Photoplethysmography sensors and processes
The present disclosure relates to devices and processes that produce superior photoplethysmography (PPG) signals. In various embodiments, the present devices and processes leverage load backing, conformal contact, and strain isolation mechanisms to produce higher quality and amplitude PPG signals, and provide more repeatable results than previous devices and processes. In at least one embodiment, the devices discussed herein include a rigid support structure and elastic spacer for supporting a PPG sensor and various adhesive layers.
1. A patch comprising:
a silicone-based adhesive layer defining a silicone-based adhesive layer opening and comprising a first side and a second side;
an acrylic-based adhesive layer connected to the first side of the silicone-based adhesive layer, wherein the acrylic-based adhesive layer is exposed on the second side of the silicone-based adhesive layer through the silicone-based adhesive layer-before opening;
a rigid support structure comprising:
an enclosure for housing a compressible spacer; and
a bottom surface area defining a rigid support structure opening for a photoplethysmography (PPG) sensor; and
the PPG sensor comprising:
a first side and a second side, the first side opposite the second side; and
the compressible spacer located within the enclosure and comprising a top portion operatively connected to a top surface of the enclosure opposite the bottom surface area and a bottom portion operatively connected to the first side of the PPG sensor, wherein when the patch is attached to a patient's skin:
the second side of the PPG sensor is in contact with the patient's skin;
the compressible spacer is between the first side of the PPG sensor and the rigid support structure within the enclosure such that the top portion of the compressible spacer is connected to the top surface of the enclosure and opposite the bottom portion of the compressible spacer connected to the first side of the PPG sensor, thereby enabling movement of the PPG sensor when the second side of the PPG sensor is in contact with the patient's skin;
the silicone-based adhesive layer attaches to a first portion of the patient's skin; and
the acrylic-based adhesive layer attaches to a second portion of the patient's skin, the second portion of the patient's skin corresponding to at least a portion of the bottom surface area of the rigid support structure extending through the silicone-based adhesive layer opening.
2. The patch of claim 1 , wherein the patch comprises a vertical distance between the second side of the PPG sensor and the bottom surface area of the rigid support structure.
3. The patch of claim 2 , wherein, when attached to the patient's skin, the second side of the PPG sensor is pressed into the patient's skin.
4. The patch of claim 3 , wherein, when the patch is attached to the patient's skin, the patch on the patient, when the PPG sensor is pressed into the patient's skin, exerts an amount of pressure which is at least partially based on the vertical distance.
5. The patch of claim 4 , wherein the vertical distance is 10 mm or less.
6. The patch of claim 1 , wherein the compressible spacer is elastic.
7. The patch of claim 6 , wherein the compressible spacer is silicone.
8. The patch of claim 7 , wherein the compressible spacer is porous.
9. The patch of claim 1 , further comprising a flexible printed circuit board (PCB) connected to the first side of PPG sensor.
10. The patch of claim 9 , wherein the PCB collects signal data from the PPG sensor.
11. The patch of claim 10 , wherein the data from the PPG sensor is transmitted to a computing system.