AVS 72 Session UN-ThP: Undergraduate Poster Session

Gallium oxide (Ga₂O₃) is a polymorphic semiconductor material whose β phase demonstrates potential for applications in power electronics due to high Johnson and Baliga figures of merit. When compared to other materials commonly used in piezoelectric MEMS, metastable ε-Ga₂O₃ demonstrates a promising electromechanical coupling coefficient (k²) — highlighted in Table 1. Despite this, ε-Ga₂O₃ remains less studied than β-Ga₂O₃, which has been grown using melt, MOCVD, and PVD techniques.

This study presents initial results of the effects of different RF sputtering and annealing conditions on the crystal characteristics of thin-film Ga₂O₃ on <111> silicon substrates towards the goal of determining ideal temperature, gas type and flow ratio, and RF power values contributing to ε-phase stabilization. The study follows the process shown in Fig. 1.

Films were sputtered from a Ga₂O₃ target in 32 sccm of Ar at 3 mTorr with 50W RF power for 2 hours (Fig. 2) and subsequently annealed in an air-ambient tube furnace at 500 to 900°C in 100°C steps for 30 minutes at temperature. These temperatures were chosen based on literature showing the transition of ε- to β-Ga₂O₃ around 800°C. Samples were characterized before and after annealing with spectroscopic ellipsometry shown in Fig. 3 and XRR shown in Fig. 4.

Ellipsometry results indicate a slight decrease in film thickness at sub-600°C anneals with rapid expansion at higher temperatures (Fig. 3); XRR fringe spacing (Fig. 4), in contrast, indicates thickness expansion across all anneal temperatures, while critical angle right shift indicates densification and increasing slope indicates increasing roughness. This is supported by AFM (Fig. 5), which demonstrates a change in surface roughness from 66.59pm RMS (unannealed) to 1.858nm RMS (900°C) while also revealing the polycrystalline nature of the annealed films. XRD measurement did not yield clean spectra, likely due to the disoriented polycrystalline nature of the films.

Following literature on successful deposition of ε-Ga₂O₃, future work will explore deposition at elevated temperatures, while also varying O₂/Ar gas mixture, substrate bias, and deposition rate to enhance ε-phase stability and crystallinity.

This research seeks to understand how the hardness of poly (methyl methacrylate) (PMMA), a thermoplastic polymer, can be altered when it is infiltrated with an inorganic via vapor phase infiltration (VPI). In VPI, the polymer sorbs inorganic vapors into the bulk of the polymeric material, transforming it into an organic-inorganic hybrid material. The resultant hybrid materials are known to have properties that differ from their parent polymer. In this work, we examine the VPI of PMMA blocks with trimethylaluminum (TMA) vapors and water to form PMMA-AlOx hybrid materials. We study the effects of infiltration temperature, time, and number of cycles on the hardness of the material using a microhardness tester. Additionally, chemical changes to the composition and chemical structure of the material are studied with SEM-EDX analysis and FTIR spectroscopy.

The results of this experiment in Figure 1 show that when PMMA is infiltrated at 120 °C, hardness initially decreases and then steadily increases. We observe a decrease in Vickers' hardness from about 23.1 ± 0.6 to 10.9 ± 0.5 between the pure polymer and 3 hours of infiltration. The hardness then rises to 16.1 ± 0.2 after 10 hours of infiltration, which is still lower than the pure polymer. These results are surprising to us, given we nominally infiltrate the softer polymer material with a harder ceramic-like material. This phenomenon may be explained by chemical bond disruption in the hybrid that is softening the polymer upon infiltration. Additionally, there is visible chemical change in the sample, as they increase in amber color with longer hold times as shown in Figure 2. These chemical changes will be discussed more fully at my poster presentation.

Spectroscopic ellipsometry is a characterization technique used for analyzing the optical characteristics of high-k dielectric films in advanced semiconductor devices. Using the J.A. Woollam M-2000D spectroscopic ellipsometer, we characterized monolithic and nanolaminate dielectric layers composed of hafnium oxide, aluminum oxide, and silicon dioxide to investigate the relationship between film composition, structure, and dielectric performance. Through the utilization of Cauchy and B-spline fitting models, we extracted the refractive index and the extinction coefficient across ultraviolet to near-infrared wavelengths. We compared monolithic and nanolaminate dielectric film stacks to determine which configuration yielded the highest dielectric constant. Wafer mapping was used to reveal nonidealities and nonuniformities in the varying layer stacks across a 200 mm substrate. Results demonstrate that hafnium oxide and aluminum oxide nanolaminate structures exhibit the highest dielectric constants, and increased concentrations of aluminum oxide may further improve the dielectric constant. Our results provide crucial insight into thin-film dielectrics suitable for next-generation semiconductor devices.

Gastrointestinal (GI) disorders, such as inflammatory bowel disease (IBD), are commonly diagnosed using invasive endoscopy and biopsy. Ingestible capsules have emerged as a minimally invasive alternative for GI monitoring, sampling, and targeted drug delivery. As these pill-sized devices traverse different GI regions, localization becomes essential for interpreting measurements within the appropriate physiological context. Therefore, scalable and low-cost pH sensing solutions are desired to complement existing capsule size and electronics. This work presents the integration of an iridium oxide (IrO2) pH sensor into an ingestible capsule prototype for measuring dynamic pH gradients in GI environments to classify sensor readouts (Fig. S1).

The pH sensor consists of screen-printed electrode (SPE) with platinum (Pt) working and counter electrodes and a silver (Ag) reference electrode. An electrodeposition solution was prepared following existing protocols. Briefly, iridium chloride was dissolved in DI water (5.5 mM) and stirred for 30 minutes, followed by addition of 0.5 mL hydrogen peroxide and stirring for 10 minutes before adding 0.25 g oxalic acid. The solution was adjusted to pH 10.5 with potassium carbonate, heated under a water bath for 5h, then stored at 4 °C until use. Electrodeposition was performed using an Interface 1010E benchtop potentiostat (Fig. S2). The SPE was submerged in solution, within an ice-water bath, and the Pt working electrode was modified using either (1) chronopotentiometry (CP) at 0.2 mA/cm2 for 100 s or (2) cyclic voltammetry (CV) from 0 V to +0.7 V at 50 mV/sec for 90 cycles (Fig. S2b).

IrO2 film formation was characterized using open circuit potential (OCP) measurements in pH 4.00, 6.86, and 9.81 buffer solutions for 60 s (Fig. S3a). Calibration curves were generated for each electrodeposition method (Fig. S3a,b). Linear fitting yielded sensitivities of 71.25 mV/pH (R2 = 0.9861) for the CV-pH sensor and 65.07 mV/pH (R2 = 0.959) for the CP-pH sensor (Fig. S3b). Solution pH was verified using a commercial pH meter (Nanbei Instrument) prior to testing. Sensor drift was evaluated in pH 4.00 buffer solution for 30 minutes, yielding 2.36 and 28.80 mV/hr, respectively. This showed that the CV-pH sensors showed superior film formation and performance compared to the CP-pH sensor. This work further demonstrates the integration of the IrO2 sensor with a high-impedance voltage follower (LTC6078) and analog front-end (AD5940) into an existing ingestible capsule prototype (Fig. S3c), while implementing embedded on-chip calibration to improve signal fidelity, and evaluating performance in simulated gastric and intestinal fluids.

Advances in microelectromechanical (MEMS) research has enabled the development of non-invasive ingestible capsule devices for medical interventions in the gastrointestinal (GI) tract. Further ingestible device miniaturization is limited by the necessity for batteries to power them. Onboard energy harvesters present an alternative power method, reducing the footprint of the ingestible device. Gastric battery and chemical energy harvesters have shown promising results integrating into ingestible devices, but operation is limited to the stomach and prone to energy leakage. To overcome these limitations, we propose a hybrid energy harvesting system that enables chemical harvesting in the stomach and piezoelectric harvesting in the intestines, thereby extending the overall region of operation (Fig. S1).

Here, we report a piezoelectric energy harvester to convert mechanical, peristaltic motion within the intestines to electrical energy. The harvester utilizes polyvinylidene fluoride (PVDF) thin films, known for their excellent biocompatibility, flexibility, and piezoelectric properties. Multiple thin film configurations under controlled mechanical excitation were evaluated to maximize voltage output and prevent back charging between the PVDFs. Two thin films with isolated H-bridges had the highest voltage output of 85 mV (Fig. S2). Integration with an integrated circuit (IC) improved energy collection efficiency from the PVDFs by preventing premature voltage dissipation. Our findings support the feasibility of piezoelectric energy harvesting for microscale biomedical applications.

To facilitate testing, we are developing a simulated small intestinal model consisting of a silicone sleeve and actuators that apply a realistic pressure wave via an external pump to move the capsule prototype through the model (Fig. S3). Testing the piezoelectric harvester in the simulated model will enable characterization of voltage outputs from peristaltic forces in the microscale (18–62 mmHg). We anticipate the supplemental energy collection supplied from the piezoelectric harvester will counteract capacitor leakage and allow for a decrease in overall capsule size once scaled appropriately. Integrating the piezoelectric harvester with a chemical harvester will enable an ingestible self-powered system capable of sustained operation in the GI tract.

Advances in microelectromechanical (MEMS) research has enabled the development of non-invasive ingestible capsule devices for medical interventions in the gastrointestinal (GI) tract. Further ingestible device miniaturization is limited by the necessity for batteries to power them. Onboard energy harvesters present an alternative power method, reducing the footprint of the ingestible device. Gastric battery and chemical energy harvesters have shown promising results integrating into ingestible devices, but operation is limited to the stomach and prone to energy leakage. To overcome these limitations, we propose a hybrid energy harvesting system that enables chemical harvesting in the stomach and piezoelectric harvesting in the intestines, thereby extending the overall region of operation (Fig. S1). This work investigates the design trade-offs of electrochemical harvester electrodes for current generation within ingestible capsule form factors.

Previously reported chemical energy harvesters have been demonstrated, utilizing stomach acid to induce oxidation-reduction reactions, producing electric current that can be used to power an ingestible device. While these systems can generate electrical current, maintaining sufficient power output over the capsule’s residence time in the stomach remains a challenge. To address this limitation, this work integrates both piezoelectric and chemical energy harvesters; each system can be independently optimized for maximum power output within its respective operating region and duration. Thus, the chemical harvester seeks to maximize power for the amount of time the capsule will spend in the stomach.

Optimizing the power generation of the chemical harvester entailed material selection and evaluation of electrode dimensions and size. Anode and cathode materials were examined using galvanostatic discharge across a 1kΩ load with a benchtop potentiostat. Based on the average power density, the electrochemical cell comprises a magnesium (Mg) anode and molybdenum (Mo) cathode and was assembled on a thin polyimide film with 4 mm spacing (Fig. S2). Characterization of the Mg-Mo harvester at varied surface area (i.e., 8, 16, 24 and 32 mm2) in simulated gastric fluid revealed that power density increased with increasing electrode size (Table S3); however plateau at the 4 mm x 4 mm size anode/cathode, which produces 0.219 mW/mm. Integrating the chemical harvester with a piezoelectric harvester will enable an ingestible self-powered system capable of sustained operation in the GI tract.

Vanadium disulfide (VS₂), a member of the transition metal dichalcogenides (TMDs) family, has gained considerable attention from researchers owing to its remarkable properties. These include metal-insulator transition behavior, room-temperature ferromagnetism, a unique layered structure, and metallic conductivity. Additionally, VS₂ can form highly crystalline materials. With advances in achieving a more precise structure of this semiconducting material, VS₂ nanomaterials have the potential to be the most efficient TMDs for various photonic and optoelectronic applications. Chemical vapor deposition (CVD) has proven to be an effective method for synthesizing two-dimensional materials. Its simple process, compatibility with industry standards, and capacity to produce high-quality crystals make it an excellent choice for both researchers and industrial producers. This study will investigate the optoelectronic behavior of VS₂ thin films synthesized on different substrates using CVD, building on and extending conventional growth techniques. It will determine the optimal growth conditions, with particular attention to substrate type, growth temperature, and carrier gas flow rate. The properties of the resulting samples, including surface morphology, crystalline quality, Raman phonon modes, and bandgap characteristics, will be systematically studied as a function of substrate type, growth temperature, and carrier gas flow rate using Raman spectroscopy, photoluminescence (PL), and confocal laser scanning microscopy.

Electrochemical Protonation of ALD Oxide Thin Films

Kaydence Delgado, Daniel J. MacAyeal, Alexander C. Kozen

University of Vermont, Department of Physics

Hydrogen incorporation in ultra-thin atomic layer deposited (ALD) oxide films is important for understanding macroscale properties such as water diffusion barrier performance, dielectric behavior, chemical reactivity, and electrical breakdown strength, and, critically, suitability as a barrier material in fusion reactors. However, accurately measuring hydrogen content in films thinner than 10 nm remains difficult using conventional surface science techniques. An alternative approach is to use electrochemical ion insertion/extraction to quantify exchangeable protons in ALD-grown oxide films using an aqueous system. We investigate the protonation behavior of ALD oxide films (Al2O3, ZnO, and Nb2O5) growth with TMA, NbEtOH, and DEZ as metalorganic precursors and H2O, t-BuOH, and O3 as oxidation precursors, and discuss how differences in oxidation precursor selection impact protonation behavior in these oxide films. We examine electrochemical reactions with cyclic voltammetry and discuss how ALD film thickness and oxidation precursor selection affects electrochemical response, proton insertion behavior, and ion-transport kinetics using cyclic voltammetry. Lastly, we will use Dunn–Trasatti analysis to extract protonation redox kinetics, giving us insight into the relationship between ALD film thickness, transport behavior, and ion insertion/deinsertion kinetics.

Seed biopolymers, such as chickpeas, are commonly utilized in kitchens and are grown worldwide. Known for their great yield, health benefits, and versatility – agriculture and everyday suburbia depend on chickpeas. However, due to their thick outer cuticle structure, germination varies from seed to seed and results in a slow growth rate. As such, there is a desire to develop procedures that produce more consistent and faster germination processes. One potential method is the utilization of plasma-enhanced modification techniques. It has been suggested by surface analysis that the use of cold air plasma treatments will etch at the outer layer of the seed coat, inducing hydrophilicity. If this translates onto the chickpea biopolymer, germination should consequently be enhanced.

In order to achieve more reproducible etching processes, the mechanism driving the etching of the seed coat must be explored. Here, optical emission spectroscopy (OES) is used to monitor gas-phase species during chickpea treatment. A low-temperature, inductively-coupled plasma system formed from a mixture of breathing air and argon (90% and 10%, respectively, by pressure) is used for all treatment conditions, with the Ar serving as an actinometric addition. Various treatment times (30 - 120 s), pressures (50 - 250 mTorr), and applied powers (50 – 100 W) were assessed. Densities (measured via OES) were determined for plasma systems, with and without the chickpeas present, to help identify key reactive species and etch products. Notably, the presence of chickpeas increased the density of CO* gas while simultaneously reducing the density of NO*. These relationships help verify the predicted etching and break down of the hydrophobic cuticles. This is further explored by increasing the number of chickpeas present in the reactor, as well as further comparison with other conditions previously described. Etching into the hydrophilic cuticle as planned will allow for easier water access into the seed and higher consistency in the germination process.

Gold surfaces can change at the atomic level when they interact with different chemical species. In this study, we investigated how different acids and salts affect the surface reconstruction of Au(111) under ambient conditions using Scanning Tunneling Microscopy (STM). Different chemical solutions were deposited on the Au surface, which was then imaged with the STM. Acids and salts containing the same anion were compared to determine if the cation or anion had a greater effect on the Au(111) surface. Perchloric acid (HClO₄) and potassium perchlorate (KClO₄) produced similar surface reconstructions and finger-like gold structures, even though they contain different cations. Similar behavior was found with nitric acid and nitrate salts. These results suggest that the anion plays a larger role than the cation in Au(111) surface reconstruction, namely the formation of Au magic fingers. Anions that contained oxygen atoms also produced a greater surface disturbance than chloride. Perchlorate and phosphate anions showed the greatest surface reconstruction, nitrate showed less, and chloride produced the least. Growth-rate measurements supported these STM observations, with KClO₄ and HClO₄ producing the highest growth rates and KCl producing the lowest. Overall, these reactions suggest that the type of anion, especially oxygen-containing species, affects the movement of gold atoms and the reconstruction of Au(111). Future studies using X-ray Photoelectron Spectroscopy (XPS) and Density Functional Theory (DFT) will help determine how these chemical species interact with the Au(111) surface.

Understanding how water interacts with copper surfaces requires a sequential, step-by-step mapping of surface morphology as structural complexity is experimentally introduced. Using scanning tunneling microscopy (STM) and temperature programmed desorption (TPD), we track the structural evolution of the Cu(111) surface through five distinct phases of preparation. We begin with clean Cu(111), which exhibits atomically flat, pristine terraces separated by low-density step edges. Introducing oxygen to clean copper (0, 125, 250, and 500 L) drives structural phase transformations, evolving from simple step edges to the growth of triangular oxide domains and the nucleation of added oxide at higher coverages. Next, the underlying pristine framework is broken down via Ar+ ion sputtering at room temperature and 400 K, structurally engineering nanoscale pits. When oxygen is dosed onto these sputtered surfaces (125 L), the oxygen atoms preferentially attach to these newly formed step edges, altering the step edges into a “saw-tooth” appearance. Finally, we introduce water utilizing ultralow dosages (1.7E-3 ML) at 14 K. Water initially adsorbs as mostly isolated, dispersed species. Upon annealing to 50 K, these molecules undergo thermal migration, reorganizing structurally into distinct clusters (dimers and trimers) on Cu(111). Correlating this physical layout with TPD allows us to better understand the structure/reactivity relationship of these oxygen-modified Cu(111) surfaces. Future studies will investigate whether the water cluster configuration is governed by the morphology of the oxygen-defect domains.

The selective catalytic epoxidation of alkenes such as ethylene and propylene are major industrial processes worth $77 billion globally each year. Heterogeneous catalysts exhibit selectivity for epoxidation: Ag is selective for ethylene and Cu is selective for propylene. Both require the use of numerous promoters, some of which are toxic, and all of which contribute to complex catalytic systems that are difficult to understand. The use of Ag/Cu bimetallic surfaces has gained attention due to their ability to enhance epoxidation reactions without the need for promoters. The presence of Cu facilitates room temperature O₂ dissociation, which enables propylene oxidation. Meanwhile, Ag(111) does not oxidize easily; incorporating Cu helps to overcome the O₂ dissociation barrier. Temperature programmed desorption (TPD) experiments confirm that exposing water to the oxidized Cu surface allows the formation of chemisorbed hydroxyl entities. Dosing propylene on this hydroxylated Cu surface exhibits reactivity for propylene oxidation. TPD measurements reveal that this reactivity is observed only at specific propylene and water surface coverages. Investigating various silver coverages allows us to observe its role in propylene oxidation. Increasing amounts of Ag on Cu(111) inhibit the oxidation of propene, indicating that Ag acts as a capping agent on active Cu sites. These findings reveal that Ag coverage strongly influences alkene oxidation on Ag/Cu(111) by selectively capping active Cu sites and suppressing propylene oxidation. Understanding the distinct role of Ag provides insight into the design of more selective bimetallic oxidation catalysts.

Molecular beam epitaxy (MBE) is commonly used to grow materials such as single crystal thin films, multilayers, superlattices and nanostructures, for a diverse range of research applications in electronics and energy. The application of artificial intelligence (AI) can be used to increase efficiency during the growth of MBE films, and speed up material characterization. X-ray photoelectron spectroscopy (XPS) is a spectroscopic technique that can analyze the topmost layer of films to quantify the elemental composition of samples. A method of automating the analysis of XPS spectra is essential, as it can provide a post-growth metric to train a real-time, during-growth AI system that uses reflection high-energy electron diffraction (RHEED) to guide the growth of MBE films. In order to achieve this goal, a convolutional neural network (CNN) was trained on a dataset generated from XPS survey spectra including FeSe, SrIrO₃, and LaCoO₃ films. The design of the CNN was based on an existing model used to classify transition metal oxides [1], but modified to quantify elemental composition from more complex chalcogenide and oxide films. The reference spectra were labelled by their relative intensity of the selected elements by expert human quantification, and were then randomly linearly combined and transformed to generate the training dataset. The metrics collected about the performance of the different models trained show that the final model outperformed other models that used smaller binding energy ranges and alternative methods of dataset generation. Additionally, the testing procedures used by previous research was expanded upon by utilizing unseen XPS spectra, which the model was able to quantify very accurately compared to expert quantification. Future work will focus on incorporating additional spectra from new oxide and chalcogenide films grown, and those grown in the recently installed Scienta Omicron XPS system, increasing the model’s applicability to different compounds and systems. In conclusion, the convolutional neural network designed was able to quantify the elemental composition of different types of thin films, and will be utilized as a post-growth metric for a real-time model that aids in the growth of these films.

[1] Pielsticker, L. Anal. Chim. Acta, 2023, vol. 1271, p. 341433

The production of pollutant nitrogen oxides from combustion processes has led to significant environmental issues. Nitric oxide (NO) is of primary concern, as its presence in the atmosphere can contribute to environmental issues such as acid rain formation, groundwater contamination, and ozone depletion. The emission of NO has been significantly reduced through the implementation of three-way catalytic converters in combustion engines. However, the high cost of precious metals and inactivation due to sulfur contamination remain significant challenges. Plasma-assisted catalysis (PAC) is a promising approach for nitrogen oxide control that integrates plasma activation with traditional catalysis to utilize the advantages of both processes. Because the fundamental mechanisms governing these plasma-catalyst interactions remain unclear, developing a better understanding of the underlying chemistry involved in PAC is the focus of this work.

Our system consists of commercial γ-Al₂O₃ scaffolds impregnated with Ag and Ni, which are then exposed to plasmas formed from model exhaust gases. In previous work, steady-state diagnostic data has been compiled from the exposure of raw precious metals, alumina, and metal-doped alumina across a range of morphologies and catalysts designs to these plasmas. An inversely proportional relationship between NO density and NO vibrational temperature (T_V) was demonstrated, independent of the material present. Our current work has shown that plasmas generated from breathing air exhibit a lower range of NO densities and T_V (1930-5390 K) when compared to those previously measured in N₂/O₂ plasmas (2660-6330 K) with comparable catalysts present. Our goal is to investigate the discrepancies in observed data using time-resolved optical emission spectroscopy. This approach will help identify key diagnostic parameters associated with plasma-catalyst interactions, providing greater insight into the mechanisms responsible for the catalytic reduction of NO using PAC. Such efforts can contribute to the development of more effective exhaust treatment methods and the overall reliability of plasma-assisted catalysis.

Copper is used in a wide range of catalytic applications, such as selective epoxidation, however it easily overoxidizes reactants, leading to combustion. Adding Ag to Cu catalysts boosts epoxidation and minimizes combustion without promoters, yet the reactive oxygen species responsible for epoxidation on AgCu bimetallic catalysts are not well understood. Exploring atomic oxygen and hydroxyl species helps identify the reactive oxygen necessary for selective reactions on AgCu. To investigate adsorbed atomic oxygen and hydroxyl species, experiments were first conducted on a Cu(111) surface. Water desorbs molecularly from Cu(111) with zero-order kinetics and a Tdes = 145-157 K. To induce water dissociation, the surface was oxidized at room temperature, forming atomic O. Temperature–programmed desorption (TPD) experiments under ultrahigh vacuum show that atomic oxygen increases the desorption temperature of water by 12-15 K, stabilizing OH on the surface. The higher desorption temperature results from hydroxyl groups undergoing disproportionation. To explore the sites responsible for this increase, sputtered Cu(111) experiments were conducted. Cu(111) sputtered at room temperature created pits and islands with undercoordinated atoms. Atomic oxygen adsorbed at these defect sites, producing an increased TPD peak at ~221 K, indicating enhanced hydroxyl stabilization on the roughened surface. When Cu(111) was sputtered at 400 K, producing pits but fewer islands, the 221 K peak was suppressed. Adding Ag monolayers to oxidized Cu(111) decreased hydroxyl formation. These results suggest hydroxyl stabilization makes OH a viable reactive oxygen species for epoxidation on Cu(111) but not on Ag/Cu(111) catalysts.

Stress urinary incontinence (SUI) is a loss of bladder control during certain movements, often occurring after childbirth. This condition often results after vaginal delivery, leading to injury of the pudendal nerve (PN). Small amounts of electrical stimulation to this nerve have been shown to increase the rate of healing. However, there are no current devices on the market to electrically stimulate the pudendal nerve. We propose a small, implantable device for stimulation of the PN. This device uses flexible piezoelectric materials, which produce electricity under mechanical stress, stimulating the nerve. The device is also biodegradable, meaning only one surgery is needed for implantation.

To test the device’s electrical output, a force tester was developed, with a weight producing an impact force of 0.5N when dropped down a shaft. This allows for repeated tapping of the device to assess electrical output at the exposed leads using an oscilloscope. Second, the devices are implanted on rats, who are trained to run on a wheel to stimulate the device. To determine the activity of the rats, a counter box, which tracks the number of revolutions of the running wheel, was constructed. This circuit displays the number of revolutions and saves the timestamps of the data to a memory card, allowing for the speed of the wheel at any given time to be calculated.