SCIENCE CHINA Materials, Volume 61, Issue 7: 969-976(2018) https://doi.org/10.1007/s40843-018-9266-8

A skin-like stretchable colorimetric temperature sensor

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  • ReceivedJan 11, 2018
  • AcceptedMar 28, 2018
  • PublishedApr 16, 2018


Wearable and stretchable physical sensors that can conformally contact on the surface of organs or skin provide a new opportunity for human-activity monitoring and personal healthcare. Particularly, various attempts have been made in exploiting wearable and conformal sensors for thermal characterization of human skin. In this respect, skin-mounted thermochromic films show great capabilities in body temperature sensing. Thermochromic temperature sensors are attractive because of their easy signal analysis and optical recording, such as color transition and fluorescence emission change upon thermal stimuli. Here, desirable mechanical properties that match epidermis are obtained by physical crosslinking of polydiacetylene (PDA) and transparent elastomeric polydimethylsiloxane (PDMS) networks. The resulting PDA film displayed thermochromic and thermo- fluorescent transition temperature in the range of 25–85°C, with stretchability up to 300% and a skin-like Young’s modulus of ~230 kPa. This easy signal-handling provides excellent references for further design of convenient noninvasive sensing systems.

Funded by

the National Key Research and Development Program of China(2016YFB0700300)

the National Natural Science Foundation of China(51503014,51501008)

and the State Key Laboratory for Advanced Metals and Materials(2016Z-03)


This work was supported by the National Key Research and Development Program of China (2016YFB0700300), the National Natural Science Foundation of China (51503014 and 51501008), and the State Key Laboratory for Advanced Metals and Materials (2016Z-03).

Interest statement

The authors declare no conflict of interest.

Contributions statement

Chen Y designed and engineered the samples; Xi Y performed the experiments with support from Ke Y; Chen Y wrote the paper. All authors contributed to the general discussion.

Author information

Yingzhi Chen is a Lecturer of the School of Materials Science and Engineering, University of Science and Technology Beijing, China. Her research mainly focuses on the design, fabrication of optoelectronic compounds & devices, as well as novel biomedical materials.

Lu-Ning Wang is a Thousand Youth Talent, Professor and Dean of the School of Materials Science and Engineering, University of Science and Technology Beijing, China. His research mainly focuses on the design, preparation, theoretical study of novel biomedical materials. He has published more than 20 peer reviewed papers, and is an editorial board member of International Journal of Nanomedicine.

Xiaohong Zhang is a Chang Jiang Scholar, Professor and Vice President of Soochow University. His research interests include organic optoelectronic materials, semiconductor nanomaterials, and optoelectronic devices. He has published more than 200 peer reviewed papers and applied more than 40 patents.


Supplementary information

Additional characterizations are available in the online version of the paper.


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  • Figure 1

    Schematic illustration of the design of the stretchable thermochromic temperature sensor.

  • Figure 2

    Photographs of pure PDMS film (a) and the polymerized PDA films at a heating temperature of 25, 40, 45, 50, 55, 60, and 70°C (b–h), denoted as PDA-25, PDA-40, PDA-45, PDA-50, PDA-55, PDA-60, and PDA-70, respectively according to the heating temperature.

  • Figure 3

    Plots of the maximum blue absorption shift Δλ652 (a), the colorimetric responses %CR (b), and the integral luminous transmittance Tlum(400–800 nm) (c) as a function of temperature.

  • Figure 4

    (a) Raman spectra of the as-prepared films; (b) magnified window of the green-dotted box in (a), showing PDMS (1414 cm−1) and PDA (1451 cm−1) fingerprints, which are used to calculate the temperature-dependent intensity ratio; (c) plots of Raman intensity1451/intensity1414 as a function of temperature; (d) proposed mechanism for the blue-to-red color transition. The applied heat induces the twist of backbone chain as well as single bond conformational change of a long alkyl side chain.

  • Figure 5

    (a) Schematic representation of the physical crosslinking of PDMS and PDA; (b) tensile stress–strain curves of the as-prepared thin films; (c) plots of tensile strength and ultimate strain as a function of temperature; (d) tensile strength versus Young’s modulus. Materials include the film prepared in this work (PDA film), polyvinyl alcohol gel (PVA gel) [41], double network gel (DN gel) [42], poly(N-acryloyl glycinamide) gel (PNAGA gel) [43], polyurethane (PEU gel) [44], polypyrrole-grafted chitosan gel (DCh-Ppy gel) [45], nanocomposite hydrogels (NC gel) [46], hydrophobic association hydrogels (HA gel) [47], bacterial cellulose gel (BC gel) [48] and skin [4951].

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