The objective of the proposed research is to present two novel electromagnetic devices. The first one is a photonics topological insulator for wavefront control SPDT switch. The second one is the biodegradable microwave sensor design for postsurgical monitoring. For the microwave waveguide switch, we present a sub-element rotation-based symmetry-breaking mechanism for a quantum valley Hall photonic topological insulator (PTI) with a bandgap of 15.8–19.0 GHz. The topological phase is switched between the K and K' points in a hexagonal lattice space by selectively rotating only the ring element within the patch-loaded hexapod unit cell, without requiring active electronic components or external magnetic field bias. For the biodegradable sensor work, we present the design, simulation, fabrication, and measurement results of a biodegradable sensor for postoperative monitoring. First, a split-ring resonator (SRR) with loaded interdigit capacitors is designed to resolve the sensing film thickness of 6.2 µm. Electromagnetic waves impinged on the sensor and the information is encoded in the back-reflected frequency spectrum. Additionally, to locate the sensor in the in-vivo environment, a 2-tag configurable is proposed. Lastly, we conducted both wired and wireless measurements in a controlled environment. The measured data show great alignment with the simulated results. Utilizing the same back-reflecting concept, we measured the response for a stent sensor that is designed for detecting the functionality of the stent. Both in-air measurement and flow machine measurements are shown.