An implantable medical electrical stimulation device, comprising: an electrical stimulation therapy circuit operably coupled to one or more electrodes configured to deliver electrical stimulation therapy; a rechargeable battery configured to power the electrical stimulation therapy circuit; and an array of piezoelectric transducers, wherein each of the piezoelectric transducers includes a receiving face configured to receive transmitted ultrasonic waves in a frequency range of between about 100 kHz and about 5 MHz, the ultrasonic waves being convertible to a source of electrical energy for a selective recharging of the rechargeable battery; and characterized in that the medical electrical stimulation device further comprises: a feedback coil configured to generate an indication level of regenerative electrical power received from transmitted ultrasonic waves; wherein the array of piezoelectric transducers includes at least one transducer having a receiving face oriented at an oblique angle with respect to a poling axis of the transducer, wherein the receiving faces of the array of piezoelectric transducers are covered in a domed epoxy layer and biocompatible titanium casing layer configured to focus transmitted ultrasonic waves towards the receiving faces of the array of piezoelectric transducers, and wherein the array of piezoelectric transducers is configured to receive transmitted ultrasonic waves across a range of about 40 degrees relative to a central poling axis of the array of the piezoelectric transducers. a rechargeable battery configured to power the electrical stimulation therapy circuit; and an array of piezoelectric transducers, wherein each of the piezoelectric transducers includes a receiving face configured to receive transmitted ultrasonic waves in a frequency range of between about 100 kHz and about 5 MHz, the ultrasonic waves being convertible to a source of electrical energy for a selective recharging of the rechargeable battery; and characterized in that the medical electrical stimulation device further comprises: a feedback coil configured to generate an indication level of regenerative electrical power received from transmitted ultrasonic waves; wherein the array of piezoelectric transducers includes at least one transducer having a receiving face oriented at an oblique angle with respect to a poling axis of the transducer, wherein the receiving faces of the array of piezoelectric transducers are covered in a domed epoxy layer and biocompatible titanium casing layer configured to focus transmitted ultrasonic waves towards the receiving faces of the array of piezoelectric transducers, and wherein the array of piezoelectric transducers is configured to receive transmitted ultrasonic waves across a range of about 40 degrees relative to a central poling axis of the array of the piezoelectric transducers. a feedback coil configured to generate an indication level of regenerative electrical power received from transmitted ultrasonic waves; wherein the array of piezoelectric transducers includes at least one transducer having a receiving face oriented at an oblique angle with respect to a poling axis of the transducer, wherein the receiving faces of the array of piezoelectric transducers are covered in a domed epoxy layer and biocompatible titanium casing layer configured to focus transmitted ultrasonic waves towards the receiving faces of the array of piezoelectric transducers, and wherein the array of piezoelectric transducers is configured to receive transmitted ultrasonic waves across a range of about 40 degrees relative to a central poling axis of the array of the piezoelectric transducers.