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EP-3534776-B1 - SENSOR HOUSING AND ASSOCIATED DISPOSABLE ELEMENT

EP3534776B1EP 3534776 B1EP3534776 B1EP 3534776B1EP-3534776-B1

Inventors

  • ALLEN, JOHN
  • BEALE, Thomas Anthony William
  • WIGHTMAN, James Patrick

Dates

Publication Date
20260506
Application Date
20171107

Claims (15)

  1. A sensing device (1) comprising a sensor housing (3) mounting sensor elements and a attachment member (4), the attachment member (4) comprising first (5) and second (6) components, the first component (5) configured to receive the sensor housing (3) therein and to permit rotational movement between the attachment member (4) and the sensor housing (3) and to restrict relative movement between the attachment member (4) and the sensor housing (3) in the axial direction of the sensor housing (3), and the second component comprising a flexible membrane (6) that is attachable to an underside of the first component (5), the flexible membrane (6) extending at least in part beyond an outer edge of the first component (5), the flexible membrane (6) comprising attachment means for attachment of the attachment member (4) to a patient, and wherein the attachment member (4) is adapted to allow passage of radiation from the sensor housing (3) to the patient, and wherein the flexible membrane (6) comprises an upper side and an underside, and wherein, in use, the underside of the flexible membrane (6) is in contact with the patient's skin, and includes means for attachment to the patient's skin, and the upper side of the flexible membrane engages with the underside of the first component of the attachment member, and the sensor housing exerts a force on the patient's skin.
  2. A sensing device according to Claim 1, wherein the attachment means comprises at least one of the group consisting of: a hook and loop type fastener; and an adhesive surface at least to the side of the flexible membrane (6) that is distal from the first component (5).
  3. A sensing device according to Claim 2, wherein the adhesive of the adhesive surface to the side of the flexible membrane (6) that is distal from the first component (5) has an adhesion within a certain range, and adhesion is defined by a peel adhesion strength to steel selected from the group consisting of: 0.1kg/25mm width to 1kg/25mm width; and 0.125kg to 0.6kg/25mm width.
  4. A sensing device according to any of Claims 1 to 3, wherein the part of the flexible membrane (6) that extends beyond the outer edge of the first component (5) comprises a plurality of tabs (6b).
  5. A sensing device according to any preceding claim, wherein the attachment member (4) comprises a third component (8) in the form of clip means, wherein the third component (8) is shaped and dimensioned to receive the first component (5) in a push-fit arrangement, and wherein, in use, the flexible member (6) is located in-between the first component (5) and the third component (8), such that the third component (8) attaches the flexible membrane (6) to the underside of the first component (5).
  6. A sensing device according to any of Claims 1 to 4, wherein the flexible membrane (6) is attached to the underside of the first component (5) by means selected from the group consisting of adhesive and welding.
  7. A sensing device according to any preceding claim, wherein the flexible membrane (6) comprises two flexible layers, a first layer for attachment to the underside of the first component (5) and a second layer attached to the first layer and for attachment to the skin of a patient.
  8. A sensing device according to Claim 7, wherein the adhesion of the surfaces of the first layer is defined by a peel adhesion to low density polyethylene (LDPE) in the range of 1.1 to 1.5 kg/25.4mm.
  9. A sensing device according to any of Claims 1 to 8, wherein the flexible membrane provides an unbroken surface.
  10. A sensing device according to any of Claims 1 to 9, wherein the flexible membrane at least in the region where radiation is to pass exhibits low absorption of the wavelength(s) of radiation emitted and sensed by components housed in the sensor housing.
  11. A sensing device according to any preceding claim, wherein the flexible membrane includes a hole situated substantially centrally therein.
  12. A sensing device according to any preceding claim, wherein the first component comprises a plurality of clips which are resilient and which are so shaped and dimensioned as to grip the sensor housing when the sensor housing is mounted within the clips, and wherein the clips are sufficiently resilient to allow the sensor housing to ride over free ends of the clips when the sensor housing is pressed into or out of the first component of the attachment member.
  13. A sensing device according to any preceding claim, wherein the first component of the attachment member includes a protruding part extending from the base of said attachment member, the protruding part formed of a material that exhibits low absorption of wavelengths of radiation emitted and sensed by components housed in the sensor housing.
  14. A sensing device according to Claim 11 or claim 10 or 12 when dependent on Claim 9, wherein the first component of the attachment member includes a hole configured to receive a protruding part of the sensor housing; or wherein the first component of the attachment member includes a hole configured to receive a protruding part of the sensor housing and wherein, when the sensor housing is mounted in the first component of the attachment member, the protruding part of the sensor housing extends through the hole in the first component; or wherein the first component of the attachment member includes a hole configured to receive a protruding part of the sensor housing and wherein the protruding part of the sensor housing extends beyond the surface of the first component that is distal from the sensor housing.
  15. A sensing device according to Claim 14, wherein the flexible membrane is attached to the underside of the first component around the hole and the flexible membrane covers the hole.

Description

Field of the Invention The present invention relates to a medical sensor housing and in particular to an optical sensor housing for use in reflection mode photoplethysmography. Background of the Invention The technique of contact photoplethysmography (PPG) is used inter alia in the assessment of peripheral arterial disease. The technique requires optical sensor housings to be attached to the skin of a patient. Light emitted by a near infra-red emitter or an emitter emitting visible wavelength green or red light is scattered and absorbed by the microvasculature of the patient's body at the position of attachment of the sensor housing and back-scatter detected by an adjacent detector or set of detectors located within the sensor housing, the detector configured to detect the wavelength of light emitted by the emitter. PPG sensors are classified as either transmission mode or reflection (also known as adjacent) mode. It is known that reflection mode PPG can offer much more flexibility in where the sensor can be placed on the skin surface than do transmission mode sensors. The sensor housings used in photoplethysmography are typically attached to the extremities of the patient's body, for example to the great toe / finger pad and ear lobe where pulses can usually be sensed easily. The most used sensor housings are in the form of a clip. One such clip is described in WO97/20497. Typically, such clips are intended for reuse. To optimise the effectiveness of the photoplethysmography technique the applicants have found that applying a controlled pressure on the skin can be beneficial. Where the sensor exerts a controlled pressure on the skin, movement artefacts in the sensor output signal are reduced and probe amplitude increase is possible. US2014/0303462 describes a device for applying a sensor to a measurement site on a patient's skin. US2012/0330126 describes a monitoring device for attachment to a patient's skin. US6345191 describes a sensor device which includes a sensor film applied to the skin and a CCD camera. US4274418 describes a sensor housing for attachment to a patient's skin using an adhesive membrane. US4303076 describes a probe for transcutaneous blood gas analysis. Summary of the Invention According to the disclosure there is provided a sensing device comprising a sensor housing mounting sensor elements and an attachment member, the attachment member comprising first and second components, the first component configured to receive the sensor housing therein and to permit rotational movement between the attachment member and the sensor housing and to restrict relative movement between the attachment member and the sensor housing in the axial direction of the sensor housing, and the second component comprising a flexible membrane that is attachable to an underside of the first component, the flexible membrane extending at least in part beyond an outer edge of the first component, the flexible membrane comprising attachment means for attachment of the attachment member to a patient, and wherein the attachment member is adapted to allow passage of non-ionising radiation from the sensor housing to the patient. Preferably, the non-ionising radiation is optical radiation or ultrasound radiation. The attachment means may comprise at least one hook and loop type fastener. Alternatively, the attachment means may comprise an adhesive surface at least to the side of the flexible membrane that is distal from the first component. The adhesive of the adhesive surface to the side of the flexible membrane that is distal from the first component preferably has an adhesion within a certain range, and adhesion is defined by a peel adhesion strength to steel in the range of 0.1-1.0kg/25mm width when adhered to steel (as measured using 3M measurement procedure "Adhesion to Steel, 180deg peel"). More preferably, the adhesion defined by a peel adhesion strength to steel is within the range 0.125kg/25mm width to 0.6kg/25mm width. Preferably, the part of the flexible membrane that extends beyond the outer edge of the first component comprises a plurality of tabs and more preferably at least two tabs, and still more preferably four tabs. The tabs may be spaced equidistantly. Where four tabs are provided they may be provided in pairs, each tab of a pair lying on the same axis. One pair of tabs may be more flexible than the other. For example, the tabs that are for wrapping around the digit may be very flexible, whereas the other pair of tabs may be relatively stiff. The tabs may include a series of graduated markings to aid placement of the device on the patient. The attachment member may comprise a third component in the form of clip means, wherein the third component is shaped and dimensioned to receive the first component in a push-fit arrangement, and wherein, in use, the flexible membrane is located in-between the first component and the third component. Where the attachment member includes a third component, the flexib