WIRELESS VOLTAGE SENSING DEVICE

• US 20130207639A1
• Filed: 02/11/2013
• Published: 08/15/2013
• Est. Priority Date: 02/10/2012
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Rajagopal, Aditya, Scherer, Axel, Chang, Chieh-Feng, Sadek, Akram Sarwat, Jimenez, Raymond
• Granted Patent: US 9,128,124 B2
• Time in Patent Office: Days
• US Class Current: 324/97
• CPC Class Codes: A61B 2560/0214 of power generation or supply
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 2562/166 the sensor is mounted on a specially adapted printed circuit board
• CPC Class Codes: A61B 2562/223 Optical cables therefor
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof

Abstract

A voltage sensing apparatus on a semiconductor substrate, including one or more inputs comprising metal contacts, an output comprising a laser transmitter, circuitry electrically connecting and interfacing the inputs to the output; and a power module. A method of fabricating the apparatus is also described.

Claims

1. A voltage sensing apparatus, comprising:

a semiconductor substrate;

one or more inputs, comprising metal contacts, on the substrate;

an output, comprising a laser transmitter, on the substrate;

circuitry, on the substrate, electrically connecting and interfacing the inputs to the output; and

a power module on the substrate and electrically connected to the circuitry.

2. The apparatus of claim 1, wherein:

the metal contacts are on one or more probe areas defined on the substrate, and

the circuitry, the probe areas, the power module, and the laser transmitter are within a surface area of the substrate of 4000 micrometers by 1000 micrometers or less and within a height of 200 micrometers or less.

3. The apparatus of claim 2, wherein:

(i) the metal contacts produce one or more voltage waveforms in response to one or more stimuli external to the substrate,

(ii) the circuitry converts the voltage waveforms into one or more signals,

(iii) the circuitry modulates the laser transmitter'"'"'s output with the signals, and

(iv) the laser transmitter'"'"'s output comprises electromagnetic radiation that transmits the signals off the semiconductor substrate and the apparatus.

4. The apparatus of claim 2, wherein the circuitry comprises:

(i) voltage to current converter circuit that converts one or more voltage waveforms into one or more current waveforms, the voltage waveforms produced by the metal contacts in response to one or more stimuli external to the substrate,

(ii) a modulator circuit that modulates the current waveforms to form one or more modulated waveforms;

(iii) a mixer circuit that heterodynes the modulated waveforms to form one or more heterodyned waveforms; and

(iv) a laser circuit that drives and modulates the laser transmitter with the heterodyned waveform, wherein the laser transmitter outputs electromagnetic radiation that transmits the heterodyned waveforms, representing the voltage waveforms, off the apparatus and the semiconductor substrate.

5. The apparatus of claim 4, wherein:

the modulator circuit includes a differential voltage controlled oscillator (VCO) and the current waveforms modulate the VCO'"'"'s center frequency to form one or more VCO waveforms; and

the mixer circuit heterodynes the VCO waveforms to form the heterodyned waveforms.

6. The apparatus of claim 4, wherein the modulator circuit includes a differential voltage controlled oscillator having instability (no direct current equilibrium).

7. The apparatus of claim 4, further comprising:

a photodetector;

a demodulator circuit connected to the photodetector, wherein the demodulator circuit demodulates the one or more signals and restores the voltage waveforms, when the photodetector is optically coupled to the laser transmitter.

8. The apparatus of claim 2, wherein:

the probe areas have a length of 2000 micrometers or less, a width of 50 micrometers or less, and a triangular first end having a height of 5 micrometers or less;

the probe areas are separated by 200 micrometers or less;

the metal contacts are disposed in a diamond formation, comprise platinum, and have an area of 20 micrometers by 20 micrometers or less; and

the circuitry has a length and width of 500 micrometers or less.

9. The apparatus of claim 1, wherein:

the metal contacts have an input impedance of more than 1 MegaOhm;

the power module provides more than 1.4 milliwatts of input electrical power;

the circuitry consumes 400 microwatts of power or less and has voltage rails of +/−

2V or less; and

the laser transmitter emits modulated electromagnetic radiation having a transmission frequency of 20 Megahertz or less.

10. The apparatus of claim 1, wherein the circuitry and laser operate with a combined power of less than 400 microwatts, provided by the power module.

11. The apparatus of claim 10, wherein the power module is a battery.

12. The apparatus of claim 1, wherein the power module is a photovoltaic device.

13. The apparatus of claim 12, further comprising:

an optical fiber connected to the photovoltaic device; and

a length of the optical fiber that extends to free space or to a light source when the substrate is implanted in an object, so that the photovoltaic device receives optical power along the optical fiber.

14. The apparatus of claim 1, further comprising:

an optical fiber connected to the laser; and

a length of the optical fiber that extends to free space when the substrate is implanted in an object, so that the laser transmitter transmits the electromagnetic radiation to free space along the optical fiber.

15. The apparatus of claim 1, wherein the apparatus is biocompatible and bioimplantable on or inside a human tissue or a human being.

16. The apparatus of claim 1, wherein the laser emits near infrared light, or light that is transmitted through a transmission window of human tissue.

17. The apparatus of claim 1, wherein the metal contacts are platinum.

18. The apparatus of claim 1, wherein the apparatus is an integrated circuit chip.

19. A method of fabricating a voltage sensing device, comprising:

providing one or more probe areas defined onto a semiconductor substrate;

providing one or more metal contacts on the probe areas, wherein the metal contacts produce voltage waveforms in response to one or more stimuli external to the substrate;

providing circuitry on the semiconductor substrate, wherein the circuitry includes;

(i) a voltage to current converter circuit on the substrate and electrically connected to the metal contacts, wherein the voltage to current converter circuit converts the voltage waveforms into current waveforms,

(ii) a modulator circuit on the substrate and electrically connected to the voltage to current converter circuit, wherein the modulator circuit modulates the current waveforms to form modulated waveforms;

providing a laser transmitter and laser circuit on the semiconductor substrate, electrically connected to the modulator circuit, wherein the laser transmitter transmits the modulated waveform off the substrate; and

providing a power module on the semiconductor substrate and in electrical connection with the circuitry, wherein the power module provides power to the laser transmitter and the circuitry.

20. The method of claim 19, further comprising:

lithographically defining and etching the one or more probe areas on the semiconductor substrate;

depositing a thermal oxide on both sides of the substrate;

depositing a stiction layer on the probe areas;

defining and depositing the one or more metal contacts or pads on the stiction layer;

depositing metallization to electrically connect the metal contacts to the circuitry;

depositing metallization to electrically connect the circuitry to the laser transmitter; and

depositing metallization to electrically connect the power module to the circuitry.