Protective circuitry for external sensing applications
AssigneeApple Inc.
InventorsPriyank Dineshbhai Patel, Nilay D. Jani
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Abstract
Galvanic corrosion of an external electrode of a physiological signal sensor (e.g., ECG sensor) can be reduced. In some examples, protective circuitry, such as a switching circuit, can be used to reduce galvanic corrosion. In a first mode of operation (e.g., corresponding to measurement by the physiological signal sensor), the switching circuit can provide a low-impedance path (e.g., from an external electrode to ground). In a second mode of operation (e.g., corresponding to non-measurement by the physiological sensing system), the switching circuit can provide a high-impedance path to reduce leakage currents (e.g., between the external electrode and ground), and thereby reduce galvanic corrosion.
Claims19
A wearable device comprising:
- an external electrode disposed on an external surface of the wearable device configured to contact skin on a wrist, wherein the external electrode is a ground electrode;
- sensing circuitry configured to sense a physiological signal via one or more electrodes including the external electrode;
- and
- a switching circuit coupled between the external electrode and a node at a voltage, wherein the node is a system ground node, the switching circuit configured to:
- in a first mode of operation associated with sensing the physiological signal, provide a low-impedance path between the external electrode and the node;
- and
- in a second mode of operation different from the first mode of operation, provide a high-impedance path between the external electrode and the node.
A method comprising:
- at a wearable device including an external electrode disposed on an external surface of the wearable device configured to contact skin on a wrist and a switching circuit coupled between the external electrode and a node of the wearable device at a voltage, wherein the external electrode is a ground electrode and the node is a system ground node:
- in a first mode of operation associated with sensing a physiological signal via the external electrode, providing a low-impedance path between the external electrode and the node;
- and
- in a second mode of operation, providing a high-impedance path between the external electrode and the node.
A non-transitory computer readable storage medium storing instructions, which when executed by one or more processing circuits of a wearable device including an external electrode disposed on an external surface of the wearable device configured to contact skin on a wrist and a switching circuit coupled between the external electrode and a node of the wearable device at a voltage, wherein the external electrode is a ground electrode and the node is a system ground node, cause the one or more processing circuits to:
- in a first mode of operation associated with sensing a physiological signal via the external electrode, operate the switching circuit as a closed circuit between the external electrode and the node;
- and
- in a second mode of operation different from the first mode of operation, operating the switching circuit as an open circuit between the external electrode and the node.
Dependencies are inferred from the claim text.