Capacitive Proximity Sensing for Safe Skin-Guided Injection
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Solution Overview
Problem
Injection devices lack adequate safety features to prevent accidental medication expulsion and user injury, particularly when placed on hard surfaces or when not properly positioned on human skin.
Innovation Solution
Incorporation of a capacitive proximity sensor that detects human skin proximity and prevents needle activation unless the device is correctly positioned on a large, naked body area, combined with a mechanism for needle movement control to avoid accidental piercing or breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive proximity sensor is added to detect human skin proximity, then user safety is improved by preventing accidental medication expulsion and needle injury, but device complexity increases due to the additional sensor component and control mechanisms
Solution Approach 1:
The patent replaces mechanical safety switches or physical alignment mechanisms with a capacitive proximity sensor that uses electrical field detection to sense skin proximity. This substitution reduces mechanical complexity while maintaining safety functionality, as capacitive sensors have no moving parts and can detect skin contact through non-contact means.
Solution Approach 2:
The capacitive sensor acts as an intermediary between the physical act of placing the device on skin and the electronic control system. It translates physical proximity into an electrical signal that triggers safety interlocks, mediating the interaction between user action and device response without requiring direct mechanical contact switches.
2Measurement precision
If the capacitive sensor is set to detect only large naked body areas, then accuracy of skin detection is improved to distinguish from small objects like fingers, but measurement precision requirements increase to reliably differentiate between valid and invalid contact surfaces
Solution Approach 1:
The patent moves from simple binary detection (contact/no contact) to multi-dimensional characterization by measuring both the magnitude and spatial distribution of capacitive coupling across multiple sensor electrodes. This allows the system to distinguish skin from other materials based on the pattern and extent of capacitive interaction, not just presence/absence.
Solution Approach 2:
The capacitive sensor system serves multiple functions simultaneously: it detects skin proximity, verifies proper device placement on a valid body surface, and provides feedback for user guidance. This multi-functionality consolidates what would otherwise require separate detection systems into a single integrated solution.
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
Enhances user safety by ensuring medication is only injected when the device is correctly placed on skin, reducing risks of accidental expulsion and needle injury during handling.
Implementation Method 1
a capacitive proximity sensor for detecting proximity or contact of human skin to/with said surface
Implementation Method 2
The capacitive sensor is preferably so set that a mere contact of a finger on said surface is not detected and/or that materials such as dry clothes, dry cotton, dry leather, wood, plastic, metal, ceramic, glass are not detected
Data Source
AI summary
An injection device for injecting medication to a patient, comprising a surface (5) having a through hole (3) for passage of a needle, is characterised by further comprising a capacitive proximity sensor (12, 13, 30) for detecting proximity or contact of human skin to/with said surface (5).