Pressure sensors for small-scale applications and related methods
Certain pressure sensor devices are much smaller than prior art devices, yet are at least as sensitive as the prior art devices. A capacitive pressure sensor can include a flexible substrate that permits bending of a pressure sensing region without significantly affecting operation thereof. The pressure sensor can include a flexible membrane in which an electrode is sandwiched between two layers of polymeric material. The sandwiched electrode can be extremely close to a reference electrode so as to provide for highly sensitive capacitance readings, yet the membrane can be restricted from contacting the reference electrode under high pressure conditions.
1. A system for monitoring fluid pressure within an eye, the system comprising:
a substrate;
a pressure sensor coupled with the substrate;
an integrated circuit coupled with the substrate and electrically coupled with the pressure sensor;
an antenna coupled with the substrate and electrically coupled with the integrated circuit, the antenna and integrated circuit adapted to receive a first wireless signal for powering the system and transmit a second wireless signal, the second wireless signal providing an indication of the fluid pressure; and
an LED coupled with the substrate and electrically coupled with the integrated circuit, wherein a maximum width of the LED is not greater than the maximum width of the substrate, wherein the light intensity of the LED output provides an indication of power being received by the system from a wireless external power source.
2. The system of claim 1 , wherein the antenna transmits the second signal at a harmonic of the frequency of the first signal.
3. The system of claim 1 , wherein the harmonic is the third harmonic of the first signal.
4. The system of claim 1 , wherein the substrate defines a maximum width of no greater than about 0.7 millimeters;
wherein a maximum width of the pressure sensor is no greater than the maximum width of the substrate; and
wherein a maximum width of the integrated circuit is no greater than the maximum width of the substrate.
5. The system of claim 1 wherein the pressure sensor is placed in a non-human.
6. The system of claim 5 , wherein the pressure sensor is implanted in the eye of the non-human.
7. The system of claim 1 , wherein the substrate is polymeric.
8. The system of claim 1 , wherein the sensitivity is substantially constant over a range of from about 0 mmHg to about 50 mmHg above atmospheric pressure.
9. The system of claim 8 , wherein the pressure sensor has a sensitivity of no less than about 0.3 fF/mmHg.
10. The system of claim 1 , wherein the substrate is flexible so as to be able to conform to a curved surface.
11. The system of claim 10 , wherein the pressure sensor has a flat orientation and a curved orientation, and in which the pressure sensor has a sensitivity of no less than about 0.3 fF/mmHg whether the substrate is in a flat orientation or a curved orientation.
12. The system of claim 11 , wherein the sensitivity is substantially constant over a range of from about 0 mmHg to about 50 mmHg above atmospheric pressure.
13. The system of claim 1 , wherein the membrane has a depth of no greater than about 7 microns when the membrane is in an uncompressed position.
14. The system of claim 1 , wherein a perimeter of the substrate defines an area of no greater than about 2 millimeters 2 .
15. The system of claim 14 , wherein the membrane has a depth of no greater than about 7 microns when the membrane is in an uncompressed position.
16. The system of claim 15 , wherein the substrate defines a maximum width of no greater than about 0.7 millimeters;
wherein a maximum width of the pressure sensor is no greater than the maximum width of the substrate; and
wherein a maximum width of the integrated circuit is no greater than the maximum width of the substrate.
17. The system of claim 16 , wherein the substrate is polymeric.