Background,Motivation and Objective The medical imaging field continues to require an imaging modality with tissue conductivity contrast.Tumor angiogenesis and necrotic cores create conductivity contrasts,and in the RF frequency range cell membrane structure strongly influences tissue impedance and absorption rates,illustrating medical applications of mapping dielectric properties of tissue.Furthermore,portability and ease of use considerations push imaging systems towards full non-contact operation.We propose a non-contact radio frequency(RF)/ultrasound hybrid imaging system based on the local RF energy absorption and the thermoacoustic(TA) effect.Airborne capacitive micromachined ultrasonic transducers(CMUTs) are used to create images by standoff detection of the thermoacoustic-generated pressure waves that originate from deep within tissue and propagate through the air interface.