Designing a Wearable, Centimeter-Scale Generator Powered by Human Movement

Wearable devices used in both research and industry require frequent recharg-ing. Typically, a device must be removed and charged separately, which reduces the device’s overall utility, especially if its primary function is for applications requiring continuous monitoring or actuation. To address this challenge, this work presents a compliant, centimeter-scale energy harvesting system that con- verts stored pneumatic energy via human movement into electricity intended to recharge a battery. The system design uses human footstrikes to pump air into an on-body pneumatic storage pouch. The released air then drives an axial flux induction generator, producing a maximum open circuit voltage of 3.89 Volts (V) and maintaining 2 V for over 38 seconds at a pouch pressure of 19.5 pounds per square inch absolute (psia). The generator’s design is guided by a mathe- matical model derived from Faraday’s Law along with magnetic field simula- tions in Ansys Maxwell. During the design process, emphasis was placed on wearability, form factor minimization, and fabrication using non-specialized, rapid-prototyping techniques. All structural components outside of the mag- nets, ball bearings, and center shaft are fabricated from compliant materials to enhance user comfort and device durability. The system is characterized across a range of pouch pressures and wall supply flowrates where a flowrate of 10 liters per minute (lpm) produced a maximum RMS output power of 34.7 milli- watts (mW) and a RMS voltage of 2.76 V. At this flowrate, the device outputs 12.6 milliamps (mA) which can trickle charge a 1.2 V nickel cadmium (NiCD) or nickel–metal hydride (NiMH) battery. While the generator’s pneumatic to electric power efficiency is approximately 0.73%, the current prototype’s out- put power, simplified fabrication techniques, and wearability demonstrate the feasibility of this system as a self-contained, human-powered, passive energy solution for low-power wearable electronics.

Name thesis:degree_name

M.S., Mechanical Engineering

Level thesis:degree_level

Master of Science

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

Cornell University

Year dc:date.issued

2025

Author dc:creator

• Simmons, Devin

Committee member dc:contributor.committeemember

• Helbling, Elizabeth

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

DOI

https://doi.org/10.7298/ttkp-9p04

Dc Identifier Other

ProQuest Submission ID: 12578
ProQuest Publication ID: 32171204

OAI identifier oai:identifier

oai:ecommons.cornell.edu:1813/120652