Highly stretchable self-sensing actuator based on conductive photothermally-responsive hydrogel

Chiao Yueh Lo, Yusen Zhao, Cheolgyu Kim, Yousif Alsaid, Roozbeh Khodambashi, Matthew Peet, Rebecca Fisher, Hamid Marvi, Spring Berman, Daniel Aukes, Ximin He

Research output: Contribution to journalArticlepeer-review

95 Scopus citations


Soft robots built with active soft materials have been increasingly attractive. Despite tremendous efforts in soft sensors and actuators, it remains extremely challenging to construct intelligent soft materials that simultaneously actuate and sense their own motions, resembling living organisms’ neuromuscular behaviors. This work presents a soft robotic strategy that couples actuation and strain-sensing into a single homogeneous material, composed of an interpenetrating double-network of a nanostructured thermo-responsive hydrogel poly(N-isopropylacrylamide) (PNIPAAm) and a light-absorbing, electrically conductive polymer polypyrrole (PPy). This design grants the material both photo/thermal-responsiveness and piezoresistive-responsiveness, enabling remotely-triggered actuation and local strain-sensing. This self-sensing actuating soft material demonstrated ultra-high stretchability (210%) and large volume shrinkage (70%) rapidly upon irradiation or heating (13%/°C, 6-time faster than conventional PNIPAAm). The significant deswelling of the hydrogel network induces densification of percolation in the PPy network, leading to a drastic conductivity change upon locomotion with a gauge factor of 1.0. The material demonstrated a variety of precise and remotely-driven photo-responsive locomotion such as signal-tracking, bending, weightlifting, object grasping and transporting, while simultaneously monitoring these motions itself via real-time resistance change. The multifunctional sensory actuatable materials may lead to the next-generation soft robots of higher levels of autonomy and complexity with self-diagnostic feedback control.

Original languageEnglish (US)
Pages (from-to)35-43
Number of pages9
JournalMaterials Today
StatePublished - Nov 2021


  • Conducting polymer
  • LCST
  • Photothermal responsive hydrogel
  • Self-monitoring
  • Soft actuator
  • Soft robotics
  • Strain sensor

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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