Ophthalmic devices and methods with application specific integrated circuits
View Patent ↗Ophthalmic devices with dynamic electro-active elements offer variable optical power and/or depth of field that restore lost accommodation in individuals suffering from presbyopia or aphakia. An illustrative device senses physiological processes indicative of the accommodative response and actuates a dynamic electro-active element to provide the desired change in optical power and/or depth of field. The illustrative device includes two application-specific integrated circuits (ASICs) for processing the accommodative response and actuating the electro-active element: a high-voltage ASIC that steps up a low voltage from a power supply to a higher voltage suitable for actuating the electro-active element, and another ASIC that operates at low voltage (and therefore consumes little power) and controls the operating state of the high-voltage ASIC. Because each ASIC operates at the lowest possible voltage, the illustrative ophthalmic device dissipates less power than other ophthalmic devices.
1. An implantable ophthalmic device comprising:
a high-voltage application-specific integrated circuit (ASIC) configured to actuate an electro-active element at a first voltage; and
a low-voltage ASIC operably coupled to the high-voltage ASIC and configured to (i) regulate the high-voltage ASIC and (ii) operate at a second voltage lower than the first voltage.
2. The implantable ophthalmic device of claim 1 wherein the low-voltage ASIC is configured to regulate the high-voltage ASIC by causing the high-voltage ASIC to transition from an idle state to an operational state.
3. The implantable ophthalmic device of claim 1 wherein the second voltage is about 5 volts or less and the first voltage is about 5 volts to about 11 volts.
4. The implantable ophthalmic device of claim 1 further comprising:
a power supply configured to supply current to at least one of the high-voltage and low-voltage ASICs at a power supply voltage equal to or less than the second voltage.
5. The implantable ophthalmic device of claim 4 wherein the high-voltage ASIC includes a charge pump to transform the power supply voltage to the first voltage.
6. The implantable ophthalmic device of claim 4 further comprising:
a switch configured to enable current flow from the power supply to the high-voltage ASIC in response to a signal from the low-voltage ASIC; and
a power-on reset block configured to reset the high-voltage ASIC in response to actuation of the switch.
7. The implantable ophthalmic device of claim 4 wherein the power supply includes a battery and further comprising a battery charger operably coupled to the battery and configured to charge the battery.
8. The implantable ophthalmic device of claim 7 further comprising:
a radio-frequency (rf) antenna operably coupled to the battery charging and configured to couple rf energy to the battery charger;
a resonating capacitor in series with the rf antenna to provide an impedance for altering power transfer characteristics of the rf antenna; and
a tuner to trim the resonating capacitor.
9. The implantable ophthalmic device of claim 7 wherein the battery charger is configured to charge the battery by:
(i) charging the battery at a constant current until the battery reaches a predetermined voltage; and
(ii) charging the battery at a constant voltage for a predetermined time after the battery reaches the predetermined voltage.
10. The implantable ophthalmic device of claim 9 wherein the constant current is about 120 μA to about 180 μA.
11. The implantable ophthalmic device of claim 9 wherein the predetermined voltage is about 1.6 V to about 1.8 V.
12. The implantable ophthalmic device of claim 4 wherein the power supply includes a solar cell.
13. The implantable ophthalmic device of claim 1 wherein at least one of the high-voltage and low-voltage ASICs includes a nonvolatile memory configured to store information for actuating the electro-active element.
14. The implantable ophthalmic device of claim 1 wherein at least one of the high-voltage and low-voltage ASICs includes a programmable logic controller to determine an actuation state of the electro-active element based on an accommodation signal representative of an accommodative response of a patient's eye.
15. The implantable ophthalmic device of claim 14 wherein at least one of the high-voltage and low-voltage ASICs includes an analog-to-digital converter (ADC) configured to convert an analog signal from a sensor into the accommodation signal.
16. The implantable ophthalmic device of claim 15 wherein at least one of the high-voltage and low-voltage ASICs further includes a bandgap block configured to provide a reference voltage that is independent of both temperature and a power supply voltage to the ADC.
17. The implantable ophthalmic device of claim 1 wherein at least one of the high-voltage and low-voltage ASICs has a length of about 2 mm or less or and a width of about 2 mm or less.
18. The implantable ophthalmic device of claim 1 wherein the high-voltage and low-voltage ASICs are hermetically sealed.
19. An implantable ophthalmic device comprising:
a power supply configured to supply current at a first voltage to a low-voltage application-specific integrated circuit (ASIC) and a high-voltage ASIC;
a charge pump operably coupled to the power supply and configured to transform the first voltage to a second voltage that is greater than the first voltage and suitable for actuating an electro-active element; and
a battery charger operably coupled to the battery and configured to charge the battery:
(i) at a constant current until the battery reaches a predetermined voltage; and
(ii) at a constant voltage for a predetermined time after the battery reaches the predetermined voltage.