Engineering Commons^™

Electrically-Evoked Referred Sensations Induce Embodiment Of Rubber Limb, Anthony Nguyen, Brooke Draggoo, Brooklyn Tobias, Payton Dubose, Katharine Polasek

Faculty Publications

Introduction: Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, the quality of referred sensations evoked using surface electrical stimulation was evaluated using the rubber hand and foot illusions.

Methods: The rubber hand and foot illusions were attempted under 4 conditions: (1) multi-location tapping; (2) one-location tapping; (3) electrical stimulation of sensation referred to the hand or foot; (4) asynchronous control. The strength of each illusion was quantified using a questionnaire and proprioceptive drift, where a stronger response suggested embodiment of the rubber limb.

Results: 45 able-bodied individuals and two individuals with amputations participated in …

Tuned Photomechanical Switching Of Laterally Constrained Arches, Matthew L. Smith, J Gao, A A. Skandani, N Deering, D H. Wang, A A. Sicard, M Plaver, L-S Tan, T J. White, M R. Shankar

Faculty Publications

Laterally constrained arches driven between stable states by light, represent a unique space for compliant mechanism design. Exploiting mechanical multistability can overcome limitations of functional photomechanical actuators, which include limited repeatability, actuation speed, and positioning characteristics. Here, the addition of lateral constraints to an elastic bistable arch system is proposed as a method for toggling between bifurcated states by controlling the location of actinic irradiation. This approach expands the design space for photomechanical, mutistable structures and actuators. Arch behavior as a function of system parameters is simulated, including conditions leading to multistability. An experimental demonstration and exploration of a constrained …

Reactions At Noble Metal Contacts With Methylammonium Lead Triiodide Perovskites: Role Of Underpotential Deposition And Electrochemistry, Ross A. Kerner, Philip Schulz, Jeffrey A. Christians, Sean P. Dunfield, Benjia Dou, Lianfeng Zhao, Glenn Teeter, Joseph J. Berry, Barry P. Rand

Faculty Publications

Chemical reactivity of halide perovskites coupled with a low energy of formation makes it a challenge to characterize material properties and achieve long-term device stability. In this study, we elucidate electrochemical reactions occurring at the methylammonium lead triiodide (MAPbI₃)/Au interface. X-ray photoemission spectroscopy is used to identify a type of reduction/oxidation reaction termed underpotential deposition (UPD) involving lead, iodine, and hydrogen occurring at interfaces with noble metals. Changes in surface compositions and oxidation states suggest that UPD derived adsorbates at MAPbI₃/Au interfaces lower the energy barrier for release of volatile HI and/or I₂catalyzing degradation …

Bio-Inspired Sensing And Actuating Architectures For Feedback Control Of Civil Structures, Courtney A. Peckens, I. Cook, C. Fogg

Faculty Publications

Civil structures, such as buildings and bridges, are constantly at risk of failure due to external environmental loads, such as earthquakes or strong winds. To minimize the effects of these loads, active feedback control systems have been proposed but such systems still face numerous challenges which impede their widespread adoption. In order to overcome many of these challenges, inspiration can be drawn from the signal processing and actuating techniques employed by the biological central nervous system to develop a bio-inspired control algorithm. In this study the front-end, signal processing techniques employed by biological sensory systems, and in particular the mammalian …

Substrate-Dependent Photoconductivity Dynamics In A High-Efficiency Hybrid Perovskite Alloy, Ali Moeed Tirmzi, Jeffrey A. Christians, Ryan P. Dwyer, David T. Moore, John A. Marohn

Faculty Publications

Films of (FA_0.79MA_0.16Cs_0.05)_0.97Pb(I_0.84Br_0.16)_2.97 were grown over TiO₂, SnO₂, indium tin oxide (ITO), and NiO. Film conductivity was interrogated by measuring the in-phase and out-of-phase forces acting between the film and a charged microcantilever. We followed the films’ conductivity versus time, frequency, light intensity, and temperature (233−312 K). Perovskite conductivity was high and light-independent over ITO and NiO. Over TiO₂ and SnO₂, the conductivity was low in the dark,increased with light intensity, and persisted for 10’s of seconds after the light …

Doping Strategies For Small Molecule Organic Hole-Transport Materials: Impacts On Perovskite Solar Cell Performance And Stability, Tracy H. Schloemer, Jeffrey A. Christians, Joseph M. Luther, Alan Sellinger

Faculty Publications

Hybrid organic/inorganic perovskite solar cells (PSCs) have dramatically changed the landscape of the solar research community over the past decade, but >25 year stability is likely required if they are to make the same impact in commercial photovoltaics and power generation more broadly. While every layer of a PSC has been shown to impact its durability in power output, the hole-transport layer (HTL) is critical for several reasons: (1) it is in direct contact with the perovskite layer, (2) it often contains mobile ions, like Li+ – which in this case are hygroscopic, and (3) it usually has the lowest …

Wireless Sensor Networks For Long-Term Monitoring Of Urban Noise, Courtney Peckens, Cédric Porter, Taylor Rink

Faculty Publications

Noise pollution in urban environments is becoming increasingly common and it has potential to negatively impact people’s health and decrease overall productivity. In order to alleviate these effects, it is important to better quantify noise patterns and levels through data collection and analysis. Wireless sensor networks offer a method for achieving this with a higher level of granularity than traditional handheld devices. In this study, a wireless sensing unit (WSU) was developed that possesses the same functionality as a handheld sound level meter. The WSU is comprised of a microcontroller unit that enables on-board computations, a wireless transceiver that uses …

A Model Of Motor And Sensory Axon Activation In The Median Nerve Using Surface Electrical Stimulation, Jessica L. Gaines, Kathleen E. Finn, Julia P. Slopsema, Lane A. Heyboer, Katharine H. Polasek

Faculty Publications

Surface electrical stimulation has the potential to be a powerful and non-invasive treatment for a variety of medical conditions but currently it is difficult to obtain consistent evoked responses. A viable clinical system must be able to adapt to variations in individuals to produce repeatable results. To more fully study the effect of these variations without performing exhaustive testing on human subjects, a system of computer models was created to predict motor and sensory axon activation in the median nerve due to surface electrical stimulation at the elbow. An anatomically-based finite element model of the arm was built to accurately …

Natural Sensations Evoked In Distal Extremities Using Surface Electrical Stimulation, Julia P. Slopsema, John M. Boss, Lane A. Heyboer, Carson M. Tobias, Brooke P. Draggoo, Kathleen E. Finn, Payton J. Hoff, Katharine H. Polasek

Faculty Publications

Background: Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, surface electrical stimulation was evaluated as a method to non-invasively target a neural function, specifically natural sensation in the distal limbs.

Method: Electrodes were placed over the median and ulnar nerves at the elbow and the common peroneal and lateral sural cutaneous nerves at the knee. Strength-duration curves for sensation were compared between nerves. The location, modality, and intensity of each sensation were also analyzed. In an effort to evoke natural sensations, several patterned waveforms were evaluated.

Results: Distal sensation was obtained in all but …

Engineering Design And Gifted Pedagogy, Eric L. Mann, Rebecca L. Mann

Faculty Publications

No abstract provided.