty strong resilience to join a startup—I went for a year and a half without a salary or anything,” Depireux explained. “It’s not like we didn’t have money, we just needed all of the money to develop the device, get the patents in, all of the things we had to do.”

Though Otolith started with a motion sickness device, its co-founders hoped to make an even bigger impact by developing a device for vertigo, debilitating dizziness often caused by problems in the inner ear.

And they had a plan.

“For tinnitus or ringing in the ears, some patients get relief from a noise masker—they can still perceive their tinnitus, but the noise masker allows them to ignore the tinnitus,” Depireux explained. “So Sam, my cofounder said, ‘Why don’t we come up with a noise masker for the vestibular system?’”

That’s exactly what they did. Their novel device, worn like a headband, treats vertigo by applying localized mechanical stimulation to the vestibular system through calibrated vibrations. 

Depireux says he never would have made it this far without physics.

“My physics training really helped me,” he explained. “In physics, you have this huge problem and you have to break it down. If it’s intractable, you make it tractable, break it into small, simple things we can understand and then we can solve it.”

Promising results and personal stories

Clinical trials of Otolith’s investigational headband have yielded promising results. In the first of a series of ongoing clinical studies, 87.5% of the 40 participants reported a reduction in their vertigo within five minutes of turning on the device. But for Depireux, it’s the personal stories that are most rewarding.

“Somehow my phone number was listed as an emergency contact on clinicaltrials.gov, which I thought would be for emergencies only,” he said. “I’d have patients calling me in tears, telling me, ‘When my grandkids visit, I can finally bend down and pick them up, and it used to be that just bending down would send me into such vertigo that I would have to go to bed for days.’ Or ‘For the first time in years, I’ve been able to walk around the block.’ That’s what really motivates me.”

It's been Depireux’s goal all along—doing relevant research that changes people’s lives.

“We cannot help 100% of vertigo patients, no device does that,” he reflected. “But if we can help even half of those patients, that’s really my hope.”

Looking back on a career path that’s been anything but predictable, Depireux appreciates every challenge and setback that got him to where he is today.

“Something can feel like a failure when things go wrong, but then later you realize you really learned something from it,” he reflected. “I’m so grateful I was given the opportunity to come to the U.S. and study physics and do research in College Park, do this random walk in my career and finally end up doing something that I feel has given me great meaning in my life.”

Written by Leslie Miller

Faculty, Staff, Student and Alumni Awards & Notes

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Category: Department News

Published: Friday, September 02 2022 00:01

We proudly recognize members of our community who recently garnered major honors, began new positions and more.

Women in Physics Group Changes its Name to Physicists of Underrepresented Genders

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Category: Department News

Published: Friday, September 02 2022 00:01

Women in Physics (WiP) has officially been renamed Physicists of Underrepresented Genders (PUGs) at the University of Maryland.

According to UMDPUGs (Physicists of Underrepresented Genders) physics graduate student Ina Flood, the group’s new president, the change reflects the organization’s ongoing commitment to fostering a supportive and encouraging community for all.

“Changing our name was a group decision initiated under Mika Chmielewski, our previous president,” Flood said. “The rationale behind this decision was to make it obvious that we’re committed to supporting people who might feel like they are underrepresented in the physics community. The name change is to help people feel that they’re included and welcome from the get-go.”

For more than a decade, WiP has provided physics undergraduate and graduate students with resources such as a mentoring program and networking opportunities. In addition to professional development events led by physics faculty members and professionals, the club also offered social programming like group study sessions, where members mingled and made new friends.

PUGs plans to continue the group’s ongoing programs and opportunities while taking a more proactive approach to supporting all members of the physics community. 

“As a university club, we’re already open to all people and sincerely welcome anyone who is interested in physics,” said incoming physics graduate student Kate Sturge (B.S. ’22, physics; B.S. ’22, astronomy), who was an active undergraduate member of WiP and is currently the PUGs webmaster and social media manager. “But this name change is our way of making ourselves more deliberate and explicit in supporting everyone in physics.”

Physics Chair Steve Rolston echoes the sentiment: "We value the contributions of everyone who shares our love of physics. We appreciate PUGs’ efforts to make that crystal clear."

Flood, Sturge and other PUGs members plan to do more to coordinate with other LGBTQ+ student organizations on campus. Flood said she hopes increased communication and collaboration will also help PUGs connect mentors with mentees and share more institutional knowledge about STEM and physics. The group also plans to develop more opportunities for safe in-person gatherings, including “study hours,” during which physics students gather to discuss and do homework together.

“Our biggest goal after our name change is to expand our accessibility and availability to members who may need guidance or community support during the school year,” Flood said. “It’s really important to our organization that we get people together, facilitate meaningful conversations and celebrate our shared identity as physicists.”

Compact Electron Accelerator Reaches New Speeds with Nothing But Light

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Category: Research News

Published: Friday, September 02 2022 00:01

Scientists harnessing precise control of ultrafast lasers have accelerated electrons over a 20-centimeter stretch to speeds usually reserved for particle accelerators the size of 10 football fields.

A team at the University of Maryland (UMD) headed by Professor of Physics and Electrical and Computer Engineering Howard Milchberg, in collaboration with the team of Jorge J. Rocca at Colorado State University (CSU), achieved this feat using two laser pulses sent through a jet of hydrogen gas. The first pulse tore apart the hydrogen, punching a hole through it and creating a channel of plasma. That channel guided a second, higher power pulse that scooped up electrons out of the plasma and dragged them along in its wake, accelerating them to nearly the speed of light in the process. With this technique, the team accelerated electrons to almost 40% of the energy achieved at massive facilities like the kilometer-long Linac Coherent Light Source (LCLS), the accelerator at SLAC National Accelerator Laboratory. The paper was published in the journal Physical Review X on September 16, 2022

“This is the first multi-GeV electron accelerator powered entirely by lasers,” says Milchberg, who is also affiliated with the Institute of Research Electronics and Applied Physics at UMD. “And with lasers becoming cheaper and more efficient, we expect that our technique will become the way to go for researchers in this field.”  An image from a simulation in which a laser pulse (red) drives a plasma wave, accelerating electrons in its wake. The bright yellow spot is the area with the highest concentration of electrons. In an experiment, scientists used this technique to accelerate electrons to nearly the speed of light over a span of just 20 centimeters. (Credit Bo Miao/IREAP)

Motivating the new work are accelerators like LCLS, a kilometer-long runway that accelerates electrons to 13.6 billion electron volts (GeV)—the energy of an electron that’s moving at 99.99999993% the speed of light. LCLS’s predecessor is behind three Nobel-prize-winning discoveries about fundamental particles. Now, a third of the original accelerator has been converted to the LCLS, using its super-fast electrons to generate the most powerful X-ray laser beams in the world. Scientists use these X-rays to peer inside atoms and molecules in action, creating videos of chemical reactions. These videos are vital tools for drug discovery, optimized energy storage, innovation in electronics, and much more.  

Accelerating electrons to energies of tens of GeV is no easy feat. SLAC’s linear accelerator gives electrons the push they need using powerful electric fields propagating in a very long series of segmented metal tubes. If the electric fields were any more powerful, they would set off a lightning storm inside the tubes and seriously damage them. Being unable to push electrons harder, researchers have opted to simply push them for longer, providing more runway for the particles to accelerate. Hence the kilometer-long slice across northern California. To bring this technology to a more manageable scale, the UMD and CSU teams worked to boost electrons to nearly the speed of light using—fittingly enough—light itself.

“The goal ultimately is to shrink GeV-scale electron accelerators to a modest size room,” says Jaron Shrock, a graduate student in physics at UMD and co-first author on the work. “You’re taking kilometer-scale devices, and you have another factor of 1000 stronger accelerating field. So, you’re taking kilometer-scale to meter scale, that’s the goal of this technology.”

Creating those stronger accelerating fields in a lab employs a process called laser wakefield acceleration, in which a pulse of tightly focused and intense laser light is sent through a plasma, creating a disturbance and pulling electrons along in its wake. 

“You can imagine the laser pulse like a boat,” says Bo Miao, a postdoctoral fellow in physics at the University of Maryland and co-first author on the work. “As the laser pulse travels in the plasma, because it is so intense, it pushes the electrons out of its path, like water pushed aside by the prow of a boat. Those electrons loop around the boat and gather right behind it, traveling in the pulse’s wake.”

Laser wakefield acceleration was first proposed in 1979 and demonstrated in 1995. But the distance over which it could accelerate electrons remained stubbornly limited to a couple of centimeters. What enabled the UMD and CSU team to leverage wakefield acceleration more effectively than ever before was a technique the UMD team pioneered to tame the high-energy beam and keep it from spreading its energy too thin. Their technique punches a hole through the plasma, creating a waveguide that keeps the beam’s energy focused.

“A waveguide allows a pulse to propagate over a much longer distance,” Shrock explains. “We need to use plasma because these pulses are so high energy, they're so bright, they would destroy a traditional fiber optic cable. Plasma cannot be destroyed because in some sense it already is.”

Their technique creates something akin to fiber optic cables—the things that carry fiber optic internet service and other telecommunications signals—out of thin air. Or, more precisely, out of carefully sculpted jets of hydrogen gas.

A conventional fiber optic waveguide consists of two components: a central “core” guiding the light, and a surrounding “cladding” preventing the light from leaking out. To make their plasma waveguide, the team uses an additional laser beam and a jet of hydrogen gas. As this additional “guiding” laser travels through the jet, it rips the electrons off the hydrogen atoms and creates a channel of plasma. The plasma is hot and quickly starts expanding, creating a lower density plasma “core” and a higher density gas on its fringe, like a cylindrical shell. Then, the main laser beam (the one that will gather electrons in its wake) is sent through this channel. The very front edge of this pulse turns the higher density shell to plasma as well, creating the “cladding.” 

“It's kind of like the very first pulse clears an area out,” says Shrock, “and then the high-intensity pulse comes down like a train with somebody standing at the front throwing down the tracks as it's going.” 

Using UMD’s optically generated plasma waveguide technique, combined with the CSU team’s high-powered laser and expertise, the researchers were able to accelerate some of their electrons to a staggering 5 GeV. This is still a factor of 3 less than SLAC’s massive accelerator, and not quite the maximum achieved with laser wakefield acceleration (that honor belongs to a team at Lawrence Berkeley National Labs). However, the laser energy used per GeV of acceleration in the new work is a record, and the team says their technique is more versatile: It can potentially produce electron bursts thousands of times per second (as opposed to roughly once per second), making it a promising technique for many applications, from high energy physics to the generation of X-rays that can take videos of molecules and atoms in action like at LCLS. Now that the team has demonstrated the success of the method, they plan to refine the setup to improve performance and increase the acceleration to higher energies.

“Right now, the electrons are generated along the full length of the waveguide, 20 centimeters long, which makes their energy distribution less than ideal,” says Miao. “We can improve the design so that we can control where they are precisely injected, and then we can better control the quality of the accelerated electron beam.”

While the dream of LCLS on a tabletop is not a reality quite yet, the authors say this work shows a path forward. “There’s a lot of engineering and science to be done between now and then,” Shrock says. “Traditional accelerators produce highly repeatable beams with all the electrons having similar energies and traveling in the same direction. We are still learning how to improve these beam attributes in multi-GeV laser wakefield accelerators. It’s also likely that to achieve energies on the scale of tens of GeV, we will need to stage multiple wakefield accelerators, passing the accelerated electrons from one stage to the next while preserving the beam quality. So there’s a long way between now and having an LCLS type facility relying on laser wakefield acceleration.” 

This work was supported by the U.S. Department of Energy (DE-SC0015516, LaserNetUS DE-SC0019076/FWP#SCW1668, and DE-SC0011375), and the National Science Foundation (PHY1619582 and PHY2010511).

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Story by Dina Genkina

In addition to Milchberg, Rocca, Shrock and Miao, authors on the paper included Linus Feder, formerly a graduate student in physics at UMD and now a postdoctoral researcher at the University of Oxford, Reed Hollinger, John Morrison, Huanyu Song, and  Shoujun Wang, all research scientists at CSU, Ryan Netbailo, a graduate student in electrical and computer engineering at CSU, and Alexander Picksley, formerly a graduate student in physics at the University of Oxford and now a postdoctoral researcher at Lawrence Berkeley National Lab.