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 (P) 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 (P) 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 (P) 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 . <EOS>