Feasibility Study of the Flash-Sole: A Wearable Midsole With Soft Actuators for Walking Assistance (Flash-Sole)

Feasibility of Flash-Sole in Human Trials: An Active Midsole Powered by Stacked Dielectric Elastomer Actuators for Push-Off Assistance

The goal of this clinical trial is to test a new shoe device called Flash-Sole. The Flash-Sole is designed to help support the ankle while walking. It was developed by researchers at the University of Nebraska at Omaha. The device uses soft materials and electrical signals to gently assist with foot movement.

The main questions this study aims to answer are:

• Is the Flash-Sole safe to wear?
• Is it comfortable for users?
• Does it work as intended to assist walking? This study will include up to 15 healthy adults between the ages of 19 and 45. The Flash-Sole is considered investigational and is not approved by the U.S. Food and Drug Administration (FDA).

Participants will:

• Complete one visit at the Biomechanics Research Building that lasts about 2 hours
• Answer a few health questions to make sure they can join the study
• Do short walking trials wearing their own shoes
• Wear special shoes with the Flash-Sole device
• Walk short distances on a treadmill at a comfortable speed while the device is turned on and off
• Wear small, sticky sensors on their legs to measure movement and muscle activity
• Wear a safety harness to prevent falls
• Complete a short survey about how the shoes felt and how easy they were to use The purpose of this early study is to learn how the device performs and how people feel about wearing it. The results may help guide improvements to the device and inform future studies. This research is not testing whether the device helps people with walking problems yet, but it may lead to that kind of research in the future.

Study Overview

• Status: Not yet recruiting
• Conditions: Motor Function
• Intervention / Treatment: Device: Flash-Sole midsole device

Detailed Description

This study evaluates the feasibility, usability, and functional performance of the Flash-Sole, a novel wearable robotic midsole developed at the University of Nebraska at Omaha (UNO). The Flash-Sole is powered by stacked dielectric elastomer actuators and designed to provide gentle push-off assistance during walking. This early-stage trial focuses on determining whether the Flash-Sole system can be safely and comfortably worn by healthy adults and whether it functions as intended in a laboratory environment.

The study uses a single-session, within-subject design with up to 15 participants. Each participant will complete walking trials in both baseline conditions (standard shoes) and experimental conditions (Flash-Sole shoes with the system either active or inactive). The research will compare gait parameters and user feedback across these conditions. No control group or randomization is used, as this study is exploratory and not powered to assess clinical outcomes.

During the single session (~2 hours), participants will:

• Complete screening for eligibility
• Perform short walking tasks in standard shoes and Flash-Sole shoes
• Walk on a treadmill at a self-selected comfortable speed
• Wear surface EMG and IMU sensors to measure muscle activity and movement
• Provide subjective feedback via standardized usability questionnaires (e.g., System Usability Scale and QUEST 2.0) The primary outcomes of interest include system functionality (e.g., successful actuator activation), usability (System Usability Scale score), and user-reported comfort and ease of use (QUEST 2.0). Secondary outcomes include basic gait characteristics (e.g., cadence, step length) and participant-reported adverse effects, if any.

All walking trials will be short (approximately one minute per trial), conducted with rest breaks between trials as needed. A fall-prevention safety harness will be worn at all times. No investigational drugs or implanted devices are used. The Flash-Sole system is investigational and not approved by the U.S. FDA. The study is not conducted under an IDE.

Data will be analyzed using descriptive statistics to characterize usability, comfort, and functional performance metrics. Due to the small sample size and feasibility nature of the study, inferential statistics will be limited and exploratory only.

This study is intended to inform future device refinements and guide the development of subsequent clinical trials involving individuals with walking impairments, such as stroke survivors or children with cerebral palsy.

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Research Coordinator, PhD; Phone Number: 402-554-3228; Email: smohammadi@unomaha.edu

Study Locations

• United States
  • Nebraska
    • Omaha, Nebraska, United States, 68182
      • University of Nebraska at Omaha - Biomechanics Research Building
      • Contact: Research Coordinator; Phone Number: 402-554-3228; Email: smohammadi@unomaha.edu
      • Contact: Principal Investigator; Phone Number: 402-554-7525; Email: abehboodi@unomaha.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Age: 19 to 45 years old at the time of consent
2. Able to understand study procedures and provide informed consent
3. Able to walk independently without assistive devices
4. Willing to wear the Flash-Sole device and complete gait trials during a single session
5. Body weight under 80 kg to comply with device safety specifications

Exclusion Criteria:

1. Current or recent (within 6 months) lower-limb injury, surgery, or fracture
2. History of neurologic, musculoskeletal, or cardiovascular conditions affecting gait
3. Skin conditions, open wounds, or known allergies at the foot/ankle that interfere with device wear
4. Use of implanted electronic medical devices (e.g., pacemakers, neurostimulators)
5. Cognitive or language impairments that preclude informed consent or task participation
6. no medication related to musculoskeletal condition (e.g., pain relief medications or similar treatments) .

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Device Feasibility
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Flash-Sole Walking Evaluation; Participants will walk on a treadmill under two conditions: with the Flash-Sole device turned on (providing ankle assistance) and with the device turned off. This helps researchers compare walking performance and user experience between assisted and unassisted conditions.

Device: Flash-Sole midsole device; The Flash-Sole is a wearable robotic midsole powered by dielectric elastomer actuators (DEAs). It is embedded in custom footwear and designed to provide ankle push-off assistance during walking. The device operates in two modes: powered (assistance on) and unpowered (assistance off), allowing researchers to assess its mechanical support and user comfort in both states.; Other Names: Wearable robotic midsole, assistive midsole

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Successful Activation of Flash-Sole Device Across Timing Conditions	This measure assesses whether the Flash-Sole device can reliably detect late-stance gait phases and trigger actuator activation without malfunction. Gait-phase detection and actuation success will be quantified as the percentage of walking trials with accurate and timely device triggering during treadmill walking. Unit of Measure: Percentage of successful trials (%)	Day 1 (single-session, during each 1-minute walking trial)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Adverse Events and Device-Related Discomfort	Incidence of any device-related adverse events, including physical discomfort, perceived instability, tripping risk, or device malfunction. Events will be monitored throughout the session using observation and participant verbal reports. Unit of Measure: Number of events	Throughout the 2-hour study session on Day 1
Perceived Usability (System Usability Scale)	Participant-perceived usability of the Flash-Sole will be assessed using the System Usability Scale (SUS), a standardized 10-item instrument. Each item is scored on a 5-point Likert scale, producing a total score from 0 to 100. Higher scores reflect greater perceived usability. Unit of Measure: SUS Score (0-100; higher = better usability)	Immediately following the final walking trial on Day 1
Comfort and Satisfaction (QUEST 2.0)	Participant-perceived comfort and satisfaction with the Flash-Sole device will be evaluated using the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0). Items are rated on a 5-point scale from 1 (not satisfied at all) to 5 (very satisfied), with higher scores indicating greater satisfaction. Unit of Measure: QUEST 2.0 score (1-5 per item; higher = more satisfied)	Immediately following the final walking trial on Day 1

Collaborators and Investigators

• Sponsor: University of Nebraska
• Investigators: Principal Investigator: Ahad Behboo, University of Nebraska

Publications and helpful links

Helpful Links

• UNO Biomechanics Research Building

Study record dates

Study Major Dates

• Study Start (Estimated): July 15, 2026
• Primary Completion (Estimated): September 15, 2026
• Study Completion (Estimated): September 30, 2026

Study Registration Dates

• First Submitted: March 18, 2026
• First Submitted That Met QC Criteria: March 26, 2026
• First Posted (Actual): April 2, 2026

Study Record Updates

• Last Update Posted (Actual): April 2, 2026
• Last Update Submitted That Met QC Criteria: March 26, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Wearable Technology; Assistive Walking Device; Robotic Footwear; Gait Support
• Other Study ID Numbers: FLASHSOLE-PILOT-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: There is no plan to share individual participant data (IPD) collected in this study. This decision is due to the early-phase nature of the study and the limited sample size, which may increase the risk of re-identification despite de-identification efforts.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No