alt and pH sensing: Etalons were fabricated based on previous procedure (Figure S12). For the salt response investigation, the swimming device was put into deionized water with the etalons fully immersed under water overnight. Pictures were taken to record the initial color. Then the media was then changed to 0.5 M NaCl solution, and pictures taken every minute to record the color change. Similarly, for pH sensing, pH 6.02 was used to record initial color. Then the media was adjusted to pH 2.69 and then 10.99.  Color evolution was recorded by the camera system.

Acknowledgements

Michael J. Serpe acknowledges funding from the University of Alberta (the Department of Chemistry and the Faculty of Science), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Foundation for Innovation (CFI), and the Alberta Advanced Education & Technology Small Equipment Grants Program (AET/SEGP). Yu Wan acknowledges Alberta Innovates Technology Futures for a Graduate Student Scholarship.

Conflict of interest

All authors declare no financial/commercial conflicts of interest.