Wearable cardioverter defibrillator with improved ECG electrodes
A Wearable Cardioverter Defibrillator (WCD) system comprises an electrode assembly with a permeable ECG electrode and a moisture barrier. In some embodiments, the moisture barrier is configured to reduce drying out of the permeable ECG electrode to improve performance of the WCD system. In a further enhancement, some embodiments of the electrode assembly also include a pillow structure positioned on a non-skin-contacting surface of the electrode assembly to comfortably reduce movement artifact or noise in the received ECG signal.
1 . A Wearable Cardioverter Defibrillator (WCD) system, the WCD system comprising:
a support structure configured to be worn by a patient;
a power source configured to store electrical charge;
a discharge circuit coupled to the power source;
one or more electrode assemblies, each electrode assembly of the one or more electrode assemblies, having an electrode, the electrode having at least a skin-facing surface and a non-skin-facing surface, wherein the electrode of each electrode assembly comprises a plurality of layers, each layer of the plurality of layers having an impedance depending on thickness and material of the layer, and wherein the electrode comprises insulating material at least partially surrounding the plurality of layers at least on two sides except for the skin-facing surface of the electrode;
wiring comprising one or more wires, wherein the wiring is configured to couple the one or more electrode assemblies and one or more processors, wherein the wiring is configured to stretch with the support structure, and wherein a creepage distance is maintained across the plurality of layers using the insulating material across each of the plurality of layers except the layer having the skin-facing surface, to prevent arcing in the one or more electrode assemblies during defibrillation;
a plurality of electrode status indicators, wherein each electrode status indicator of the plurality of electrode status indicators is proximate to an electrode assembly of the one or more electrode assemblies and is configured to activate when the WCD system detects a fault; and
the one or more processors configured to receive an electrocardiogram (ECG) signal from the one or more electrode assemblies, wherein the one or more processors, based on the received ECG signal, make a shock decision or a no shock decision, and wherein responsive to the shock decision, a shock process is initiated to cause the discharge circuit and the power source to enable, at least, a portion of electrical charge stored in the power source to be delivered to the patient, and responsive to the no shock decision, the discharge circuit and the power source are controlled to prevent delivery of the electrical charge stored in the power source to the patient.
2 . The WCD system of claim 1 , wherein the wiring is configured into an alternating pattern such that stretching the support structure elongates the wiring without distorting the wiring.
3 . The WCD system of claim 2 , wherein the alternating pattern is a triangular zig-zag pattern, a substantially sinusoidal wave pattern, or a combination thereof.
4 . The WCD system of claim 1 , wherein the one or more wires do not overlay each other.
5 . The WCD system of claim 1 , wherein the moisture barrier is located on or adjacent to the non-skin-facing surface of the electrode.
6 . The WCD system of claim 1 , wherein the wiring is configured to allow a fabric garment to stretch without distortion.
7 . The WCD system of claim 1 , wherein the WCD system further comprises one or more attachment points configured to connect the wiring to the support structure where the one or more wires change direction.
8 . The WCD system of claim 7 , wherein the one or more attachment points secure the one or more wires to the support structure without slack.
9 . The WCD system of claim 1 , further comprising a connector configured to connect the wiring and the electrode assembly.
10 . The WCD system of claim 9 , wherein the connector is a washable hermetic connector.
11 . The WCD system of claim 1 , wherein the electrode comprises a permeable electrode.
12 . The WCD system of claim 1 , wherein the fault is high impedance of an electrode due to skin dryness.
13 . The WCD system of claim 1 , wherein the plurality of electrode status indicators are light emitting diodes (LEDs).
14 . The WCD system of claim 1 , wherein the electrode of each electrode assembly is coupled to a respective wire of the one or more wires.
15 . The WCD system of claim 1 , wherein the skin-facing surface comprises a silver portion.
16 . The WCD system of claim 15 , wherein the silver portion is formed with a plurality of openings that are configured to permit airflow.
17 . The WCD system of claim 1 , wherein the electrode is a two-layer electrode with a first layer interfaced to a skin of the patient and a second layer positioned adjacent to the first layer.
18 . The WCD system of claim 17 , wherein the impedance and/or thickness of the first layer is different from the impedance and/or thickness of the second layer.
19 . The WCD system of claim 1 , wherein the plurality of layers include a high-impedance layer having a value of impedance in a range between 1 kΩ and 100 kΩ.
20 . The WCD system of claim 1 , wherein the skin-facing surface of the electrode is substantially circular in shape, and wherein the skin-facing surface has a diameter in a range from 0.75 inches to 1.25 inches.