Symposium SB03: Thin-Film Devices, Barriers and Their Reliability

Shantanu Nikam, the University of Akron and Duke University 

Anti-Adhesive Bioresorbable Elastomer Coating That Reduce Intraperitoneal Adhesions in Abdominal Repair Procedures 

Written by Richard Wu

Every year, thousands of patients who have abdominal surgeries suffer from intraperitoneal adhesions (IAs), which are bands of excess scar tissue that form between internal organs and the abdominal wall. IAs can mechanically constrict organs such as the intestines, leading to problems such as intestinal blockage, pain, inflammation, and infection. Patients suffering from IA complications often need further surgery and rehospitalization, resulting in further healthcare costs.

Shantanu Nikam, from the University of Akron and Duke University, is designing a solution to help reduce IAs in abdominal hernia repair surgeries. Hernia repair surgeries require implanting a mesh in the body to mechanically support damaged tissue during healing. However, these mesh implants can cause inflammation and scarring within the abdomen, which can lead to IA formation. Nikam’s research group has synthesized a new mesh implant that has a biodegradable coating made from a zwitterionic elastomer material. The coating is formulated to be resistant to IA formation and can withstand mechanical stresses from activities such as coughing, jumping, or stretching. As seen in experiments on rabbits, the coated mesh implants significantly reduced IA extent compared to standard uncoated mesh implants, suggesting that the new mesh implants have potential to reduce surgical complications.

Symposium EL13: Organic Materials and Devices for Neuronal/Neuromorphic Processing, Adaptive Sensing and Actuation

Molly Stevens, Imperial College London 

Designing Bioelectronic Materials for Regenerative Medicine 

Written by Richard Wu 

Polymer materials have many potential biomedical applications. The Stevens Group at Imperial College London, led by Molly Stevens, is developing bioelectronic polymer materials for regenerative medicine and therapeutic uses. Stevens reported methods to chemically modify the molecular structures of various polymers, which has allowed the research group to fine-tune the polymers’ material properties. These modified polymers can exhibit unusual behaviors, such as electrical conductivity, light sensitivity, and self-degradation in response to a stimulus.

Using these bioelectronic polymer materials, the researchers have been working to address a number of important medical challenges. Their work has led to the development of many innovative technologies, including electrically conductive heart patches that could one day help treat heart attack victims, light-responsive biosensors that are able to locate cancer cells, and microrobots that can selectively deliver drugs to cells in the body. Given the number of potential biomedical applications, it is exciting to see how these bioelectronic polymer materials can be used to improve human health and treat disease.

2023 MRS Spring Meeting & Exhibit: Science as Art Competition

Congratulations to our winners!

2023 MRS Spring Meeting & Exhibit - Graduate Student Awards

Congratulations to this year's students!

The MRS Graduate Student Awards are intended to honor and encourage graduate students whose academic achievements and current materials research display a high level of excellence and distinction. In addition to the MRS Graduate Student Gold and Silver Awards, the Arthur Nowick Graduate Student Award, which honors the late Dr. Arthur Nowick and his lifelong commitment to teaching and mentoring students in materials science, is presented to a GSA finalist who shows particular promise as a future teacher and mentor.

 

Symposium EL08: Nanogenerators and Piezotronics

Yuljae Cho, University of Michigan–Shanghai Jiao Tong University Joint Institute 

Hybrid Smart Fiber with Spontaneous Self-Charging for Wearable Electronic Applications 

Written by Richard Wu

Wearable electronics, which have become increasingly widespread in recent years, have many potential applications for biomedical devices. However, an important limitation of many wearable electronic devices is the need for an external energy supply, which may not always be available or practical in biomedical applications.

Yuljae Cho, from the University of Michigan–Shanghai Jiao Tong University Joint Institute, has been working to address this need by designing and experimenting on hybrid smart fiber materials which are capable of self-charging. When subjected to mechanical forces such as tugging or pulling, these smart fiber materials can convert the movement into electricity and power a small light. The smart fibers are also quite durable and can endure repeated mechanical stresses, such as from bending, knotting, and even washing.

While this work is still ongoing, the hybrid smart fibers have a lot of potential applications. Thanks to their self-charging properties and durability, these smart fibers may soon be powering the next generation of biomedical devices and other wearable electronics. 

Symposium SB01: Fundamentals and Applications of Engineered Living Materials

Written by Grace Hu

Jérémie Caprasse, University of Liège

Microfluidic Shape-Memory Microparticles for Embolization System

Microfluidic techniques are elevating our ability to produce uniform immersion droplets and multifunctional materials. Jérémie Caprasse from the University of Liège has been refining his microfluidic formulation of shape-memory microparticles to serve as an embolization system. Embolization is a voluntary, minimally invasive procedure that involves the selective occlusion of blood vessels to gain medical benefits, such as controlling abnormal bleeding, inhibiting blood supply to a tumor, and treating aneurysms. Caprasse looks at modifying the hard and soft segments of shape-memory polymers, which fix the permanent and temporary shape of the material respectively, in response to thermal stimuli.

Caprasse aims to optimize the process of forming well-defined, monodisperse microparticles composed of 4-arm poly (ε-caprolactone) stars crosslinked by coumarin. He then tested a few conditions on his microparticle formulations and found that increasing the emulsifier concentration and/or decreasing the polymer flow led to smaller microparticle sizes (overall range of 50–150 µm). By performing differential scanning calorimetry, he also showed that the 38% crystallinity imparts shape memory such that the elastic material recovers its initial shape within 30 seconds. Ultimately, having tunable control of microparticle synthesis with shape memory is a promising technique for embolization applications.

 

Ryan Trueman, University College London

3D Aligned Engineered Living Conductive Neural Tissue

Severed nerve injuries are a major challenge for patients today since a stable connection is needed to bridge the gap. The gold standard treatment is to perform a surgical autograft, where a patient’s own nerve tissue from another site of the body is extracted to fill the gap. However, the surgical method has shown side effects of nerve loss at the donor site and poor recovery satisfaction. As such, a speaker filling in for Ryan Trueman said the research group aims to explore how electrical stimulation (ES) can be leveraged to promote nerve regeneration.

To do so, the research team has designed a composite scaffold of polymerized polypyrrole nanoparticles and fibrillar collagen processed through a technique known as gel aspiration-ejection. This conductive scaffold then served as a carrier for therapeutic Schwann cells to help bridge primary rat neurons that were seeded in as well. They demonstrated how the cell-laden constructs were able to align the Schwann cells and help maintain cell viability, where electrical stimulation also did not incur additional cell death. In fact, electrically stimulating the Schwann cells in the scaffold resulted in increased neurite extension in the monolayer, which shows potential for ES as a promising therapy for nerve regeneration in the future.

 

Daniel Verrico, Case Western Reserve University

Cell Encapsulation and Functionality in Engineered Living Microfibers by Uniaxial Electrospinning

Like humans settled into their home, a cell flourishes best in the comfortable microenvironment that they grow in. But how can we replicate complex in vivo conditions through in vitro geometric lattices? PhD student Daniel Verrico from Case Western Reserve University, in collaboration with researchers in the Lawrence Livermore National Laboratory, tries to tackle this problem by fabricating a novel poly(ethylene glycol) (PEG) scaffold for single cell encapsulation and bioprocess intensification. Here, Verrico used a novel uniaxial electrospinning approach to generate PEG microfibers, which were then characterized and loaded with viable yeast cells to facilitate mass transfer and increase production capacity.

Diving into the results, Verrico first showed how varying the initial concentration of aqueous poly(ethylene glycol) diacrylate (PEGDA) from 5 wt% to 15 wt% led to pretty consistent fiber diameters (0.7–0.9 µm), but at a cost of higher embrittlement. Rehydrating the scaffold also induced a thicker web-like structure with agglomerated morphology. To strengthen the gel, Verrico created dual network fibers composed of 5 wt% acrylamide and 0.5 wt% N, N′-methylenebisacrylamide, which helped reduce brittle behavior and improve elasticity.

Going forward, Verrico hopes to perform in situ photopolymerization to cure the electrospun material and evaluate impacts on morphological outcome. Overall, designing biomaterials to promote yeast cell functionality can help produce valuable products such as biofuels and pharmaceuticals, offering a strong candidate for biocatalyst production.

Symposium SF03: Emerging Thermal Materials—From Nanoscale Heat Transport, Devices and Applications, to Theories

Yeongju Jung, Seoul National University

Bio-Inspired Artificial Butterfly Wing-Like Membrane

Written by Ekaterina Antimirova

Butterflies inhabiting warmer climates exhibit distinctive evolutionary adaptations in the form of ridges and porous microstructures on their wings, which enable display of vivid coloration while simultaneously effectively thermoregulating. In pursuit of understanding and augmenting these natural characteristics, PhD candidate Yeongju Jung has focused on the design of butterfly-wing-inspired thin films for addressing climate change and enhancing aerospace coatings.

He and his labmates have harnessed laser interference lithography to meticulously create microscale ridge structures that emit varying colors depending on the distance between the ridges. To achieve the thermoregulatory properties, the team utilized a straightforward solution-process fabrication method, resulting in randomly distributed pores within the material. This porous structure enhances cooling efficiency by reflecting light in the visible spectrum, while concurrently absorbing it in the infrared radiation region.

To validate both phenomena, the research group conducted rigorous experiments, particularly noting an average reduction in surface temperature of approximately 8°C during a full day outdoor test.

Symposium EL09: Layered (2D) Optoelectronic Materials and Devices

Written by Cullen Walsh

Joel Martis, Stanford University

Imaging the Electron Charge Density in Monolayer MoS₂ using 4D Scanning Transmission Electron Microscopy

Monolayer MoS₂ is a versatile platform for optoelectronics and catalysis, being used in transistors, photodetectors, and single-atom catalysts. To better understand these materials, Joel Martis from Stanford University wants to know, “can we directly image the electron charge density at the atomic scale?” Up to now, researchers have predicted charge densities in these materials using computational techniques, such as density functional theory (DFT). To experimentally image these charge densities, Martis is using a technique known as four-dimensional scanning transmission electron microscopy (4D STEM). This involves focusing an electron beam onto a sample and measuring the deflection of the electrons off the atoms via a pixelated detector. Using this technique, Martis can image the electric fields then convert those images into a net charge density map. Additionally, by using a technique called high angle annular dark field (HAADF), he can then separate out the nuclear and electron components. Martis compared the contributions from the core and valence electrons and found that the electron probe beam blurs out the contributions from the valence electrons. In the future, he wants to deconvolve the probe shape from his experiments to better understand the distribution of these valence electrons.   

 

David Xu, Northwestern University

Conversion of Classical Light Emission from a Nanoparticle-Strained WSe₂ Monolayer into Quantum Light Emission via Electron Beam Irradiation

Quantum information science solves many classically unsolvable problems. For instance, quantum communication can be used to prevent eavesdropping between conversations. One important structure for achieving these quantum technologies is a single photon emitter. An ideal material platform for these emitters is two-dimensional materials, such as monolayer transition metal dichalcogenides (TMDCs), due to their strong light-matter coupling and strain-dependent optoelectronic properties. However, the origin of single photon emitters in TMDCs is still poorly understood. To better understand these single photon emitters, David Xu from Northwestern University created strained monolayer TMDCs, since strain has been shown to help induce single photon emitters. He then irradiated these samples using an electron beam. What he found was that electron beam irradiation activated previously non-existent single photon emitters in the material. As a result, this methodology allowed him to convert classical emission channels in the materials into quantum emission channels. This could open new pathways for quantum information science using these materials.

Symposium SF03: Emerging Thermal Materials—From Nanoscale Heat Transport, Devices and Applications, to Theories

Rohith Mittapally, University of Michigan, Massachusetts Institute of Technology

Probing Performance Improvements in Thermophotovoltaic Energy Conversion at Nanoscale Gaps

Written by Kunwar Abhikeern

Thermophotovoltaic (TPV) systems are a type of technology that can generate electricity directly from heat. They work by using a hot emitter that faces a cold photovoltaic cell (PV). When radiation is emitted from the hot emitter and hits the PV cell, it generates electricity. However, the amount of electricity produced by TPV systems is limited when the gap between the emitter and the PV cell is too large.

Recent studies have suggested that if the gap between the emitter and the PV cell is reduced to very small distances, the power output of the TPV system can be increased beyond the previous limit. This is because the radiation emitted by the hot emitter can be more efficiently absorbed by the PV cell when they are very close together.

Rohith Mittapally, a postdoc at the University of Michigan and MIT, discussed his research team’s work on TPV systems. The researchers used experimental techniques to place a hot silicon emitter very close to an InGaAs-based PV cell. This resulted in a significant increase in power output, as the PV cell was able to more efficiently absorb the radiation from the emitter.

Mittapally’s team used a step-by-step approach to find the maximum power output values. They reduced the gap between the emitter and the PV cell to less than 500 nm and increased the temperature to achieve a record-high power density output of 0.5 Watts per square centimeter at an efficiency of 6.7 percent.

Their work is significant because it brings us closer to making more efficient TPV systems that can produce more electricity from heat. The team’s future goal is to achieve an efficiency of more than 30%, which would make TPV systems even more practical and useful.

Symposium EL18: Material, Device, and Fabrication Innovations for Flexible, Stretchable, and Printed Electronics

Hoayu Zhao, University of Southern Mississippi

Predictive Design of A Conjugated Polymer's Mechanical Property from its Dynamics

Written by Ekaterina Antimirova

Conjugated polymers (CPs) featuring a π-electron backbone have attracted interest in the field of biosensor research due to their significant potential for signal amplification in such devices. Nevertheless, understanding how their building blocks, backbone, and side chains influence mechanical properties remains an ongoing area of research, as described by Hoayu Zhao. The glass transition temperatures (Tgs) of CPs are directly related to their thermomechanical properties, so predicting these temperatures can serve as a valuable tool in the design and selection of these polymers.

The Gu research group at the University of Southern Mississippi has systematically varied both the building blocks within CPs and measured the resulting stiffness and viscoelastic properties. When the team performed backbone engineering, they observed that increased stiffness correlated with a higher Tg. Conversely, increasing the side chain length led to more flexible molecules, which resulted in a decrease in both Tg and stiffness.

Based on these initial experiments, the researchers developed machine learning predictive models for Tg and stiffness across various structures. Although the data demonstrated a good match, a more refined model can be achieved by incorporating additional literature and extensive data collection.