Internal thermometer

• US 6,254,548 B1
• Filed: 11/24/1999
• Issued: 07/03/2001
• Est. Priority Date: 11/25/1998
• Status: Expired due to Fees

• Current Assignee: Ball Semiconductor, Inc.
• Original Assignee: Ball Semiconductor, Inc.
• Inventors: Ishikawa, Akira, Ahn, Samuel S., Ahn, Suzanne I., Takeda, Nabuo, Hays, Steven R., Gaffney, F. Andrew
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): WINGOOD, PAMELA LYNN
• Application Number:
  US09/448,638
• Time in Patent Office: 587 Days
• Field of Search: 600/549, 600/555, 600/486
• US Class Current: 600/549
• CPC Class Codes: A61B 5/0008 Temperature signals
• CPC Class Codes: A61B 5/0031 Implanted circuitry

Abstract

A miniature spherical-shaped internal temperature transponder. A temperature sensor (25) is fabricated in a spherical integrated transponder circuit (15) which may be placed in the human body by ingestion, implantation, or injection. In one aspect of the invention, a passive system is disclosed whereby an external monitoring station (13) generates an energy field using a magnetic field generator (19) which is coupled to a power coil (21) of the transponder (15). The power coil (21) passes power to a power regulator (23) to provide regulated power to all transponder (15) circuits. Temperature data obtained by the temperature sensor (25) is passed to a voltage controlled oscillator (27) for conversion into an RF signal. A mixing circuit (31) receives the RF temperature signal and modulates the temperature data signal onto an oscillator frequency from an RF oscillator (29). An RF amplifier (33) receives the modulated RF signal from the mixing circuit (31) and transmits it via an antenna (35) to the external monitor station 13 which is proximate to the transponder (15). The signal is received by an RF receiver (37) and processed using a CPU (39) to extract the measured temperature data, which can then be displayed to the operator on a display (41). The transponder (15) may be powered either by the external electromagnetic radiation source (19) or an internal battery.

Claims

1. A method of monitoring an internal temperature, which comprises the steps of:

placing an externally powered temperature transponder internally of a body wherein said transponder is formed on a single, substantially spherical semiconductor substrate;

generating electromagnetic radiation externally of the body to power the transponder;

generating an RF signal based upon the temperature of the transponder;

receiving the RF signal; and

determining the internal temperature based upon the received modulated RF signal.

2. The method of claim 1, wherein the transponder is approximately one millimeter in diameter.

3. The method of claim 1, wherein the transponder is small enough to be easily ingested.

4. The method of claim 3, wherein the transponder is large enough not to be absorbed through microvilli of a digestive tract.

5. An internal thermometer which comprises:

a semiconductor substrate;

a temperature sensor residing on said substrate;

means residing on said substrate for generating an RF signal corresponding to the temperature sensed by said temperature sensor;

means residing on said substrate for powering circuitry residing on said substrate in response to an external electromagnetic signal;

wherein

said temperature sensor includes means for producing a voltage corresponding to said temperature; and

,

said means for generating said RF signal corresponding to said temperature includes a voltage controlled oscillator residing on said substrate and coupled to said temperature sensor.

6. The internal thermometer of claim 5, wherein said means for generating said RF signal corresponding to said temperature sensed by said temperature sensor further comprises:

an RF oscillator residing on said substrate; and

,

a mixing circuit residing on said substrate, said mixing circuit being coupled to said RF oscillator and said voltage controlled oscillator.

7. The internal thermometer of claim 5, wherein said substrate is substantially spherical.

8. An internal thermometer, comprising:

a temperature sensor;

a circuit ball electrically coupled to said temperature sensor, said circuit ball comprising a substantially spherical substrate and circuitry residing on said substrate for generating an RF signal corresponding to the temperature sensed by said temperature sensor; and

,

means for powering said RF generating circuitry and said temperature sensor.

9. The internal thermometer of claim 8, wherein said temperature sensor resides on said spherical substrate of said circuit ball.

10. The internal thermometer of claim 8, wherein said temperature sensor is defined by a substantially spherical sensor ball electrically coupled to said circuit ball.

11. The internal thermometer of claim 8, wherein said means for powering said RF generating circuitry and said temperature sensor includes circuitry residing on said sensor ball for generating power in response to an external electromagnetic signal.