Fluid-Impermeable Dielectric Layer for Wearable Light Sensors
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Solution Overview
Problem
There is a need for reliable, cost-effective sensor devices that can monitor patients' health remotely, particularly for medical professionals, and existing light-based sensors face challenges in durability and consistency when attached to the body for long periods, especially due to mechanical deformation during patient movement.
Innovation Solution
The development of an apparatus with a light emitter and photodetector formed on a single fluid-permeable substrate, featuring a channel member, source and drain electrodes, photosensitive material, and a gate electrode, along with a layer of fluid-impermeable dielectric material that inhibits electrical current flow and fluid exposure, allowing for resilient and flexible attachment to the body while preventing fluid penetration and facilitating heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fluid-permeable substrate is used to allow body contact and flexibility, then comfort and adaptability are improved, but fluid penetration and device damage occur
Solution Approach 1:
The substrate is functionally segmented into two distinct layers: an outer fluid-permeable layer that contacts the body and allows flexibility, and an inner fluid-impermeable dielectric layer that protects the light emitter. This segmentation allows each layer to perform its specific function without compromising the other.
Solution Approach 2:
The fluid-impermeable dielectric layer acts as an intermediary barrier between the fluid-permeable substrate and the light emitter. It mediates the conflicting requirements by allowing the substrate to remain permeable for comfort while blocking fluid from reaching the sensitive electronic components.
2Adaptability or versatility
If the gate electrode is embedded in the substrate for flexibility, then mechanical deformation tolerance is improved, but electrical current leakage between gate and channel occurs
Solution Approach 1:
The fluid-impermeable dielectric layer serves as an electrical insulator positioned between the embedded gate electrode and the channel. This dielectric intermediary prevents electrical current leakage while allowing the gate electrode to remain embedded in the flexible substrate for mechanical tolerance.
Solution Approach 2:
A thin film of fluid-impermeable dielectric material is deposited over the embedded gate electrode to provide electrical insulation. This thin film maintains the flexibility and embeddability of the gate while preventing electrical leakage to the channel.
3Measurement precision
If the light emitter is exposed to fluid for direct body contact sensing, then sensing capability is improved, but device durability and consistency deteriorate
Solution Approach 1:
The device structure is segmented so that the light emitter is isolated in a protected region by the fluid-impermeable dielectric layer, while the photodetector remains exposed through the fluid-permeable substrate. This segmentation allows the light emitter to maintain durability while the photodetector performs sensing.
Solution Approach 2:
The fluid-impermeable dielectric layer acts as a protective intermediary that prevents fluid from reaching the light emitter, thereby maintaining device durability and consistency while still allowing the photodetector to sense light after it has interacted with the user's body.
4Reliability
If multiple protective layers are added to prevent fluid penetration, then device durability is improved, but fabrication complexity and device thickness increase
Solution Approach 1:
The fluid-impermeable dielectric layer is designed to perform multiple functions simultaneously: it provides electrical insulation between the gate electrode and channel, and it acts as a fluid barrier to protect the light emitter. This multi-functionality reduces the need for separate protective layers, simplifying fabrication.
Solution Approach 2:
The electrical insulation function and fluid protection function are merged into a single fluid-impermeable dielectric layer. This consolidation reduces the total number of layers and fabrication steps compared to having separate insulation and protection layers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables reliable, long-term monitoring of health parameters like blood pressure, pulse, and oxygen saturation with improved durability and comfort, as the apparatus can conform to the body and maintain functionality despite mechanical deformation, reducing fabrication steps and enhancing device compactness.
Implementation Method 1
a layer of photosensitive material configured to vary the flow of electrical current through the channel member on exposure to light from the light emitter
Implementation Method 2
a light emitter and a photodetector formed on a single fluid-permeable substrate such that the photodetector is able to detect light emitted by the light emitter after interaction of the light with a user of the apparatus
Implementation Method 3
The layer of fluid-impermeable dielectric material may be configured to facilitate the dissipation of heat produced by the light emitter
Data Source
AI summary
An apparatus (201) comprises a light emitter (202) and a photodetector (203) formed on a single fluid-permeable substrate (206) such that the photodetector (203) is able to detect light emitted by the light emitter (202) after interaction of the light with a user of the apparatus (201). The photodetector comprises a channel member (207) which may be made from graphene, respective source and drain electrodes (208, 209), a layer of photosensitive material (210) configured to vary the flow of electrical current through the channel member (207) on exposure to light from the light emitter (202), and a gate electrode (211). The apparatus (201) further comprises a layer of fluid-impermeable dielectric material (212) configured to inhibit a flow of electrical current between the channel member (207) and the gate electrode (211) of the photodetector (203) to enable the electrical conductance of the channel member (207) to be controlled by a voltage applied to the gate electrode (211) and to inhibit exposure of the light emitter (202) to fluid which has permeated through the fluid-permeable substrate (206). The layer of fluid-impermeable dielectric material (212) allows resilient substrates made from polymeric material to be used without the risk of damage to the overlying components caused by the permeated fluid. The dual functionality of the layer of fluid-impermeable dielectric material (212) reduces the number of fabrication steps used to form the apparatus (201) and results in a thinner, more compact device.