Miniaturized Broadband Microwave Permittivity Sensing for Biomedical Applications

We present a compact, scalable, and broadband architecture for the implementation of complex microwave permittivity sensors in complementary metal-oxide semiconductor (CMOS) technology. The proposed architecture consists of a patch sensor embedded in a programmable balanced readout bridge and performs third and fifth harmonic downconversion for fast multi-frequency readout. Circuits designed can act as the basic building block for a wide span of biomedical applications, ranging from wearables to permittivity imaging. Experimental results of manufactured prototypes demonstrate measurement noise reduction through bridge balancing, Debye model parameter estimation of independent material with a 1.6% error using full frequency dataset, and 5.3% in high energy efficiency mode, as well as image construction based on material permittivity differences.