In the midst of the pandemic, our team prototyped a volatile organic compound (VOC) sensor that seeks to detect COVID-19 using mechanisms from our noses: olfactory proteins. In taking the concept from design to testing, a massive amount of data was compiled and produced. Protein sequences were gathered from hundreds of publications on odorant binding proteins (OBPs) and cross-referenced against protein structures in the Protein Data Bank (PDB), sensor molecules were simulated in molecular dynamics, and candidates were screened using multiple experiment methods. I built and deployed the database that tied together signature disease VOCs, protein binding affinities, and protein and peptide sequences, along with molecular dynamics experimental results. In addtion, I had also pulled seqeunces from PDB and had contributed to the literature search. We demonstrate how intelligent data management enabled and accelerated a project to tackle rapid detection of COVID-19.

Laser-induced graphene’s (LIG) simple and rapid fabrication has led to the development of flexible sensors with various applications in wearable electronics. LIG is produced in ambient air through CO₂ laser scribing on a polyimide film. Although LIG has been incorporated into flexible chemical and strain sensors, its sensitivity to resistance changes under deformation and instability prevents it from being fully utilized as a flexible conductor. This work presents a versatile technique to increase the electrical conductivity of LIG and enhance its structural stability so that it can be used as flexible conductors in printed electronics. This is achieved by the deposition and activation of functionalized liquid metal (LM) nanoparticles on LIG traces. To overcome the repulsion of LM on LIG’s surface, the CO₂ laser’s settings are adjusted to create LIG traces with a superhydrophilic inside and superhydrophobic border. Additionally, the adhesion between the LIG and LM was improved through surface functionalization of the liquid metal droplets. Our results show the resistance of LM-LIG traces to be 3 orders of magnitude smaller than that of LIG traces. Electromechanical characterization of the LM-LIG traces demonstrate low resistance changes under large bending deformations. The combination of the liquid-phase conductor and 3D structure of graphene enables the fabrication of customizable, solder-free, flexible circuits with high mechanical stability. We demonstrate this technique with the fabrication of flexible light-dependent resistor circuits that serve as a basis for further flexible sensor and biosensor exploration.

In this project, we measure electron flow in graphene, a 2-D lattice of carbon atoms, and compare the results to simulations. As current is passed through typical electrical devices, the electron’s diffusion is dominated by collisions with impurities in the atomic lattice, giving rise to the material's resistance, the opposition to flow. This is called ohmic conduction. However, clean graphene permits a more dynamic and exciting type of conduction-- the hydrodynamic regime. Here, electrons’ collisions with each other are significant, and their collective behavior becomes water-like. When measured over a range of temperatures, we find dips in the resistance, resulting from these hydrodynamic electrons’ tendency to “pull” one another along with the bulk. Like honey, these electrons have viscosity, which unlike resistance, is a property of the fluid. This research will further elucidate properties of the electron fluid. To complete this project, we fabricate graphene devices and study them in a table-top cryostat, measuring the current profile from 4K to room temperature. We are particularly interested in how this viscous fluid behaves as it encounters a boundary within the device, an open question in the field. Using a unique homebuilt experimental instrument, called the feedback-lockin amplifier, we visualize the flow of electrons around a small scan probe tip. Comparison with python simulations helps us elucidate the fluid's boundary conditions. This research will directly benefit the electronics industry. The next generation of computer chips will utilize 2-D materials such as graphene, potentially enabling the useful properties of hydrodynamic flow to be harnessed. For example, the reduced resistance inherent to hydrodynamic conduction may increase the power efficiency of transistors.

Creating novel anti-cancer drugs aimed at targeted glioblastoma multiform (GBM), a type of brain cancer, is slow, extremely expensive, and remains a persistent challenge within the medical field. To address this challenge, our team’s research project is aimed at creating scaffolds from chitosan-hyaluronic acid (CHA) to mimic the brain microenvironment and serve as a platform for high throughput screening (HTS) of cancer drugs. 3D culture systems can promote more cell-cell and cell-matrix interactions, which can closely mimic the in vivo extracellular matrix environment. Studies have shown that the drug resistance of 3D-cultured cancer cells can better reflect the in vivo situation, and thus can potentially improve the success rate in drug screening processes. CHA scaffolds are especially beneficial for culturing GBM cells, as hyaluronic acid (HA) is a major component in brain tissues. To generate the scaffolds, we used different freezing rates and temperatures to create freeze-dried 8 wt% CHA scaffolds with pore sizes of 60, 120 and 180 μm. We characterized the compressive modulus of the scaffolds using the Instron test machine, and the porosity using liquid replacement methods. Cell studies with 3 different cell lines are currently being conducted on these scaffolds, after which an AlamarBlue assay will be used to determine the optimal pore size for each cell line in terms of their growth and drug resistance. The results of this can prove that our CHA scaffolds have good flexibility in response to different cancer cell line 3D cultures and have good potential to be an HTS platform.

Cement is a large contributor to carbon dioxide (CO₂) emissions, and there is ongoing research to reduce this impact. The negative impact of carbon dioxide emissions on our atmosphere is a growing concern, so finding avenues to reduce such pollution is constantly sought after. Namely, studies have been conducted to explore the inclusion of natural fibers into the cement matrix, both cellulose-based and pure cellulose. For this reason, sustainable cement composites with mechanical performance comparable to ordinary cement are of interest. Cellulose has been proven to enhance mechanical compressive properties under certain processing conditions. Additionally, concrete is limited in applications due to its inherently weak tensile/flexural properties; to combat this, fiber reinforcements (often steel) are incorporated. Here, we compare the effects of different types of cellulose fibers as fillers in cement, specifically the effects in density, viscosity, and compressive strength. We used cellulose microfibers as well as nanofibers, with substantially different degrees of crystallinity and aspect ratios. Overall, the mechanical performance of mixtures produced with varying amounts of cellulose micro- and nan-fibers as well as varying water content were studied. We correlated the changes in viscosity, micromorphology, and compressive strength to rationalize the effects. Utilizing readily available natural fibers in the cement matrix will enhance the tensile properties of concrete structures while also reducing the harmful carbon dioxide emissions due to cement production.