The proposed photoluminescence calibration standard comprises a solid-state phosphor film, neutral density gel filter(s), and a 3D-printed optomechanical cartridge. The proposed standard demonstrated exceptional photostability; photoluminescence did not deviate from the baseline more than 1.27% under 5 minutes of continuous illumination. Remarkably, there was no measurable degradation over a 3-year study. Precise photoluminescence intensity modulation was accomplished with neutral density gel filters (R2 > 0.9982) and optical apertures (R2 > 0.9970). A model for photoluminescence intensity as a function of neutral-density filter and optical aperture parameters yielded a mean percentage error (MPE) of 2.79%, indicating high precision. Inter-sample variability was low, with a mean coefficient of variation (CV) of 1.32%. Mean CV across 24 channels decreased from 11.88% to 1.51% following multi-point calibration of multichannel point-of-care (POC) fluorometers. Cost analysis revealed a per-unit cost between $0.49 to $1.80. This work suggests that the proposed calibration standards provide a cost-effective, highly stable solution for reliable fluorometer calibration in low-resource settings.

Optogenetics presents an alternative method for interfacing with the nervous system over the gold-standard of electrical stimulation. While electrical stimulation requires electrodes to be surgically embedded in tissue for in vivo studies, optical stimulation offers a less-invasive approach that may yield more specific, localized stimulation. The advent of optogenetic laboratory animals-whose motor neurons can be activated when illuminated with blue light-enables research into refining optical stimulation of the mammalian nervous system where subsets of nerve fibers within a nerve may be stimulated without embedding any device directly into the nerve itself. However, optical stimulation has a major drawback in that light is readily scattered and absorbed in tissue thereby limiting the depth with which a single emission source can penetrate. We hypothesize that the use of multiple, focused light emissions deployed around the circumference of a nerve can overcome these light-scattering limitations. To understand the physical parameters necessary to produce pinpointed light stimulation within a single nerve, we employed a simplified Monte Carlo simulation to estimate the size of nerves where this technique may be successful, as well as the necessary optical lens design for emitters to be used during future in vivo studies. By modeling multiple focused beams, we find that only fascicles within a nerve diameter less than 1 mm are fully accessible to focused optical stimulation; a minimum of 4 light sources is required to generate a photon intensity at a point in a nerve over the initial contact along its surface. To elicit the same effect in larger nerves, focusing lenses would require a numerical aperture > 1. These simulations inform on the design of instrumentation capable of stimulating disparate motor neurons in mouse sciatic nerve to control hindlimb movement.

1. K.R. Anthony, P.V. Ridd, A.R. Orpin, P. Larcombe and J. Lough. “Temporal variation of light availability in coastal benthic habitats: Effects of clouds, turbidity, and tides,” Limnology and Oceanography, 49(6), pp.2201-2211. 2004. 2. J. Senko, "Sustaining Small-Scale Fisheries: Ecological, Social, and Policy Challenges and Solutions." Order No. 3738953, Arizona State University, Ann Arbor, 2015. 3. C. Kelley, A. Krolick, L. Brunner, A. Burklund, D. Kahn, W. Ball, and M. Weber-Shirk, “An Affordable Open-Source Turbidimeter,” Sensors, vol. 14, no. 4, pp. 7142–7155, Apr. 2014. Light-based bycatch reduction technology relies on light transmission through turbid marine environments. The causes of turbidity vary across marine environments, therefore, different wavelengths may be better suited for a given environment[1]. This study seeks to find the relationships between turbidity, wavelength and transmittance to inform effective bycatch reduction technology.

Fisheries bycatch is a cause of worldwide risk to marine biodiversity, which is largely detrimental to fisheries and marine environments. Marine megafauna such as sharks, sea turtles, and sea lions are susceptible to entanglement and possible death as incidental bycatch. Previous studies have shown that green lights on fishing gear effectively deter marine species and prevent entanglement in nets and longlines. Various light sources will be placed in turbid marine environments with their transmissivity recorded to find the most effective wavelength of light for a given marine environment.

Point-of-care (PoC) testing systems aim to bring affordable and convenient diagnostics to resource limited locations. In our previous work in detecting human papilloma virus (HPV) via lateral flow immunoassays and fluorescence detection, we determined that the performance of the assay depends on the temperature and humidity. Thus, we need to maintain a fixed environment for the assay to produce reliable results. Therefore, we define the need for a portable, climate-controlled chamber for field work in low resource settings. By combining low-cost electronics and household items, a simple feedback loop is designed to regulate the internal conditions of the testing environment. The ability of our chamber to maintain a desired climate will be tested for accuracy and stability to ensure that it is competent for in-field usage.

We present a novel 3D printed Microfluidic Actuation System for lateral flow assay in low resource settings. The system is used to deliver reagents for multi-step assays from blisters placed into cavities in the 3D printed assembly. The system is operated by manually depressing the blister housing and rotating to the next blister location. This is repeated for each step in the assay to enable a simple and repeatable method of delivering specified volumes to the assay at arbitrary time intervals as required by the assay. The blisters provide for robust storage while maintaining consistent aliquots for the assay. We characterize the percent of the total volume delivered to the lateral flow assay from the blisters including the volume dispensed at given time intervals.

Surface‐sensitive UV Raman spectroscopy is used to analyze the crystallinity of silicon films less than 20 nm thick directly on silicon wafers. The 325‐nm excitation has a Raman detection thickness of only 13 nm within the silicon film, thus eliminating signal from the substrate. We demonstrate measured crystallinities of microcrystalline silicon thin films that are consistent with the microstructure observed in transmission electron microscopy. Comparison is also made to ellipsometry, which is less able to accurately determine crystallinity than UV Raman spectroscopy. The UV Raman approach is particularly useful for layers grown on substrates of the same material but with different microstructure, and can be extended to non‐silicon materials.

We investigate the optimization of laser ablation with a femtosecond laser for direct and indirect removal of SiNx on alkaline textured c-Si. Our proposed resist-free indirect removal process uses an a-Si:H etch mask and is demonstrated to have a drastically improved surface quality of the laser processed areas when compared to our direct removal process. Scanning electron microscope images of ablated sites show the existence of substantial surface defects for the standard direct removal process, and the reduction of those defects with our proposed process. Opening of SiNx and SiOx passivating layers with laser ablation is a promising alternative to the standard screen print and fire process for making contact to Si solar cells. The potential for small contacts from laser openings of dielectrics coupled with the selective deposition of metal from light induced plating allows for high-aspect-ratio metal contacts for front grid metallization. The minimization of defects generated in this process would serve to enhance the performance of the device and provides the motivation for our work.

Copper-plated contacts for front side crystalline silicon solar cells are a topic of considerable interest, with many recent publications presenting a variety of successful methods and impressive cell results. Several of the more obvious challenges yet to be proven relate to the durability and reliability of plated contacts, especially the adhesion of plated metal to solar cells and the long-term stability of the metals that could potentially result in gradual power degradation. In this work, we have fabricated copper plated cells using several different front side patterning methods. For a resist-based process, we have optimized plated cell processing to achieve adhesion comparable to screenprinted silver paste contacts. For laser-based patterning methods, greater understanding of the metal-silicon interface and microstructure effecting adhesion is still needed.

The photovoltaics industry is expected to slowly transition from p-type mono-Si cells to n-type mono-Si over the next several years. Diffusion of boron into silicon to fabricate a p+ emitter can result in an efficiency-reducing boron rich layer (BRL) which can be removed reliably with an NF3 dry-etch process. The emitter should be passivated with a film that does not result in minority carriers being attracted to its surface. Boron was diffused from a-Si films deposited by PECVD on both sides of n-type Si substrates of 3.3 ohm-cm. The emitters were dry etched with nitrogen trifluoride (NF3). Best results for effective lifetime (198 μs) and emitter saturation current (31.6 fA/cm2) were realized on a sample etched to 89 Ω/□ from 71 Ω/□, then passivated with 10 nm of Al2O3 and 70 nm of SiNX and subsequently annealed in N2/H2 @ 450°C for 60 minutes.

Silicon (Si) heterojunction solar cells with efficiencies approaching 24.7% are poised to replace Si diffused junction solar cells. To further improve their efficiency, microcrystalline Si (μc-Si) could replace the amorphous Si (a-Si) emitter layer, thus improving the effective doping and increasing transparency. This improvement in efficiency would come at little additional cost and could be accomplished by altering the plasma-enhanced chemical vapor deposition (PECVD) conditions. A μc-Si film was deposited on glass, a-Si, c-Si, silicon dioxide, and sapphire. When integrated over the AM 1.5G spectrum, the a-Si:H film absorbs 3 mA/cm 2 the 50% crystalline μc-Si:H film absorbs 1.7 mA/cm 2 .