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

Official title

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

Overview

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.

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.

Interventions

• 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.

Primary outcome measures

• Successful Activation of Flash-Sole Device Across Timing Conditions [Time frame: Day 1 (single-session, during each 1-minute walking trial)]

Secondary outcome measures (3)

• Adverse Events and Device-Related Discomfort [Time frame: Throughout the 2-hour study session on Day 1]
• Perceived Usability (System Usability Scale) [Time frame: Immediately following the final walking trial on Day 1]
• Comfort and Satisfaction (QUEST 2.0) [Time frame: Immediately following the final walking trial on Day 1]

Eligibility criteria

Inclusion criteria

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

Exclusion criteria

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

N/A

Model

Single group

Masking

Open label

Primary purpose

Device feasibility

Study locations

United States · 1 center

• University of Nebraska at Omaha - Biomechanics Research Building — Omaha

Identifiers

NCT: NCT07507006 · FLASHSOLE-PILOT-01

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗