**6. Conclusions**

Whether constructed covalently from monomers or not, whether aqueous soluble or not, whether cross-linked or not, or whether solid or not, polymers offer unique environments and objects as playgrounds for sensors and logic designers. These efforts lead to reusable sensors, insights into the spatial distribution of chemical species near interfaces, membrane-assembled logic systems, temperature maps within living cells, and identification protocols for submillimetric objects.

**Author Contributions:** Conceptualization, A.P.d.S.; writing—original draft preparation, C.-Y.Y., S.U., A.P.d.S.; writing—review and editing, C.-Y.Y., S.U., A.P.d.S.; funding acquisition, S.U.

**Funding:** This work was funded by China Scholarship Council and Japan Society for the Promotion of Science (Grant-in-Aid for Scientific Research (B) (17H03075)).

**Acknowledgments:** We thank Jean-Philippe Soumillion (Universite Louvain-la-Neuve, for collaboration on **7**), Otto Wolfbeis (Universitat Regensburg, for collaboration on **8**), Jim Tusa (Optimedical Inc, for collaboration on **9**), Mark James and Dave Pears (Avecia, for collaboration on **10**–**12**), Kaoru Iwai (Nara Women's University, for collaboration on **13**, **15**, **16**, **20** and **21**), Seiji Tobita and Toshitada Yoshihara (Gunma University, for collaboration on **14** and **17**), Kohki Okabe and Takashi Funatsu (The University of Tokyo, for collaboration on **22** and **23**), Yoshie Harada (Osaka University, for collaboration on **22** and **23**), Noriko Inada (Osaka Prefecture University, for collaboration on **23**) and Satoshi Yoshida and Aruto Yoshida (KIRIN Company Limited, for collaboration on **24** and **25**).

**Conflicts of Interest:** The authors declare no conflict of interest.
