RELATED APPLICATION

This application was originally filed as Patent Cooperation Treaty Application No. PCT/FI2015/050855 filed Dec. 7, 2015 which claims priority benefit to EP Patent Application No. 14199095.2, filed Dec. 19, 2014.

TECHNICAL FIELD

The present application generally relates to biometric measurement. In particular, but not exclusively, the present application relates to a wearable apparatus for biometric measurement. In particular, but not exclusively, the present application relates to a skin attached apparatus for biometric measurement.

BACKGROUND

This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

Wearable devices for biometric measurements are increasingly sought after and produced. Currently many devices for measuring e.g. heart rate and further biometrics are uncomfortable and bulky, i.e. not suitable or convenient to be worn for prolonged time periods.

Existing devices using optical measurement methods, such as optical photoplethysmography (PPG), are worn in contact with the skin, for example on the wrist, which is more convenient for long term use. These devices rely on illuminating the body tissue with for example IR, red, or green light emitting diodes (LEDs) and detecting the reflected light signal.

In order to attain a sufficient signal, the illumination needs to be very bright, which causes increased power consumption, and the devices need to be worn uncomfortably tightly on the skin in order to avoid artifacts due to relative movement of the skin and the measurement components.

Devices attached to the skin, akin to plasters or band aids, are known for optical biometric measurement. Such devices need to be small in size and accordingly the power source thereof is limited in size as well causing short usage times.

The present invention aims to mitigate the problems of optical biometric measurement.

SUMMARY

Various aspects of examples of the invention are set out in the claims.

According to a first example aspect of the present invention, there is provided an apparatus, comprising:

at least one light source;

at least one photodetector;

a first layer of optical material configured to embed the at least one light source; and

a second layer of optical material configured to embed the at least one photodetector; wherein

the first and second layer of optical material are configured to guide light from the at least one light source and to prevent the light from the at least one light source directly reaching the at least on photodetector; and wherein

the second layer of optical material is configured to guide light towards the at least one photodetector.

The apparatus may further comprise a substrate on which the at least one light source and the at least one photodetector are mounted.

The substrate may be flexible and/or stretchable.

The at least one photodetector may be mounted on a distance from the surface of the substrate.

The at least one light source may comprise a light emitting diode, LED.

The at least one light source may comprise an ambient light source.

The apparatus may further comprise a reflective layer and an optical element configured to function as a waveguide.

The first and/or second layer of optical material may comprise reflective or absorbing material.

The apparatus may further comprise a skin safe adhesive layer configured to embed the elements of the apparatus and configured for attaching the apparatus to the skin of a user.

The apparatus may further comprise a circuit element comprising a low power amplifier circuit.

The low power amplifier circuit may be mounted on a separate circuit element.

According to a second example aspect of the present invention, there is provided a system, comprising

the apparatus of the first example aspect; and

a power and memory element connected to the apparatus.

The power and memory element may be comprised in an independent apparatus.

The independent apparatus may comprise a personal electronic device such as a wristwatch, a smart watch, an activity bracelet, a mobile phone, a smartphone, a tablet, a computer or a television.

According to a third example aspect of the present invention, there is provided a method of manufacturing an apparatus according to the first aspect of the invention, comprising

mounting at least one light source on a substrate;

applying a first layer of optical material to embed the at least one light source;

mounting at least one photodetector on a substrate; and

applying a second layer of optical material to embed the at least one photodetector.

The method may further comprise applying a layer of skin safe adhesive.

The at least one light source may be mounted on a first substrate and the at least one photodetector may be applied on a second substrate and mounted on top of the first substrate.

Any memory medium hereinbefore or hereinafter may comprise a digital data storage such as a data disc or diskette, optical storage, magnetic storage, holographic storage, opto-magnetic storage, phase-change memory, resistive random access memory, magnetic random access memory, solid-electrolyte memory, ferroelectric random access memory, organic memory or polymer memory. The memory medium may be formed into a device without other substantial functions than storing memory or it may be formed as part of a device with other functions, including but not limited to a memory of a computer, a chip set, and a sub assembly of an electronic device. In the context of this document, a “memory medium” may be any non-transitory media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

Different non-binding example aspects and embodiments of the present invention have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in implementations of the present invention. Some embodiments may be presented only with reference to certain example aspects of the invention. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

