University of Michigan College of Engineering

In low- to middle-income countries (LMICs), fewer than half the people requiring rehabilitation for injuries receive the care that they need. In Ghana, for example, approximately 650,000 people live with wrist and hand injuries that are left untreated. One of the reasons for that is the high cost of assistive medical devices. The William Davidson Institute (WDI) at the University of Michigan is dedicated to developing creative ways of helping people in LMICs to thrive. One of its current projects is a 3D-printed hand-rehabilitation device that costs a fraction of conventional devices. The GripForté is a lightweight, 3D-printed hand rehabilitation device that costs only $14.77 to produce. It weighs 1.5 pounds and has a variable design to accommodate a range of exercises including grip, flexion, and pinching. The hope is that the 3D-printed device will allow individuals in Ghana and other LMICs to access the rehabilitative care they need. Students identify unmet need A student team at the University of Michigan initially identified the unmet need in Ghana, and a team of undergraduate mechanical engineering students then designed an initial prototype with input from a Ghanaian physical medicine and rehabilitation physician. The original design was made of wood and cost $1,477 to create in Ghana. Additional issues presented themselves: The device was too heavy and it used rubber bands to create resistance. Rubber bands are not readily available in Ghana. WDI routinely collaborates with local and national firms, University of Michigan students and faculty, and experts in a variety of fields. To address this particular issue, it enlisted the help of two aerospace engineers within the University of Michigan’s College of Engineering. That led to the development of a device using a 3D printer, solving the issues of cost and weight. It also included 3D-printed springs that could be swapped out to increase or decrease resistance. Positive patient and therapist feedback WDI has been working independently and with its partner in Ghana to solicit feedback on the device’s functionality — and the feedback has been highly positive thus far, both from patients and physical therapists. WDI continues to work to improve the device, with goals to reduce the cost to under $10 and the weight to under one pound. The organization also intends to 3D print the device’s bolts as well as springs with increased elasticity, plus add new, alternative panels with different exercises. Finally, it is exploring the idea of using recycled PET to print the device, reducing both cost and waste. Image courtesy of William Davidson Institute WDI President Paul Clyde (left) and University of Michigan Engineering graduate student David Sharp work on the GripForté device. “The ability to print equipment and components on demand using 3D printing is a huge benefit for the healthcare industry — especially in situations that call for high degrees of customization, which is the case with many medical applications,” said Claire Hogikyan, WDI vice president, administration, and project lead on the GripForté device. “From 3D-printed devices for surgical procedures to creating pop-up labs to print equipment, we see tremendous opportunity using 3D-printing technology.” Hogikyan points out that in LMICs, small things can easily disable medical equipment due to a lack of resources — an MRI machine may be out of commission for months waiting for a simple clip to be replaced. Injuries may also go untreated due to a lack of available splints. The healthcare practice group at WDI has made it its goal to identify new ways to improve both the quality of and access to healthcare in LMICs, and 3D printing is playing a large part in reaching that goal.

Rather than being solely detrimental, cracks in the positive electrode of lithium-ion batteries reduce battery charge time, research shows. This runs counter to the view of many electric vehicle manufacturers, who try to minimize cracking because it decreases battery longevity. Rather than being solely detrimental, cracks in the positive electrode of lithium-ion batteries reduce battery charge time, research done at the University of Michigan shows. This runs counter to the view of many electric vehicle manufacturers, who try to minimize cracking because it decreases battery longevity. "Many companies are interested in making 'million-mile' batteries using particles that do not crack. Unfortunately, if the cracks are removed, the battery particles won't be able to charge quickly without the extra surface area from those cracks," said Yiyang Li, assistant professor of materials science and engineering and corresponding author of the study published in Energy and Environmental Sciences. "On a road trip, we don't want to wait five hours for a car to charge. We want to charge within 15 or 30 minutes." The team believes the findings apply to more than half of all electric vehicle batteries, in which the positive electrode -- or cathode -- is composed of trillions of microscopic particles made of either lithium nickel manganese cobalt oxide or lithium nickel cobalt aluminum oxide. Theoretically, the speed at which the cathode charges comes down to the particles' surface-to-volume ratio. Smaller particles should charge faster than larger particles because they have a higher surface area relative to volume, so the lithium ions have shorter distances to diffuse through them. However, conventional methods couldn't directly measure the charging properties of individual cathode particles, only the average for all the particles that make up the battery's cathode. That limitation means the widely accepted relationship between charging speed and cathode particle size was merely an assumption. "We find that the cathode particles are cracked and have more active surfaces to take in lithium ions -- not just on their outer surface, but inside the particle cracks," said Jinhong Min, a doctoral student in materials science and engineering working in Li's lab. "Battery scientists know that the cracking occurs but have not measured how such cracking affects the charging speed." Measuring the charging speed of individual cathode particles was key to discovering the upside to cracking cathodes, which Li and Min accomplished by inserting the particles into a device that is typically used by neuroscientists to study how individual brain cells transmit electrical signals. "Back when I was in graduate school, a colleague studying neuroscience showed me these arrays that they used to study individual neurons. I wondered if we can also use them to study battery particles, which are similar in size to neurons," Li said. Each array is a custom-designed, 2-by-2 centimeter chip with up to 100 microelectrodes. After scattering some cathode particles in the center of the chip, Min moved single particles onto their own electrodes on the array using a needle around 70 times thinner than a human hair. Once the particles were in place, Min could simultaneously charge and discharge up to four individual particles at a time on the array and measured 21 particles in this particular study. The experiment revealed that the cathode particles' charging speeds did not depend on their size. Li and Min think that the most likely explanation for this unexpected behavior is that larger particles actually behave like a collection of smaller particles when they crack. Another possibility is that the lithium ions move very quickly in the grain boundaries -- the tiny spaces between the nanoscale crystals comprising the cathode particle. Li thinks this is unlikely unless the battery's electrolyte -- the liquid medium in which the lithium ions move -- penetrates these boundaries, forming cracks. The benefits of cracked materials are important to consider when designing long-lived batteries with single-crystal particles that don't crack. To charge quickly, these particles may need to be smaller than today's cracking cathode particles. The alternative is to make single-crystal cathodes with different materials that can move lithium faster, but those materials could be limited by the supply of necessary metals or have lower energy densities, Li said. The device was built in the Lurie Nanofabrication Facility and studied at the Michigan Center for Materials Characterization. The research was funded by LG Energy Solution, Battery Innovation Contest and the University of Michigan College of Engineering.

The researchers looked closer into the possibility of reprograming inner ear cells to repair long-term hearing loss. About 430 million people around the world experience disabling hearing loss. In the United States, approximately 37.5 million adults report some trouble hearing. Hearing loss can happen when any part of the ear or the nerves that carry information on sounds to the brain do not work in the usual way. For instance, damaged hair cells in the inner ear can lead to hearing loss. "These cells allow the brain to detect sounds," said Dr. Amrita Iyer, first author of a new paper published in eLife. Iyer was a graduate student in the lab of Dr. Andrew Groves, professor and Vivian L. Smith Endowed Chair in Neuroscience and of molecular and human genetics at Baylor College of Medicine, while she was working on this project. Hair cells are generated during normal development but this ability is progressively lost after birth as mammals mature. "When hair cells are lost in mature animals, the cells cannot be naturally regenerated, which can lead to permanent hearing loss," Iyer explained. "In the current study, we looked closer into the possibility of promoting hair cell regeneration in mature animals using cell reprograming. Our approach involved the overexpression of various transcription factor combinations." Transcription factors promote the expression of certain genes and prevent the expression of others. By changing the pattern of gene expression, the researchers hoped to lead cells to a state in which they would regenerate hair cells in mature animals similarly to what happens during development. "We compared the reprogramming efficiency of the hair cell transcription factor ATOH1 alone or in combination with two other hair cell transcription factors, GFI1 and POU4F3, in mouse non-sensory cells in the cochlea, the part of the inner ear that supports hearing," Iyer said. "We did this at two timepoints -- eight days after birth and 15 days after birth, assessing the extent of hair cell regeneration in mice." To study the structure of the hair cell bundles generated by reprogramming, Iyer collaborated with Dr. Yeohash Raphael's lab at the University of Michigan to perform scanning electron microscopy imaging on the cochleae of mice conditionally overexpressing these transcription factors. The images clearly showed that the hair cell bundles were in accordance to what is observed on inner hair cells during development. Further studies showed that these cells also had some characteristics that suggested that they were capable of sensing sound. "We found that although expressing ATOH1 with hair cell transcription factors GFI1 and POU4F3 can increase the efficiency of hair cell reprogramming in older animals compared to ATOH1 alone or GFI1 plus ATOH1, the hair cells generated by reprogramming at eight days of age -- even with three hair cell transcription factors -- are significantly less mature than those generated by reprogramming at postnatal day one," Iyer said. "We suggest that reprogramming with multiple transcription factors is better able to access the hair cell differentiation gene regulatory network, but that additional interventions may be necessary to produce mature and fully functional hair cells." These findings are key to advancing the existing understanding of the mammalian inner ear hair cell regeneration process. From a therapeutic standpoint, transcription factor-mediated reprogramming and the underlying biology associated with its function may enable fine-tuning of current gene therapy approaches for long-term hearing loss treatment. Other contributors to this work include Ishwar Hosamani, John D. Nguyen, Tiantian Cai, Sunita Singh, Melissa M. McGovern, Lisa Beyer, Hongyuan Zhang, Hsin-I Jen, Rizwan Yousaf, Onur Birol, Jenny J. Sun, Russell S. Ray, Yehoash Raphael and Neil Segil. The authors are affiliated with one or more of the following institutions: Baylor College of Medicine, the University of Southern California and the University of Michigan. The project was supported by the following grants: RO1 DC014832, R21 OD025327, DC015829 and a Hearing Restoration Project Consortium award from the Hearing Health Foundation. The project was also supported by funding from a CPRIT Core Facility Support Award (CPRIT-RP180672), NIH grants (P30 CA125123, S10 RR024574, S10OD018033, S10OD023469, S10OD025240 and P30EY002520), the R. Jamison and Betty Williams Professorship, the University of Michigan College of Engineering and NSF grant #DMR-1625671.