# US 2016/0256111 A1 · Electrical wearable capacitive biosensor and noise artifact suppression method

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- Number: US 2016/0256111 A1
- Document ID: US20160256111A1
- Status: Published application
- Kind: A1
- Application number: 15/031,142
- Filed: 2014-10-21
- Published: 2016-09-08
- Earliest claimed: 2013-10-22
- Assignees: The Regents of the University of California
- Applicants: The Regents of the University of California
- Inventors: Chung-Kuan Cheng; Patrick Mercier; Shih-Hung Weng
- Web page: https://patentgrep.com/patent/US20160256111A1

## CPC

- A61B 5/7203: {for noise prevention, reduction or removal}
- A61B 5/0002: {Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network (endoradiosondes A61B5/07)}
- A61B 5/28: for electrocardiography [ECG]
- A61B 5/302: for capacitive or ionised electrodes, e.g. metal-oxide-semiconductor field-effect transistors [MOSFET]
- A61B 5/6802: {Sensor mounted on worn items}
- A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)}
- A61B 2562/166: the sensor is mounted on a specially adapted printed circuit board
- A61B 2562/182: Electrical shielding, e.g. using a Faraday cage
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

A biosensor of the invention is a capacitive noncontact sensor with two sensor channels split into a plurality of physically interdigitated symmetrical electrodes and shield sections. Two capacitive plates are electrically connected to the two sensor channels. The capacitive noncontact sensor is sized and packaged to be worn by a person to place the capacitive plates close to the skin of the person and form first and second channel input capacitors with the skin. A signal reconstruction circuit obtains a bio signal from the first and second channel input capacitors through the electrodes by reconstructing differences in the two sensor channels. The circuit includes different parasitic input capacitance in the two channels to create channel-specific outputs that depend on input coupling capacitance.

## Claims

### Claim 1

A method for suppressing noise and recovering a biosignal of interest from a bio-sensor, the method comprising:
obtaining biosignals from two capacitor plates through two separate channels via separate sensor electrodes, wherein the two separate channels have different input load capacitances;
calculating input coupling capacitance for the bio-sensor using the different input load capacitances;
with the input coupling capacitance and a signal from one of the two channels, recovering the biosignal of interest.

### Claim 2 (depends on 1)

The method of claim 1, wherein the biosignals are obtained from a bio sensor that is a capacitive noncontact sensor with the two sensor channels split into symmetrically interdigitated electrode and shield sections.

### Claim 3 (depends on 1)

The method of claim 1, wherein the input coupling capacitance is determined as follows:
output of the two channels are calculated
V
1
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wherein Cp1 and Cp2 are the different input load capacitances, Q(t) is set as a constant representing charge at an amplifier input node, and then the input capacitance is determined
by
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Eq
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6.

### Claim 4

A bio sensor, comprising:
a plurality of symmetrical electrode sections in a first layer electrically connected to corresponding symmetrical shield sections in a second layer, wherein the symmetrical electrode sections and shield sections are arranged and connected to define at least two shielded electrode channels;
dielectric isolating electrode sections and shield sections of the at least two shielded electrode channels from each other;
at least two capacitor plates electrically connected to the two shielded electrode channels; and
packaging to protect the biosensor and permit the biosensor to be worn in a manner to place the two capacitor plates adjacent skin of a user.

### Claim 5 (depends on 4)

The bio sensor of claim 4, further comprising a signal layer within the packaging including a two channel signal amplifier, wherein the two shielded electrode channels provide input capacitances for the two channel signal amplifier.

### Claim 6 (depends on 5)

The bio sensor of claim 5, wherein the plurality of symmetrical electrode sections and corresponding symmetrical shield sections comprise pie shaped sections.

### Claim 7 (depends on 6)

The bio sensor of claim 6, further comprising vias connecting a first set of symmetrical electrode sections to corresponding symmetrical shield sections.

### Claim 8 (depends on 7)

The bio sensor of claim 7, further comprising an outer conductive ring connecting a second set of symmetrical electrode sections to corresponding shield sections.

### Claim 9 (depends on 1)

A bio sensor system including a biosensor of claim 1, and further comprising:
a module including a common noise reduction circuit and a communication module to communicate sensed biosignals to a portable computing device or computer.

### Claim 10

A bio sensor comprising:
a capacitive noncontact sensor with two sensor channels split into a plurality of physically interdigitated symmetrical electrodes and shield sections, two capacitive plates electrically connected to the two sensor channels, wherein the capacitive noncontact sensor is sized and packaged to be worn by a person to place the capacitive plates close to the skin of the person and form first and second channel input capacitors with the skin; and
a signal reconstruction circuit that obtains a bio signal from the first and second channel input capacitors through the electrodes by reconstructing differences in the two sensor channels, wherein the circuit includes different parasitic input capacitance in the two channels to create channel-specific outputs that depend on input coupling capacitance.