Surgery – Diagnostic testing – Temperature detection
Reexamination Certificate
1999-11-24
2001-07-03
O'Connor, Cary (Department: 3736)
Surgery
Diagnostic testing
Temperature detection
C600S486000
Reexamination Certificate
active
06254548
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention is related generally to the field of clinical temperature monitoring, and more particularly to a method of and system for monitoring temperature with an ingestible or implantable, almost microscopic, temperature transponder, preferably built on a single semiconductor substrate.
BACKGROUND OF THE INVENTION
Typically, a patient's temperature is taken orally, axillary, or rectally. The method chosen is based upon the age and consciousness of the patient. Originally, temperature was measured with a conventional glass and mercury clinical thermometer. Glass and mercury thermometers can be dangerous to use and they require substantial time to reach the patient's actual temperature.
Recently, electronic or digital thermometers have been developed to overcome the shortcomings of conventional glass and mercury clinical thermometers. One type of digital thermometer is a tympanic thermometer, which senses infrared radiation from a patient's ear drum. Tympanic thermometers provide a fast temperature reading, but their accuracy tends not to be as good as conventional clinical thermometers. Another type of digital thermometer includes a temperature sensing probe and circuitry for calculating and displaying the temperature detected by the probe. The probe may be used in the same way as a conventional glass and mercury clinical thermometer to measure oral, axillary, or rectal temperature. The probe type digital thermometers tend to provide accurate temperature readings almost as fast as tympanic thermometers.
Existing clinical thermometers, whether conventional or digital, have certain drawbacks in terms of time and effort on the part of the healthcare professional and inconvenience to the patient. NASA (National Aeronautics and Space Administration) has developed an ingestible thermometer that it uses to monitor the temperature of its astronauts. The NASA thermometer includes a temperature sensor, a transmitter, and a battery encapsulated in a relatively large pill-like structure. The NASA ingestible thermometer transmits the astronaut's temperature periodically to an external receiver. The NASA ingestible thermometer offers certain advantages over conventional thermometers. Temperature is recorded substantially automatically and continuously without inconvenience to monitoring personnel or the subject. However, the NASA ingestible thermometer requires an internal battery, and therefore, is rather large and difficult to swallow, and consequently, nearly impossible for use with children. Moreover, the NASA ingestible thermometer is too expensive to be used in a doctor's office or hospital.
SUMMARY OF THE INVENTION
The present invention disclosed and claimed herein, in one aspect thereof, comprises a method and system for monitoring an internal temperature. According to this aspect, an almost microscopic temperature transponder is placed internally of a body. The transponder may be placed by ingestion, implantation, or injection. The transponder generates an RF signal based upon the temperature of the transponder. The RF signal is received externally of the body and the internal temperature is determined based upon the received RF signal. The transponder is powered either by an external electromagnetic radiation source or an internal battery.
In one aspect, the transponder of the present invention is built on a single semiconductor substrate. Preferably, the semiconductor substrate is substantially spherical in shape. A temperature sensor resides on the substrate. Signal generating circuitry residing on the substrate generates an RF signal corresponding to the temperature sensed by the temperature sensor. Power generating circuitry residing on the substrate powers the temperature sensor and the signal generating circuitry in response to the external electromagnetic signal. The temperature sensor produces a voltage that corresponds to temperature. The temperature sensor can include a thermistor. The temperature sensor is coupled to a voltage controlled oscillator. The voltage controlled oscillator produces a signal, the frequency of which is related to the temperature sensed by the sensor. The signal produced by the voltage controlled oscillator modulates an RF signal generated by RF oscillator circuitry residing on the substrate.
In another aspect, the transponder is built on a cluster of ball elements. The circuitry for generating a temperature dependent RF signal resides on a first substantially spherical semiconductor substrate. The temperature sensor resides on a second substantially spherical substrate coupled to the first substrate. The transponder may by powered either by a substantially spherical battery ball coupled to at least one of the first or second substrates, or by circuitry for generating power in response to an external electromagnetic signal. The power generating circuitry may reside in one of the first or second substrates. Alternatively, the power generating circuitry may reside on a third substantially spherical semiconductor substrate coupled to at least one of the first or second substrates.
The transponder of the disclosed architecture is encapsulated in a biologically inert coating. In the ingestible embodiment, the transponder is small enough to be ingested easily, but not so small as to be absorbed by phagocytosis through the microvilli in the lining of the digestive tract. Preferably, the transponder of the present invention is approximately one millimeter in diameter.
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patent: 5446452 (1995-08-01), Litton
patent: 5697384 (1997-12-01), Miyawaki et al.
patent: 5724030 (1998-03-01), Urbas et al.
patent: 5984875 (1999-11-01), Bruno
patent: 6015390 (1998-06-01), Krag
Ahn Samuel S.
Ahn Suzanne I.
Gaffney F. Andrew
Hays Steven R.
Ishikawa Akira
Ball Semiconductor Inc.
Howison, Chauza, Thoma, Handley & Arnott, L.L.P.
O'Connor Cary
Wingood Pamela
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