Magnetoelectric data and power to miniature biodevices with tunable amplitude and waveform
The disclosure describes new apparatus, systems and methods utilizing magnetoelectric neural stimulators with tunable amplitude and waveform. Specific embodiments of the present disclosure include a magnetoelectric film, a magnetic field generator and an electrical circuit coupled to the magnetoelectric film, in particular embodiments, the electrical circuit comprises components configured modify an electrical output signal produced by the magnetoelectric film. In certain embodiments, the electrical circuit is configured to modify the electric signal to charge a charge storage element, to transmit data to an implantable wireless neural stimulator, and to provide a stimulation output to electrodes.
1 . A system comprising:
a magnetoelectric film;
a magnetic field generator configured to generate a magnetic field at an input frequency between 20-500 kHz, wherein the magnetic field generator is configured to transmit downlink data by performing amplitude shift keying (ASK) modulation of the magnetic field; and
an electrical circuit coupled to the magnetoelectric film, wherein:
the magnetoelectric film is configured to produce an electrical output signal when the magnetoelectric film is stimulated by the magnetic field at the input frequency;
the electrical circuit configured to receive the electrical output signal comprises:
a charging circuit configured to extract power based on the electrical output signal;
a stimulation driver configured to modify the electrical output signal such that the electrical output signal has an output frequency between 0.5-1000 Hz to stimulate a biological tissue; and
a data circuit configured to recover the downlink data encoded via the amplitude shift keying (ASK) modulation of the magnetic field; and
the electrical circuit is configured to transition between the power, the stimulation and the data recovery based on modulation of the magnetic field.
2 . The system of claim 1 wherein:
the magnetoelectric film comprises a central portion; and
the electrical circuit is coupled to the central portion of the magnetoelectric film.
3 . The system of claim 1 wherein: the magnetoelectric film has a resonant frequency; and
the input frequency is within ten percent of the resonant frequency of the magnetoelectric film.
4 . The system of claim 1 wherein the magnetic field generator is configured to generate a series of pulses of the magnetic field.
5 . The system of claim 4 wherein each pulse in the series of pulses has a duration of approximately 1 millisecond (ms).
6 . The system of claim 4 wherein: the electrical output signal has an output voltage; and
an amplitude of the output voltage depends on a duration of pulses in the series of pulses.
7 . The system of claim 4 wherein: the electrical output signal has an output voltage; and
an amplitude of the output voltage depends on a total number of pulses in the series of pulses.
8 . The system of claim 1 wherein the electrical output signal is a monophasic or biphasic output signal.
9 . The system of claim 1 wherein the magnetoelectric film comprises a magnetostrictive layer and a piezoelectric layer; a polyvinylidene fluoride (PVDF) layer; or a lead zirconate titanate (PZT) layer.
10 . The system of claim 1 , further comprising an electronic device, wherein the electrical output signal powers the electronic device.
11 . The system of claim 1 wherein the magnetoelectric film is a first magnetoelectric film, wherein the apparatus further comprises a second magnetoelectric film, and wherein the electrical circuit is coupled to the second magnetoelectric film.
12 . The system of claim 1 wherein the magnetic field generator comprises an electromagnet.
13 . The system of claim 1 wherein the magnetic field generator further comprises a permanent magnet.
14 . The system of claim 1 wherein the electrical components comprise a full wave rectifier and a transistor.
15 . The system of claim 1 wherein the electrical components comprise a diode and a capacitor.
16 . The system of claim 1 wherein the apparatus further comprises a stereotrode and wherein the electrical output signal is transmitted through the stereotrode.
17 . The system of claim 1 wherein the magnetic field generator configured to generate the magnetic field at the input frequency within five percent of the resonant frequency of the magnetoelectric film.
18 . The system of claim 1 , wherein:
prior to transmitting the downlink data, the magnetic field generator is configured to transmit a pilot tone as an unmodulated portion of the magnetic field that is received by the electrical circuit via the magnetoelectric film; and
the electrical circuit is configured to extract a threshold voltage based on the pilot tone to decode the downlink data.
19 . A system comprising:
a magnetoelectric film;
a magnetic field generator configured to generate a magnetic field at an input frequency between 20-500 kHz, wherein the magnetoelectric film is configured to produce an electrical output signal with a voltage waveform when the magnetoelectric film is stimulated by the magnetic field at the input frequency; and
an electrical circuit or material coupled to the magnetoelectric film to modify the voltage waveform, wherein:
the magnetic field generator is configured to transmit downlink data to control at least part of the system by performing amplitude shift keying modulation of the magnetic field; and
the electrical circuit or material comprises electric components configured to:
modify the electrical output signal such that the electrical output signal has an output frequency between 0.5-1000 Hz; and
recover the downlink data encoded via the amplitude shift keying modulation of the magnetic field.