Body function measuring apparatus

Abstract

body function measuring apparatus which provides: (1) an indication of the body function being measured, and (2) a loose probe condition by determining that the difference between the rate of change of a first body function signal, developed by a first sensor in the probe, and the rate of change of a second body function signal, developed by a second sensor in the probe, exceeds a predetermined threshold.

Description

TECHNICAL FIELD

The present invention relates, in general, to the measurement of body functions with sensors in contact with the skin of a human being and, in particular, to a unit which, in addition to measuring a body function, provides an indication when the sensor in contact with the skin becomes dislodged from the skin. Although the present invention will be described in connection with skin temperature measurement, it will be apparent that the present invention has broader application.

BACKGROUND OF THE INVENTION

Many probes are in use today to measure or monitor a function of the body with which the probe is in contact or to control or influence a body state or condition. For example, a signal representative of the skin temperature of an infant in an incubator can be used to display the of the infant and can be used to control the incubator heater to regulate the thermal environment of the incubator. In such an application, it is important that intimate contact between the skin and the probe contact surface which carries the temperature sensor be established and maintained. Should the probe become dislodged, resulting in a total or partial loss of contact, the temperature indication will be incorrect and the control of the incubator heater will be other than what is desired, quite possibly leading to dangerous consequences.

Many loose probe indicators have been suggested or put into actual use. Some are based on using the signals representative of the body function being measured to detect a loose probe condition. Others are based on directly measuring some characteristic of the contact, such as impedance, which changes as the contact changes. Yet others incorporate in the probe special sensors, for example optical sensors, which detect changes in the position of the probe relative to the of the thermistors which would cause a significant difference between the first temperature signal T₁ and the second temperature signal T₂.

While there have been described preferred embodiments of the present invention, it should be obvious to those skilled in the art that various modifications and changes can be made without departing from the true spirit and scope of the invention.

Claims

1. skin temperature measuring apparatus comprising:

a housing;

first and second identical thermistors temperature sensors spaced apart in said housing but in proximity to each other and adapted for contact with generally the same area of skin for developing first and second temperature signals, respectively; and

means responsive to said first temperature signal and said second temperature signal for:

(a) developing an indication of the temperature at the skin with which said first thermistor and said second thermistor temperature sensors are in contact, ; and

(b) detecting a difference between the rate of change of said first temperature signal and the rate of change of said second temperature signal which exceeds a predetermined threshold representing a difference in the proximity of said first thermistor temperature sensor to the skin and the proximity of said second thermistor temperature sensor to the skin, and

a flexible substrate on which said first and said second temperature sensors are mounted.

2. skin temperature measuring apparatus according to claim 1 further including means responsive to said first temperature signal and second temperature signal for detecting a difference between said first temperature signal and said second temperature signal which exceeds a predetermined threshold representing a failure of one of said first thermistor and said second thermistor temperature sensors.

3. skin temperature measuring apparatus according to claim 3 further including a flexible substrate on which said first thermistor and said second thermistor are mounted.

4. skin temperature measuring apparatus according to claim 3 1 wherein said substrate has:

(a) first and second lands on which said first thermistor and said second thermistor temperature sensors, respectively, are mounted, and

(b) a neck extending between said first land and said second land and having a width narrower than the width of said first land and said second land.

5. body function measuring apparatus comprising:

a housing;

first and second identical sensors spaced apart in said housing but in proximity to each other and adapted for contact with generally the same area of skin for developing first and second body function signals, respectively; and

means responsive to said first body function signal and said second body function signal for:

(a) developing an indication of the body function at the skin with which said first sensor and said second sensor are in contact, and

(b) detecting a difference between the rate of change of said first body function signal and the rate of change of said second body function signal which exceeds a predetermined threshold representing a difference in the proximity of said first sensor to the skin and the proximity of said second sensor to the skin; and

flexible substrate on which said first sensor and said second sensor are mounted.

6. body function measuring apparatus according to claim 5 further including means responsive to said first body function signal and said second body function signal for detecting a difference between said first body function signal and said second body function signal which exceeds a predetermined threshold representing a failure of one of said first sensor and said second sensor.

7. body function measuring apparatus according to claim 5 further including a flexible substrate on which said first sensor and said second sensor are mounted.

8. body function measuring apparatus according to claim 7 5 wherein said substrate has:

(a) first and second lands on which said first sensor and said second sensor, respectively, are mounted, and

(b) a neck extending between said first land and said second land and having a width narrower than the width of said first land and said second land.

9. A skin temperature measuring apparatus comprising:

a housing;

at least a first and second temperature sensor spaced apart in said housing, but in proximity to each other and adapted for contact with generally the same area of skin for developing first and second temperature signals, respectively, wherein the housing is provided with a flexible substrate on which the at least first and second temperature sensors are mounted;

a first indicator connected to one of said at least first and second temperature sensors to indicate the temperature of the skin; and

a second indicator connected to at least both of said at least first and second temperature sensors to produce an output indicating an improper sensing of the skin temperature at that same area by at least one of the at least first and second temperature sensors.

10. The skin temperature measuring apparatus of claim 9, wherein the second indicator produces an output when the temperatures sensed by the at least first and second temperature sensors differ by a threshold amount.

11. The skin temperature measuring apparatus of claim 10 having a third indicator connected to said at least first and second temperature sensors which produces an output indicating an improper sensing of the skin temperature when the rate of change of the temperature sensors differ by a second threshold amount.

12. The skin temperature measuring apparatus of claim 9, wherein the second indicator produces an output when the rate of change of temperatures sensed by the at least first and second temperature sensors differ by a threshold amount.

13. A body function measuring apparatus comprising

a first sensor providing a first signal,

a second sensor spaced apart from the first sensor, the second sensor being positioned to lie proximate the first sensor, the second sensor providing a second signal,

a circuit coupled to the first and second sensors, the circuit comparing the rate of change of the first signal to the rate of change of the second signal,

an indicator operatively coupled to the circuit to indicate whether the difference between the rate of change of the first signal and the rate of change of the second signal exceeds a threshold, and

a housing, the first sensor being received by the housing and the second sensor being received by the housing, wherein the housing is formed to include a first land and a second land, the first sensor being carried by the first land and the second sensor being carried by the second land.

14. The body function measuring apparatus of claim 13, wherein the housing is flexible.

15. The body function measuring apparatus of claim 13, wherein the housing is formed to include a neck connecting the first land to the second land.

16. The body function measuring apparatus of claim 15, wherein the neck is flexible so that the first land can move relative to the second land.