# US 11,439,356 B2 · Wireless and noninvasive epidermal electronics

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- Number: US 11,439,356 B2
- Document ID: US11439356B2
- Status: Granted
- Kind: B2
- Application number: 17/568,771
- Filed: 2022-01-05
- Published: 2022-04-28
- Granted: 2022-09-13
- Earliest claimed: 2018-03-30
- Assignees: Northwestern University
- Applicants: Northwestern University
- Inventors: John A. Rogers; Siddharth Krishnan; Tyler R. Ray; Amit B. Ayer; Philipp Gutruf; Jonathan T. Reeder; Kun Hyuck Lee; Chun-Ju Su
- Web page: https://patentgrep.com/patent/US11439356B2

## CPC

- A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals}
- A61B 5/00: Measuring for diagnostic purposes (radiation diagnosis A61B6/00; diagnosis by ultrasonic, sonic or infrasonic waves A61B8/00); Identification of persons
- A61B 5/01: Measuring temperature of body parts {; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue} (clinical contact thermometers G01K13/20)
- A61B 5/026: Measuring blood flow {(A61B3/1233, A61B3/1241 take precedence)}
- A61B 5/031: {Intracranial pressure}
- A61B 5/145: Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value {; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue} (non-radiation detecting or locating of foreign bodies in blood A61B5/06)
- A61B 5/14507: {specially adapted for measuring characteristics of body fluids other than blood (devices for taking samples of body liquids A61B10/0045)}
- A61B 5/4851: {Prosthesis assessment or monitoring}
- A61B 2562/0271: Thermal or temperature sensors
- A61B 2562/028: Microscale sensors, e.g. electromechanical sensors [MEMS]
- A61B 2562/046: in a matrix array
- A61B 2562/164: the sensor is mounted in or on a conformable substrate or carrier
- A61B 2562/18: Shielding or protection of sensors from environmental influences, e.g. protection from mechanical damage
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Provided are conformable devices to measure subdermal fluid flow and related methods. A soft, stretchable and flexible substrate supports a thermal actuator and various specially positioned temperature sensors. A microprocessor in electronic communication with sensors calculates subdermal fluid flow from the measured upstream and downstream temperatures, as well as various application-dependent parameters. Devices and methods provided herein are particularly useful for measuring cerebral spinal fluid in a ventricular shunt placed for treatment of hydrocephalus.

## Claims

### Claim 1

A device to measure a subdermal fluid flow parameter comprising:
a substrate;
at least one upstream temperature sensor supported by the substrate;
at least one downstream temperature sensor supported by the substrate; and
a thermal actuator supported by the substrate and positioned between said upstream temperature sensor and said downstream temperature sensor;
wherein the thermal actuator comprises an array of resistors having a cumulative resistivity sufficient to provide for thermal actuation such that the upstream temperature sensor measures an upstream temperature and said downstream temperature sensor measures a downstream temperature to allow determination of said subdermal fluid flow parameter; and wherein the array of resistors of the thermal actuator provides a fill factor selected from the range of 10% to 60% of an area between said upstream temperature sensor and said downstream temperature sensor.

### Claim 2 (depends on 1)

The device of claim 1, further comprising a microprocessor in electronic communication with the downstream temperature sensor and the upstream temperature sensor to calculate subdermal fluid flow parameter from the measured upstream and downstream temperatures.

### Claim 3 (depends on 1)

The device of claim 1, wherein said area between said upstream temperature sensor and said downstream temperature sensor is 5%-60% of total printed circuit board footprint area of the device.