11/11/2026
By Thomas Dugan

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a doctoral dissertation defense by Cuilei Li, titled “Design, Fabrication, and Integration of Flexible Thermoelectric Systems for Wearable Thermal Management.”

Details

  • Date: Friday, Nov. 20, 2026
  • Time: 10 a.m. – noon
  • Location: ETIC 245

Committee members

  • Zhiyong Gu, Advisor, Professor and Department Chair, Chemical Engineering, UMass Lowell
  • Nese Orbey, Professor and Associate Chair, Chemical Engineering, UMass Lowell
  • Ramaswamy Nagarajan, Co-Director of HEROES and Distinguished University Professor, Plastics Engineering, UMass Lowell
  • Edward Fratto, Ph.D., Postdoctoral Researcher, DEVCOM Soldier Center

Abstract

Wearable thermal management technologies have attracted increasing attention due to their potential to provide localized heating and cooling for personal thermal comfort. Thermoelectric (TE) devices, or thermoelectric generators, offer the ability to provide this capability, but their application in wearable systems remains limited by mechanical flexibility, heat dissipation and temperature control.

This dissertation focuses on the development of flexible thermoelectric systems for wearable thermal management applications. First, flexible TE modules were designed and fabricated using Bi₂Te₃-based TE pillars, patterned copper electrodes and an Ecoflex insulating layer. Different electrode patterns and structural parameters were investigated to improve flexibility and device performance. The developed flexible TE modules showed multidirectional flexibility and good mechanical durability after repeated bending.

Second, flexible heatsinks were developed using AlN/Ecoflex composites, pin-fin structures, phase-change materials and copper foam to improve heat dissipation and extend cooling duration. The effect of black surface coating on cooling performance was also investigated. The combination of improved thermal conduction, increased surface area and thermal energy storage extended the effective cooling duration.

Finally, the flexible TE modules and heatsinks were integrated with a PID controller and a rechargeable lithium-ion battery to develop a wearable thermal management system with wireless communication and mobile app control. The integrated system was evaluated under different operating conditions, including environmental temperature, airflow, bending and operating strategies. The system demonstrated closed-loop temperature regulation in both heating and cooling modes, as well as switching between the two modes.

Overall, this research demonstrates the integration of flexible TE modules, thermal management materials and temperature control into a wearable system for localized heating and cooling.