Figure 4.

Subcutaneous insertion procedure for the hydrogel sensors. (A) Rats were permanently housed in sex-segregated cages with ample space for enrichment and exercise. Exercise wheels were later installed as they became available (B) Rats were lightly anesthetized with isoflurane gas; the implant areas were shaved and cleaned with an alcohol scrub before subcutaneous sensor insertion via an 18 gauge needle. (C) Rats were individually held to ensure warmth and comfort as they awakened after surgery. (D) Rats were temporarily housed in an observation cage before transfer back to their living space.