Hydrogels with Tethered Transcription Circuit Elements for Chemical Communication and Collective Computation

Tissues, robots, and other distributed systems must communicate to make decisions about information originating from different physical locations and then orchestrate the responses. In tissues, for example, cell-cell communication is essential for morphogenesis, immune response, and wound healing. However, devising methods for programming distributed communication in synthetic materials to program behaviors such as multiscale pattern formation, motion, and self-assembly remains a challenge. Here, we devise a design principle for reliable distributed chemical computation and communication and then construct a library of transcription circuit elements, termed tethered genelets (TGs), that implement this design principle within networks of 50 μm hydrogel nodes (HNs). TGs exhibit digital behavior in the form of a "distance-response curve"─they switch off in response to signals emanating from HNs within a specific distance, but are unaffected by faraway signals. In experiments, we verify that TGs send and receive signals as designed and validate the function and modularity of a library of 15 TG circuit elements. The principle of "digital distance-response" and the library of circuit elements we construct together will allow a diverse range of distributed chemical behaviors, communication, and dynamics to be programmed into materials such as soft robots and responsive surfaces.