Apparatus for performing multiple different measurements on a small specimen sample, enabling testing and diagnoses in real time at the point of care are described. The core of the apparatus includes an ultrasonic resonator cavity where acoustic resonances are used to determine the speed of sound and sound attenuation in a single droplet. Acoustic measurements are made in the reflection mode using electrical impedance of a small piezoelectric crystal transducer that operates in the thickness longitudinal mode. Combination of this technology with electromagnetic, electrical, and magnetic fields permits multiple types of measurements to be made using the same resonator cavity.