A continuous, non-invasive fetal heart rate measurement is produced using
one or more ultrasonic transducer array patches that are adhered or
attached to the mother. Each ultrasound transducer array is operated in
an autonomous mode by a digital signal processor to obtain data from
which fetal heart rate information can be derived. Each ultrasonic
transducer array patch comprises a multiplicity of subelements that are
switchably reconfigurable to form elements having different shapes, e.g.,
annular rings. Each subelement comprises a plurality of interconnected
cMUT cells that are not switchably disconnectable. The use of cMUT
patches will provide the ability to interrogate a three-dimensional space
electronically (i.e. without mechanical beam steering) with ultrasound,
using a transducer device that is thin and lightweight enough to stick to
the patient's skin like an EKG electrode. The ultrasound device can track
the fetal heart in three-dimensional space as it moves due to the
mother's motion or the motion of the unborn child within the womb.