US-12622643-B2 - Fixing of a sensor to a body part for measurement of a body parameter

Abstract

A device is for measuring a body parameter for a subject. The device comprises a sensor for measuring the body parameter, a housing element for positioning the sensor on a body part of the subject and an actuator system within the housing element for applying a pressure to the body part. The actuator system comprises two states, a first state based on the actuator system applying a first pressure to a first area of the body part and a second state based on the actuator system applying a second pressure to a second area of the body part. The device also comprises a controller configured to apply the first and second states at different times.

Inventors

• Eduard Gerard Marie Pelssers
• Hans Willem Van Kesteren
• Jens Muehlsteff
• RALPH WILHELM CHRISTIANUS GEMMA ROSA WIJSHOFF
• ANTHONIUS PETRUS GERARDUS EMANUELS JANSSEN

Assignees

• KONINKLIJKE PHILIPS N.V.

Dates

Publication Date

20260512

Application Date

20220302

Claims (15)

1. 1 . A device for measuring a body parameter for a subject while fixing itself to a body part of the subject, the device comprising: a sensor for measuring the body parameter; a housing element for positioning the sensor on the body part of the subject; an actuator system within the housing element for fixing the device to the body part of the subject by applying a pressure to a body location of the body part for fixing the housing, wherein the actuator system comprises two states: a first state based on the actuator system applying a first pressure to a first area of the body part; and a second state based on the actuator system applying a second pressure to a second area of the body part different to the first area, such that the first area has a relief from the first pressure while the second pressure is applied to the second area; and a controller configured to apply the first and second states at different times such that applied pressure is alternately positioned at said different areas of the body part.
2. 2 . The device of claim 1 , wherein the actuator system comprises at least two actuator elements, each actuator element being configured to change in volume or shape when the actuator element is stimulated, and wherein the controller is further configured to stimulate the actuator elements to define the state of the actuator system.
3. 3 . The device of claim 2 , wherein the actuator elements are based on electro active polymers configured to expand in volume when a voltage is applied and wherein the controller is further configured to apply a voltage to the electro active polymers.
4. 4 . The device of claim 2 , wherein the actuator elements are inflatable elements configured to expand when they are inflated.
5. 5 . The device of claim 4 , further comprising a pump for inflating the inflatable elements and wherein the controller is further configured to actuate the pump.
6. 6 . The device of claim 1 , wherein the controller is further configured to change the pressure applied to the body part of the subject by the actuator system.
7. 7 . The device of claim 6 , further comprising an accelerometer for determining the position of the subject and wherein the controller is further configured to change the pressure applied to the body part of the subject by the actuator system based on the position of the subject.
8. 8 . The device of claim 1 , wherein the sensor is a pulse oximeter which comprises an LED unit and a photodetector, wherein the photodetector is configured to obtain a signal relating to the saturation percentage of oxygen in blood.
9. 9 . The device of claim 8 , wherein the LED unit is placed at the extremity of a first actuator element and the photodetector is placed at the extremity of a second actuator element.
10. 10 . The device of claim 8 , wherein the controller is further configured to control the actuator system to apply a pre-determined pressure to the body part, wherein the application of the pre-determined pressure to the body part reduces the venous contribution to the signal obtained by the photodetector.
11. 11 . The device of claim 1 , further comprising an adhesive layer at the interface between the housing element and the body part of the subject and wherein the actuator system is configured to apply a pressure between the sensor and the body part.
12. 12 . The device of claim 1 , wherein the actuator system comprises: a rotating element with two or more protrusions, wherein the controller is configured to rotate the rotating element when changing states; and an elastic layer between the rotating element and the body part of the subject.
13. 13 . The device of claim 1 , further comprising a friction enhancing layer at the interface between the device and the body part of the subject.
14. 14 . The device of claim 1 , further comprising a moisture trapping element at the interface between the device with the body part of the subject for reducing moisture build up at said interface.
15. 15 . A method for measuring a body parameter for a subject with a device comprising a sensor, the method comprising: applying a first pressure to a first area of a body part using an actuator system, wherein the actuator system is within a housing element of the device and wherein the housing element is fixed thereby to the body part; applying a second pressure to a second area of the body part, different to the first area of the body part such that the first area has a relief from the pressure while the second pressure is applied to the second area, using the actuator system at a different time to the first pressure being applied to the first area of the body part such that applied pressure is alternately positioned at said different areas of the body part; and measuring the body parameter with a sensor which is positioned on the body part by the housing element.

Description

CROSS-REFERENCE TO PRIOR APPLICATIONS This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2022/055196, filed on Mar. 2, 2022, which claims the benefit of U.S. Provisional Application No. 63/157,228 filed on Mar. 5, 2021. These applications are hereby incorporated by reference herein. FIELD OF THE INVENTION The invention relates to a device for fixing to a body part of a subject. In particular, the invention relates to a device for measuring a body parameter of a subject whilst fixing itself to a body part of the subject. BACKGROUND OF THE INVENTION Pulse oximetry is a well known method to measure the saturation of hemoglobin with Oxygen. The associated sensor is a SpO2 sensor. Hemoglobin is a component of red blood cells and these cells are present in blood which flows through arteries, blood capillaries and veins. This method uses two light emitting diodes (LEDs) of different wavelengths and the light transmission is measured by a photodetector. From the pulsatile part of the transmitted light, a heart rate and a ratio between hemoglobin with bound Oxygen and without bound Oxygen can be determined. Ideally, the measured saturation of oxygen reflects the arterial Oxygen saturation. The two LEDs and photodetector are integrated into a housing. These LEDs and optical detector are wired and these wires are collected into one cable. The cable is a shielded cable and may even consist of additional shields, for instance, around the wires to the detector and one around the wires to the LEDs. The other end of the cable is terminated by a connector that can be coupled to a patient monitoring instrument (Patient Monitor). The Patient Monitor supplies a voltage to both LEDs and reads the signal from the photodetector. SpO2 sensors can be placed on different human body locations, such as the finger, nostril, forehead or ear. Fixing is carried out by exerting a pressure on the body location. There are reusable sensors that have a hollow elastic housing exerting continuous pressure on the body location such as a finger. Others employ a more rigid housing with a hinge and spring, again exerting a continuous pressure on a body location. In addition, disposable SpO2 sensors consist of a flexible material on which LEDs and detector are mounted. This flexible material is wrapped around the finger for fixing the sensor to the finger and can also exert a pressure on the finger. Besides providing fixing, pressure on the SpO2 sensor can also be used to suppress or reduce the contribution of pulsating venous blood and tissue fluid on the SpO2 signal. SpO2 sensors for the finger have been available for many years. However, there is a compliance issue with users that remove the SpO2 sensor from the finger. The SpO2 sensor exerts a continuous pressure on the finger and consequently several users experience an uncomfortable feeling. Additionally, other sensors on other body locations (with sufficient blood perfusion for reliable measurement) fixed by exerting a continuous pressure can induce an uncomfortable feeling. The effect of continuous pressure is a constant stimulation of nerves in the skin, which is translated to uncomfortable feeling by the brain. The blood flow is also partially restricted, generating further uncomfortable feelings. Complete blood flow restriction can even lead to local necrosis. This has been observed in forehead SpO2 sensors fixed with a stretched elastic band. It is often a challenge to find a suitable balance between sufficient pressure for accurate measurements and low enough pressure to be comfortable and guarantee sufficient blood flow even for users with blood perfusion issues. Thus, there is a need for an improvement in comfort, and thus subject compliance, for devices which require (or benefit from) fixing of the device to a body part for the measurement of a body parameter (e.g. heart rate, blood pressure, oxygen saturation in blood, etc.). SUMMARY OF THE INVENTION The invention is defined by the claims. According to examples in accordance with an aspect of the invention, there is provided a device for measuring a body parameter for a subject, the device comprising: a sensor for measuring the body parameter;a housing element for positioning the sensor on a body part of the subject;an actuator system within the housing element for applying a pressure to the body part, wherein the actuator system comprises two states: a first state based on the actuator system applying a first pressure to a first area of the body part; anda second state based on the actuator system applying a second pressure to a second area of the body part; and a controller configured to apply the first and second states at different times. For example, devices used for measuring the saturation percentage of oxygen in blood (a SpO2 device) typically have compliance problems with subjects which find these devices uncomfortable and move or remove the de