Arrhythmias kill 300,000 people annually and effective cardiac drugs are imperative in their management. However, heavy reliance on in vivo testing results in low throughput and ineffective preclinical prediction of human response. Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are a promising cell source for highly predictive, high-throughput in vitro testing. Unfortunately, culture conditions in current hPSC-CM assays leave hPSC-CM tissues immature, making them ineffective at modeling human myocardial drug responses. Tissue culture conditions that mimic the myocardial microenvironment promote the maturation of hPSC-CMs with higher efficiency than non-mimetic conditions. Taking advantage of this, our lab's NanoMEA system successfully melds biomimetically nanopatterned substrates with microelectrode arrays (MEAs) that perform high-throughput electrophysiological analyses of in vitro tissues. However, greater maturation efficiency is necessary to improve NanoMEA screening throughput. Electrically conductive environments promote hPSC-CM maturation, and numerous electrically conductive scaffolds exist. Yet, overlaying MEA electrodes with these substrates results in noisy signals that bar automatic processing. NanoMEA nanopatterns are made of Nafion, a nanoporous polymer that does not negatively impact the recordings from underlying MEAs. Since Nafion exhibits robust self-assembly with electrically conductive reduced Graphene-Oxide (rGO) molecules, we hypothesize that Nafion-reduced Graphene-Oxide (NrGO) nanopatterns will convey the benefits of conducting surfaces without impacting signal clarity. To investigate this, NrGO-nanopatterns are fabricated and characterized using Raman Spectroscopy, transmission electron microscopy, scanning electron microscopy, and conductive atomic force microscopy. Then, hPSC-CM monolayers are cultured on NrGO nanopatterns of varying rGO content and differences in morphological and transcriptional maturation markers are assessed. Promising NrGO nanopatterns are then integrated into a multiwell MEA platform to examine their effects on signal clarity and electrophysiological hPSC-CM maturation. If effective, we anticipate that this enhancement to the NanoMEA system will enable faster development of safer drugs, reducing animal model reliance, and improving the treatment of arrhythmias.

Ankle foot orthoses (AFOs) are commonly prescribed to improve gait in individuals with cerebral palsy to stabilize gait. AFOs have also shown additional benefits in reducing the metabolic cost of walking, preventing bone deformities, and providing support during gait. The advent of the affordable 3D-printer has provided a new tool in the manufacturing of AFOs which may be able to overcome many limitations of current production methods. The purpose of this study is to improve the manufacturability and functionality of AFOs by improving AFO design and manufacturing techniques. Validation testing through the use of material testing, and multiple subject gait experiments verified the study’s results. The subjects’ lower leg was scanned with a portable 3D scanner and using this scan the AFO was form fitted to the unique shape of the subject’s foot. Parametric and non-parametric computer aided design tools were used to design the AFOs. Using a fused deposition modeling 3D printer the AFOs were fabricated using polylactide (PLA) filament. In order to adjust the stiffness of the AFO, elastic polymer bands were fabricated with polyurethane. Since a single elastic polymer band only allows for one specific AFO stiffness, multiple of elastic polymer bands might be need to be used to control the wide range of AFO stiffness. To solve this issue, the AFO was designed to have a support structure that allows for the moment arm of the elastic polymer bands to be changed, thereby adjusting to a wide range of AFO stiffness with minimum number of elastic polymer bands. Designing an open-source, 3D-printed AFO that helps rehabilitate the user could allow for low-cost, easily accessible rehabilitation devices to be common place.

Organic photovoltaics (OPV) have emerged as a focus in photovoltaic research due to low-cost, simple, and high-throughput manufacturing capabilities. Still high vacuum deposited metals such as silver (Ag) are required for the top electrode of the cell, limiting size due to the high cost of silver, and throughput. This will significantly limit the performance of OPVs as larger sizes are necessary for many practical applications. My research addresses these important engineering issues by developing an alternative deposition method with less expensive materials. Therefore I plan to replace vacuum deposited Ag with electroplated copper (Cu). Recently it has been shown that high vacuum deposition can be replaced with low-cost metallization techniques such as electroplating. Electroplating is a well-established industrial process that is relatively low-cost, and simple, making it a suitable choice for rapid processing. While electroplating technology has been adopted for silicon-based photovoltaics, its advantages and implications have yet to be explored in OPVs. Cu is a significantly lower-cost material when compared to Ag with comparable conductivity characteristics as to not harm OPV performance. My method of investigation involves testing OPV performance once they are fabricated, then electroplate a thick Cu electrode on top of the Ag electrode, followed by once again testing OPV performance. My plan is to then characterize the effects of the electroplated Cu on the power conversion efficiency (PCE) or the ability to convert the sun’s energy into electrical energy of the OPV. Successfully replacing a sophisticated manufacturing process with simple methods, and cheap materials such as electroplated Cu, would create opportunities for further technology to be developed for OPV.

The performance of polymer solar cells (PSC) have been a popular study in its applications and fabrication processes in the field of solar energy. Although the power conversion efficiency (PCE) for this type of organic solar cell increased to about 6%, there is a need for the improvement in its device architecture. Creating solar cells involve a strategic fabrication process that consists of several layers that must be built in sequence. Each layer serves a crucial role. The primary role in the performance of its PCE is in optimizing the parameter of transport layers that facilitate charge carriers from the active layer. Fabricating solar cells start with a premade indium-tin oxide (ITO) coated electrode glass slide, followed by ZnO, an electron transport layer (ETL) created with specific measurements. The active layer, P3HT:PCBM is then created with appropriate concentration levels. MoO₃, a hole transport layer (HTL), is deposited on top of the active layer, at a different thicknesses. Lastly, Ag is deposited to serve as our second electrode. Completing the solar cell with the second electrode completes the circuit. Electron charge carriers transport through ZnO to ITO, while the hole charge carriers transport through MoO₃ to Ag. My research, therefore, aims to address what is the optimized thickness of the hole transport layer (HTL), MoO₃, in order to further improve the PCE. In focusing on MoO₃, results determined that as the layer thickness of MoO₃ is reduced, the PCE increases. In opposition, as the layer thickness of MoO₃ increases, the PCE decreases. By controlling the thickness of the hole transport layer, this allowed me to find an optimized thickness to produce high PCEs. This research opens new possibilities and opportunities for future processes when optimizing a particular layer.