One illustrative integrated electromagnetic-acoustic sensor includes: a ground plane; a patch antenna above the ground plane to send or receive an electromagnetic (EM) signal having an EM signal frequency; and an array of capacitive micromachined acoustic transducers formed by cavities between the patch antenna and a base electrode to send or receive an acoustic signal having an acoustic signal frequency. One illustrative sensing method includes: driving or sensing a EM signal between a ground plane and a patch antenna; and driving or sensing an acoustic signal between the patch antenna and a base electrode, the base electrode and the patch antenna having an array of capacitive micromachined acoustic transducer cavities therebetween.