Biomedical Engineering and Bioengineering Commons^™

Biological Resurfacing In A Canine Model Of Hip Osteoarthritis, Bradley T. Estes, Masataka Enomoto, Franklin T. Moutos, Megan A. Carson, Jeffrey M. Toth, Peter Eggert, Jonathan Stallrich, Vincent P. Willard, Deborah J. Veis, Dianne Little, Farshid Guilak, B. Duncan X. Lascelles

Biomedical Engineering Faculty Research and Publications

Articular cartilage has unique load-bearing properties but has minimal capacity for intrinsic repair. Here, we used three-dimensional weaving, additive manufacturing, and autologous mesenchymal stem cells to create a tissue-engineered, bicomponent implant to restore hip function in a canine hip osteoarthritis model. This resorbable implant was specifically designed to function mechanically from the time of repair and to biologically integrate with native tissues for long-term restoration. A massive osteochondral lesion was created in the hip of skeletally mature hounds and repaired with the implant or left empty (control). Longitudinal outcome measures over 6 months demonstrated that the implant dogs returned to …

Continuous Myoelectric Prediction Of Future Ankle Angle And Moment Across Ambulation Conditions And Their Transitions, Erika V. Zabre-Gonzalez, Lara I. Riem, Philip A. Voglewede, Barbara Silver-Thorn, Sara R. Koehler-Mcnichols, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

A hallmark of human locomotion is that it continuously adapts to changes in the environment and predictively adjusts to changes in the terrain, both of which are major challenges to lower limb amputees due to the limitations in prostheses and control algorithms. Here, the ability of a single-network nonlinear autoregressive model to continuously predict future ankle kinematics and kinetics simultaneously across ambulation conditions using lower limb surface electromyography (EMG) signals was examined. Ankle plantarflexor and dorsiflexor EMG from ten healthy young adults were mapped to normal ranges of ankle angle and ankle moment during level overground walking, stair ascent, and …

Contributions Of Implicit And Explicit Memories To Sensorimotor Adaptation Of Movement Extent During Goal-Directed Reaching, Devon D. Lantagne, Leigh A. Mrotek, Rebecca Slick, Scott A. Beardsley, Danny G. Thomas, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

We examined how implicit and explicit memories contribute to sensorimotor adaptation of movement extent during goal-directed reaching. Twenty subjects grasped the handle of a horizontal planar robot that rendered spring-like resistance to movement. Subjects made rapid “out-and-back” reaches to capture a remembered visual target at the point of maximal reach extent. The robot’s resistance changed unpredictably between reaches, inducing target capture errors that subjects attempted to correct from one trial to the next. Each subject performed over 400 goal-directed reaching trials. Some trials were performed without concurrent visual cursor feedback of hand motion. Some trials required self-assessment of performance between …

Electroencephalography Resting-State Networks In People With Stroke, Dylan B. Snyder, Brian D. Schmit, Allison S. Hyngstrom, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Introduction

The purpose of this study was to characterize resting-state cortical networks in chronic stroke survivors using electroencephalography (EEG).

Methods

Electroencephalography data were collected from 14 chronic stroke and 11 neurologically intact participants while they were in a relaxed, resting state. EEG power was normalized to reduce bias and used as an indicator of network activity. Correlations of orthogonalized EEG activity were used as a measure of functional connectivity between cortical regions.

Results

We found reduced cortical activity and connectivity in the alpha (p < .05; p = .05) and beta (p < .05; p = .03) bands after stroke while connectivity …

Evaluation Of Visible Diffuse Reflectance Spectroscopy In Liver Tissue: Validation Of Tissue Saturations Using Extracorporeal Circulation, Stylianos Voulgarelis, Faraneh Fathi, Astrid G. Stucke, Kevin D. Daley, Joohyun Kim, Michael W. Zimmerman, Johhny C. Hong, Nicholas Starkey, Kenneth P. Allen, Bing Yu

Biomedical Engineering Faculty Research and Publications

Significance: Real-time information about oxygen delivery to the hepatic graft is important to direct care and diagnose vascular compromise in the immediate post-transplant period.

Aim: The current study was designed to determine the utility of visible diffuse reflectance spectroscopy (vis-DRS) for measuring liver tissue saturation in vivo.

Approach: A custom-built vis-DRS probe was calibrated using phantoms with hemoglobin (Hb) and polystyrene microspheres. Ex vivo (extracorporeal circulation) and in vivo protocols were used in a swine model (n=15) with validation via blood gas analysis.

Results: In vivo absorption and scattering measured by vis-DRS with and without biliverdin …

Enhancing Reproductive Organ Segmentation In Pediatric Ct Via Adversarial Learning, Chi Nok Enoch Kan, Taly Gilat-Schmidt, Dong Hye Ye

Biomedical Engineering Faculty Research and Publications

Accurately segmenting organs in abdominal computed tomography (CT) scans is crucial for clinical applications such as pre-operative planning and dose estimation. With the recent advent of deep learning algorithms, many robust frameworks have been proposed for organ segmentation in abdominal CT images. However, many of these frameworks require large amounts of training data in order to achieve high segmentation accuracy. Pediatric abdominal CT images containing reproductive organs are particularly hard to obtain since these organs are extremely sensitive to ionizing radiation. Hence, it is extremely challenging to train automatic segmentation algorithms on organs such as the uterus and the prostate. …

Somatosensory Deafferentation Reveals Lateralized Roles Of Proprioception In Feedback And Adaptive Feedforward Control Of Movement And Posture, S.A.L. Jayasinghe, F. R. Sarlegna, Robert A. Scheidt, R. L. Sainburg

Biomedical Engineering Faculty Research and Publications

Proprioception provides crucial information necessary for determining limb position and movement, and plausibly also for updating internal models that might underlie the control of movement and posture. Seminal studies of upper-limb movements in individuals living with chronic, large fiber deafferentation have provided evidence for the role of proprioceptive information in the hypothetical formation and maintenance of internal models to produce accurate motor commands. Vision also contributes to sensorimotor functions but cannot fully compensate for proprioceptive deficits. More recent work has shown that posture and movement control processes are lateralized in the brain, and that proprioception plays a fundamental role in …

Changes In Cerebral Volume And White Matter Integrity In Adults On Hemodialysis And Relationship To Cognitive Function, W. T. Richerson, L. G. Umfleet, Brian D. Schmit, D. F. Wolfgram

Biomedical Engineering Faculty Research and Publications

Introduction: Patients on hemodialysis (HD) have a significant burden of cognitive impairment. Characterizing the cerebral structural changes in HD patients compared to healthy controls and evaluating the relationship of cerebral structural integrity with cognitive performance in HD patients can help clarify the pathophysiology of the cognitive impairment in HD patients. Methods: In this cross-sectional study, in-center HD patients ≥50 years of age underwent brain structural and diffusion MRIs and cognitive assessment using the NIH Toolbox cognition battery. The cerebral imaging measures of the HD participants were compared to imaging from age-matched controls. Gray matter volume, white matter volume, and white …

Identifying Alternate Resources And Adjusting Expectations For Senior Design Projects During The Covid-19 Pandemic Of 2020, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

In March 2020, the COVID-19 pandemic required capstone design course instructors to transition to online learning. Student project teams were denied access to resources needed to construct and test prototypes scheduled to be delivered to project sponsors and clients at the end of the semester. Face-to-face collaboration was replaced with virtual team meetings. At Marquette University, efforts to identify (1) barriers to completing projects, (2) potential alternate prototyping resources, (3) adjustments to expectations of teams, and (4) changes to course deliverable requirements were completed. The results of these activities, the thought process used to guide students through the search for …

Prediction Of Emg Activation Profiles From Gait Kinematics And Kinetics During Multiple Terrains, Erika V. Zabre-Gonzalez, Diego Amieva-Alvarado, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Continuous myoelectric prediction of intended limb dynamics has the ability to provide transparent control of a prosthesis by the user. However, the impact on these models of adding a human user into the control loop is less clear. Here, the ability of a User Response Model (URM) to continuously predict EMG activity from gait kinematics and kinetics collected during three mobility tasks (level-ground walking, stair ascent, and stair descent) was examined. Multiple-input, multiple-output NARX-based URMs were developed with two outputs (ankle plantarflexor and dorsiflexor) and variable inputs (ankle kinetics, and shank and/or ankle kinematics). Accuracy in predicting the tibialis anterior …

Real-Time Optical Monitoring Of Endotracheal Tube Displacement, Ramzan Ullah, Karl Doerfer, Pawjai Khampang, Faraneh Fathi, Wenzhou Hong, Joseph E. Kerschner, Bing Yu

Biomedical Engineering Faculty Research and Publications

Proper ventilation of a patient with an endotracheal tube (ETT) requires proper placement of the ETT. We present a sensitive, noninvasive, operator-free, and cost-effective optical sensor, called Opt-ETT, for the real-time assessment of ETT placement and alerting of the clinical care team should the ETT become displaced. The Opt-ETT uses a side-firing optical fiber, a near-infrared light-emitting diode, two photodetectors with an integrated amplifier, an Arduino board, and a computer loaded with a custom LabVIEW program to monitor the position of the endotracheal tube inside the windpipe. The Opt-ETT generates a visual and audible warning if the tube moves over …

Association Of Liver Tissue Optical Properties And Thermal Damage, Vivek K. Nagarajan, Jerrold M. Ward, Bing Yu

Biomedical Engineering Faculty Research and Publications

Background and Objectives

Complete thermocoagulation of tumors is vital to minimize the risk of local tumor recurrence after a thermal ablation. Histological assessments are not real-time and require experienced pathologists to grade the thermal damage (histopathology) [Correction added on 21 January, 2020 after first online publication: After thermal damage in the preceding sentence, (histopathology) was added]. Real-time assessment of thermal tissue damage during an ablation is necessary to achieve optimal tumor ablation. In our previous studies, we found that continuous monitoring of the wavelength-averaged (435–630 nm) tissue absorption coefficient (µ_a) and the reduced scattering coefficient () during …

The Effect Of Discrete Visual Perturbations On Balance Control During Gait, Lara I. Riem, Brian D. Schmit, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Immersive virtual reality provides a safe and costeffective approach to administrating balance disruption during ambulation. Previous research has explored the effects of applying continuous perturbations in a virtual environment to challenge balance. This pilot study investigates the ability to disrupt balance with discrete visual perturbations during ambulation in healthy young adults. During the study participants walked on a treadmill within a virtual environment. As they walked the entire visual scene was intermittently shifted to the left or right 1 meter over 1 second. The results demonstrate a significant decrease in step length (𝑝 <; 0.05) and change in center of mass excursion (𝑝 <; 0.05) across participants (𝑁=13). Changes in gait lasted up to three steps after application, suggesting a consistent challenge to dynamic balance control as a result of the discrete visual perturbation. Further, participants did not demonstrate a reduction in response to the discrete visual perturbation with repeated exposure. The results indicate that discrete visual perturbations of a virtual scene can be used to challenge gait and modulate center of mass sway. The use of visual perturbations within a virtual environment to challenge dynamic balance could provide a safer and more affordable avenue for balance rehabilitation by reducing the need for systems that physically perturb balance.

The Neural Foundations Of Handedness: Insights From A Rare Case Of Deafferentation, S.A.L. Jayasinghe, F. R. Sarlegna, Robert A. Scheidt, R. L. Sainburg

Biomedical Engineering Faculty Research and Publications

The role of proprioceptive feedback on motor lateralization remains unclear. We asked whether motor lateralization is dependent on proprioceptive feedback by examining a rare case of proprioceptive deafferentation (GL). Motor lateralization is thought to arise from asymmetries in neural organization, particularly at the cortical level. For example, we have previously provided evidence that the left hemisphere mediates optimal motor control that allows execution of smooth and efficient arm trajectories, while the right hemisphere mediates impedance control that can achieve stable and accurate final arm postures. The role of proprioception in both of these processes has previously been demonstrated empirically, bringing …

Task-Specific Versus Impairment-Based Training On Locomotor Performance In Individuals With Chronic Spinal Cord Injury: A Randomized Crossover Study, Jennifer K. Lotter, Christopher E. Henderson, Abby Plawecki, Molly E. Holthus, Emily H. Lucas, Marzieh M. Ardestani, Brian D. Schmit, George Hornby

Biomedical Engineering Faculty Research and Publications

Background. Many research studies attempting to improve locomotor function following motor incomplete spinal cord injury (iSCI) focus on providing stepping practice. However, observational studies of physical therapy strategies suggest the amount of stepping practice during clinical rehabilitation is limited; rather, many interventions focus on mitigating impairments underlying walking dysfunction. Objective. The purpose of this blinded-assessor randomized trial was to evaluate the effects of task-specific versus impairment-based interventions on walking outcomes in individuals with iSCI. Methods. Using a crossover design, ambulatory participants with iSCI >1-year duration performed either task-specific (upright stepping) or impairment-based training for up to 20 sessions over ≤6 …

Indirect Structural Connectivity As A Biomarker For Stroke Motor Recovery, Miguel Renato Sotelo Munoz

Dissertations (1934 -)

In this dissertation project, we demonstrated that diffusion magnetic resonance imaging and measures of indirect structural brain connectivity are sensitive to changes in fiber integrity and connectivity to remote regions in the brain after stroke. Our results revealed new insights into the effects local lesions have on global connectivity—in particular, the cerebellum—and how these changes in connectivity and integrity relate to motor impairment. We tested this methodology on two stroke groups—subacute and chronic—and were able to show that indirect connectivity is sensitive to differences in connectivity during stroke recovery. Our work can inform clinical methods for rehabilitating motor function in …

Reaching Performance In Heathy Individuals And Stroke Survivors Improves After Practice With Vibrotactile State Feedback, Valay A. Shah

Dissertations (1934 -)

Stroke causes deficits of cognition, motor, and/or somatosensory functions. These deficits degrade the capability to perform activities of daily living (ADLs). Many research investigations have focused on mitigating the motor deficits of stroke through motor rehabilitation. However, somatosensory deficits are common and may contribute importantly to impairments in the control of functional arm movement. This dissertation advances the goal of promoting functional motor recovery after stroke by investigating the use of a vibrotactile feedback (VTF) body-machine interface (BMI). The VTF BMI is intended to improve control of the contralesional arm of stroke survivors by delivering supplemental limb-state feedback to the …

Patient-Specific Modeling Of Altered Coronary Artery Hemodynamics To Predict Morbidity In Patients With Anomalous Origin Of A Coronary Artery, Atefeh Razavi

Dissertations (1934 -)

Anomalous aortic origin of a coronary artery (AAOCA) is a condition where a coronary artery arises from the opposite aortic sinus, often with acute angle of origin (AO). AAOCA is associated with ischemia.1 This is especially concerning when the anomalous coronary artery takes an intramural course within the aortic wall, creating the potential for distortion or compression. Unroofing surgery replaces a restrictive ostium and intramural segment with a large ostium from the appropriate sinus and aims to create a less acute AO. Although these anatomical features may alter coronary artery blood flow patterns, hemodynamic indices such as time averaged wall …

Eeg Characterization Of Sensorimotor Networks: Implications In Stroke, Dylan Blake Snyder

Dissertations (1934 -)

The purpose of this dissertation was to use electroencephalography (EEG) to characterize sensorimotor networks and examine the effects of stroke on sensorimotor networks. Sensorimotor networks play an essential role in completion of everyday tasks, and when damaged, as in stroke survivors, the successful completion of seemingly simple motor tasks becomes fantasy. When sensorimotor networks are impaired as a result of stroke, varying degrees of sensorimotor deficits emerge, most often including loss of sensation and difficulty generating upper extremity movements. Although sensory therapies, such as the application of tendon vibration, have been shown to reduce the sensorimotor deficits after stroke, the …

Characterization Of Neuroimage Coupling Between Eeg And Fmri Using Within-Subject Joint Independent Component Analysis, Nicholas Heugel

Dissertations (1934 -)

The purpose of this dissertation was to apply joint independent component analysis (jICA) to electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to characterize the neuroimage coupling between the two modalities. EEG and fMRI are complimentary imaging techniques which have been used in conjunction to investigate neural activity. Understanding how these two imaging modalities relate to each other not only enables better multimodal analysis, but also has clinical implications as well. In particular, Alzheimer’s, Parkinson’s, hypertension, and ischemic stroke are all known to impact the cerebral blood flow, and by extension alter the relationship between EEG and fMRI. By characterizing …

Cone Identification In Choroideremia: Repeatability, Reliability, And Automation Through Use Of A Convolutional Neural Network, Jessica I.W. Morgan, Min Chen, Andrew M. Huang, Yu You Jiang, Robert F. Cooper

Biomedical Engineering Faculty Research and Publications

Purpose: Adaptive optics imaging has enabled the visualization of photoreceptors both in health and disease. However, there remains a need for automated accurate cone photoreceptor identification in images of disease. Here, we apply an open-source convolutional neural network (CNN) to automatically identify cones in images of choroideremia (CHM). We further compare the results to the repeatability and reliability of manual cone identifications in CHM.

Methods: We used split-detection adaptive optics scanning laser ophthalmoscopy to image the inner segment cone mosaic of 17 patients with CHM. Cones were manually identified twice by one experienced grader and once by two …

Deep Uv Fluorescence Scanning Microscopy For Breast Tumor Margin Detection, Tongtong Lu, Julie M. Jorns, Mollie Patton, Renee Fisher, Amanda Emmrich, Todd Doehring, Taly Gilat-Schmidt, Dong Hye Ye, Tina Yen, Bing Yu

Biomedical Engineering Faculty Research and Publications

Breast cancer is the most commonly diagnosed cancer among women. Positive margin status after breast-conserving surgery (BCS) is a predictor of higher rates of local recurrence. Intraoperative margin detection helps to complete tumor excision at the first operation. A margin tool that is capable of imaging all six margins of large lumpectomy specimens with both high resolution and fast speed (within 20 min) is yet to be developed. Deep UV light allows simultaneous excitation of multiple fluorophores and generating surface fluorescence images. We have developed a deep UV fluorescence scanning microscope (DUV-FSM) for slide-free, high-resolution and rapid examination of tumor …

Rapid Assessment Of Breast Tumor Margins Using Deep Ultraviolet Fluorescence Scanning Microscopy, Tongtong Lu, Julie M. Jorns, Mollie Patton, Renee Fisher, Amanda Emmerich, Todd Doehring, Taly Gilat-Schmidt, Dong Hye Ye, Tina Yen, Bing Yu

Biomedical Engineering Faculty Research and Publications

Significance: Re-excision rates for women with invasive breast cancer undergoing breast conserving surgery (or lumpectomy) have decreased in the past decade but remain substantial. This is mainly due to the inability to assess the entire surface of an excised lumpectomy specimen efficiently and accurately during surgery.

Aim: The goal of this study was to develop a deep-ultraviolet scanning fluorescence microscope (DUV-FSM) that can be used to accurately and rapidly detect cancer cells on the surface of excised breast tissue.

Approach: A DUV-FSM was used to image the surfaces of 47 (31 malignant and 16 normal/benign) fresh breast tissue samples stained …

A Size‐Modified Poisson–Boltzmann Ion Channel Model In A Solvent Of Multiple Ionic Species: Application To Voltage‐Dependent Anion Channel, Dexuan Xie, Said H. Audi, Ranjan K. Dash

Biomedical Engineering Faculty Research and Publications

We present a new size‐modified Poisson–Boltzmann ion channel (SMPBIC) model and use it to calculate the electrostatic potential, ionic concentrations, and electrostatic solvation free energy for a voltage‐dependent anion channel (VDAC) on a biological membrane in a solution mixture of multiple ionic species. In particular, the new SMPBIC model adopts a membrane surface charge density and a natural Neumann boundary condition to reflect the charge effect of the membrane on the electrostatics of VDAC. To avoid the singularity difficulties caused by the atomic charges of VDAC, the new SMPBIC model is split into three submodels such that the solution of …

Method For Spatial Overlap Estimation Of Electroencephalography And Functional Magnetic Resonance Imaging Responses, N. Heugel, E. Liebenthal, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Background

Simultaneous functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) measurements may represent activity from partially divergent neural sources, but this factor is seldom modeled in fMRI-EEG data integration.

New method

This paper proposes an approach to estimate the spatial overlap between sources of activity measured simultaneously with fMRI and EEG. Following the extraction of task-related activity, the key steps include, 1) distributed source reconstruction of the task-related ERP activity (ERP source model), 2) transformation of fMRI activity to the ERP spatial scale by forward modelling of the scalp potential field distribution and backward source reconstruction (fMRI source simulation) …

An Evaluation Of The Host Response To An Interspinous Process Device Based On A Series Of Spine Explants: Device For Intervertebral Assisted Motion (Diam®), Jeffrey M. Toth, Justin D. Bric

Biomedical Engineering Faculty Research and Publications

Background:

The objective of this study was to evaluate the host response to an interspinous process device [Device for Intervertebral Assisted Motion (DIAM®)] based on a series of nine spine explants with a mean post-operative explant time of 35 months.

Methods:

Explanted periprosthetic tissues were processed for histology and stained with H&E, Wright-Giemsa stain, and Oil Red O. Brightfield and polarized light microscopy were used to evaluate the host response to the device and the resultant particulate debris. The host response was graded per ASTM F981-04. Quantitative histomorphometry was used to characterize particle size, shape, and area per ASTM F1877-05. …

Role Of The Cortex In Visuomotor Control Of Arm Stability, Dylan B. Snyder, Scott A. Beardsley, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

Whereas numerous motor control theories describe the control of arm trajectory during reach, the control of stabilization in a constant arm position (i.e., visuomotor control of arm posture) is less clear. Three potential mechanisms have been proposed for visuomotor control of arm posture: 1) increased impedance of the arm through co-contraction of antagonistic muscles, 2) corrective muscle activity via spinal/supraspinal reflex circuits, and/or 3) intermittent voluntary corrections to errors in position. We examined the cortical mechanisms of visuomotor control of arm posture and tested the hypothesis that cortical error networks contribute to arm stabilization. We collected electroencephalography …

Pharmacokinetics Of 99mTc-Hmpao In Isolated Perfused Rat Lungs, Anne V. Clough, Katherine Barry, Benjamin Michael Rizzo, Elizabeth R. Jacobs, Said H. Audi

Biomedical Engineering Faculty Research and Publications

Lung uptake of technetium-labeled hexamethylpropyleneamine oxime (HMPAO) increases in rat models of human acute lung injury, consistent with increases in lung tissue glutathione (GSH). Since ^99mTc-HMPAO uptake is the net result of multiple cellular and vascular processes, the objective was to develop an approach to investigate the pharmacokinetics of ^99mTc-HMPAO uptake in isolated perfused rat lungs. Lungs of anesthetized rats were excised and connected to a ventilation-perfusion system. ^99mTc-HMPAO (56 MBq) was injected into the pulmonary arterial cannula, a time sequence of images was acquired, and lung time-activity curves were constructed. Imaging was repeated with a range …

A Dual-Modality Smartphone Microendoscope For Quantifying The Physiological And Morphological Properties Of Epithelial Tissues, Xiangqian Hong, Tongtong Lu, Liam Fruzyna, Bing Yu

Biomedical Engineering Faculty Research and Publications

We report a nonconcurrent dual-modality fiber-optic microendoscope (named SmartME) that integrates quantitative diffuse reflectance spectroscopy (DRS) and high-resolution fluorescence imaging (FLI) into a smartphone platform. The FLI module has a spatial resolution of ~3.5 µm, which allows the determination of the nuclear-cytoplasmic ratio (N/C) of epithelial tissues. The DRS has a spectral resolution of ~2 nm and can measure the total hemoglobin concentration (THC) and scattering properties of epithelial tissues with mean errors of 4.7% and 6.9%, respectively, which are comparable to the errors achieved with a benchtop spectrometer. Our preliminary in vivo studies from a single healthy human subject …

Vibration Propagation On The Skin Of The Arm, Valay A. Shah, Maura Casadio, Robert A. Scheidt, Leigh A. Mrotek

Biomedical Engineering Faculty Research and Publications

Vibrotactile interfaces are an inexpensive and non-invasive way to provide performance feedback to body-machine interface users. Interfaces for the upper extremity have utilized a multi-channel approach using an array of vibration motors placed on the upper extremity. However, for successful perception of multi-channel vibrotactile feedback on the arm, we need to account for vibration propagation across the skin. If two stimuli are delivered within a small distance, mechanical propagation of vibration can lead to inaccurate perception of the distinct vibrotactile stimuli. This study sought to characterize vibration propagation across the hairy skin of the forearm. We characterized vibration propagation by …