Visualization and Quantification of Microwaves Using Thermoresponsive Color-Change Hydrogel

Minami Nakamitsu, Hiroaki Imai, Yuya Oaki

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Visualization and quantification of invisible lights, such as microwaves, are significant for their safe use. In general, a sensitizer material combined with a transistor is used as electronic devices for the measurement. Here, we developed a thermoresponsive color-change hydrogel of poly(N-isopropylacrylamide) (PNIPAAm) cross-linked by a layered organic composite based on polydiacetylene (PDA) for visualization and colorimetric quantification of microwaves. The layered PDA in the PNIPAAm hydrogel showed the temperature-dependent gradual color change with heating. Irradiation of microwaves induced the color change of PDA through heating of water in the hydrogel and subsequent volume shrinkage. The color of the gel was applied to visualize the temperature distribution with increasing irradiation time of microwaves. Moreover, the power of the irradiated microwave was quantified by time to the complete color change of the gel. The results indicate that the stimulus conversion process has potentials for development of a variety of imaging and quantification devices based on the layered PDA.

Original languageEnglish
Pages (from-to)133-139
Number of pages7
JournalACS Sensors
Issue number1
Publication statusPublished - 2020 Jan 24


  • colorimetric sensors
  • external stimuli
  • hydrogel
  • layered materials
  • microwave
  • polydiacetylene
  • stimuli conversion
  • stimuli-responsive material

ASJC Scopus subject areas

  • Bioengineering
  • Instrumentation
  • Process Chemistry and Technology
  • Fluid Flow and Transfer Processes


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