Capacitive Skin Contact Detection for Fluid Applicators
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Solution Overview
Problem
Existing fluid applicators face challenges in reliably detecting contact with the skin, especially when fluid is present, and struggle to accurately determine the extent and location of contact, which can lead to improper activation of radiation sources and potential exposure to sensitive areas.
Innovation Solution
A contact detector device featuring a flexible outer substrate with conductive pellets and a common conductive plate, where pressure causes pellets to short-circuit, allowing for binary detection and mapping of contact extent and location, while being transparent to electromagnetic radiation and heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contact detection techniques (IR detection, ambient condition sensors, mechanical contactors) are used, then contact detection is attempted, but the detection is disturbed by the presence of fluid between the applicator surface and the skin
Solution Approach 1:
The patent replaces conventional detection techniques (IR, mechanical contactors) with a capacitive sensing system that uses electrical fields to detect contact. The applicator head includes a conductive layer that forms a capacitor with the skin, allowing detection through fluid barriers since electrical fields can penetrate the fluid without significant attenuation.
Solution Approach 2:
The system changes the detection parameter from optical/mechanical to electrical capacitance. By measuring changes in capacitance between the conductive applicator surface and the skin, the system can reliably detect contact presence and extent regardless of fluid interference, as the electrical parameter responds directly to the proximity and contact area.
2Measurement precision
If conventional contact detection is used, then contact presence is detected, but the extent and location of contact cannot be accurately determined
Solution Approach 1:
The applicator head is divided into multiple capacitive sensing zones or electrodes arranged in a matrix pattern. Each zone independently measures capacitance, allowing the system to map contact location and extent across the surface. This segmentation enables precise determination of where contact occurs and how much surface area is in contact.
Solution Approach 2:
The system provides real-time feedback by processing capacitance measurements from multiple zones to generate contact maps. This feedback mechanism allows the system to continuously update information about contact extent and location, enabling precise measurement and control of applicator-skin interaction.
3Productivity
If radiation sources are activated without reliable contact detection, then treatment can begin, but sensitive organs such as eyes or mucous membranes may be exposed to radiation
Solution Approach 1:
The capacitive sensing system provides immediate feedback about contact presence and quality before radiation activation. The system processes capacitance data to confirm proper applicator-skin contact and can detect when the applicator is near sensitive areas based on contact patterns, preventing radiation activation until safe contact conditions are verified.
Solution Approach 2:
The system performs preliminary contact verification using capacitive sensing before allowing radiation source activation. By checking contact extent and location in advance, the system ensures that the applicator is properly positioned on target tissue and not near sensitive organs, preventing harmful radiation exposure before it can occur.
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
Enables reliable detection of contact and determination of contact extent and location, controlling radiation sources effectively and providing user feedback for improved applicator usage, while being compatible with fluid applicators and radiation-emitting devices.
Implementation Method 1
pressure exerted on the flexible outer substrate causes at least one of the conductive pellets to come into contact with the common conductive plate, thereby creating at least one short-circuit signal
Data Source
AI summary
A fluid applicator including a skin contact detector device. The contact detector device includes a flexible outer substrate (S1) that defines an outer contact surface (S11), the flexible outer substrate (S1) covering a detection zone (Z) that has a plurality of conductive pellets (P1, P2, P3, P4, P5) separate from one another, the conductive pellets (P1, P2, P3, P4, P5) being arranged above a common conductive plate (D). The conductive pellets (P1, P2, P3, P4, P5), in the absence of stress, are spaced apart from the common conductive plate (D) by insulating spacers (C), so that pressure exerted on the flexible outer substrate (S1) causes at least one of the conductive pellets (P1, P2, P3, P4, P5) to come into contact with the common conductive plate (D), thereby creating at least one short-circuit signal.