Magnetic Dose Wheel Sensing for Accurate Injector Dose Tracking
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Solution Overview
Problem
Existing injectable-drug delivery devices face challenges with complex mechanical solutions that overcomplicate dosage control, leading to user errors, lost doses, and non-compliance, requiring a system that can accurately measure doses without axial displacement calculations and minimal modification to the device.
Innovation Solution
A dose control system using a removably attachable housing with magnetic field measurement means in a displaced axial relationship to the drug delivery device's longitudinal axis, an integrated control unit to process magnetic field data, and magnetometers to calculate a normalized vector and corrected offset values, enabling accurate dose setting without axial alignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical means are used to prevent excessive dose injections, then dosage control is improved, but device complexity increases and user operation becomes complicated
Solution Approach 1:
The patent replaces complex mechanical dosage control mechanisms with a magnetic field-based detection system. A magnet is attached to the dose setting wheel, and magnetic field measurement means detect the magnet's position to determine the selected dose. This substitution eliminates the need for complex mechanical interlocks and counters, significantly reducing device complexity while maintaining reliable dosage control.
Solution Approach 2:
The magnetic field measurement system serves multiple functions: it detects the selected dose, monitors injection progress, and can track administered versus remaining doses. This multi-functionality replaces what would traditionally require separate mechanical systems for each function, reducing overall device complexity while improving reliability.
2Device complexity
If magnetic field measurement means are positioned non-axially, then device complexity is reduced, but measurement precision deteriorates due to alignment issues
Solution Approach 1:
The patent changes the measurement parameters by using multiple magnetic field measurement means (sensors) positioned at different locations. Instead of relying on precise axial alignment of a single sensor, the system uses the combined output of multiple sensors to calculate the magnet's angular position. This parameter change approach makes the system robust to misalignment while maintaining measurement precision.
Solution Approach 2:
The patent introduces a computational intermediary (the control system) that processes magnetic field data from multiple sensors. This intermediary calculates the normalized vector and corrects for offset values, effectively mediating between the non-ideal sensor positions and the required measurement precision. The computational processing compensates for the non-axial positioning that would otherwise degrade measurement accuracy.
3Measurement precision
If multiple magnetic field measurement means are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple magnetic field measurement means into a unified computational model. The control system combines the outputs of multiple sensors to calculate a single normalized vector representing the magnet's position. This merging approach allows the system to use multiple sensors for improved precision while presenting a simplified interface and control logic, effectively managing device complexity.
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
The system provides accurate dose calculation and user-friendly operation, unaffected by non-axial alignment of magnetic field measurement means, allowing for use with various drug delivery devices and minimizing device modification, ensuring precise dosage tracking and user compliance.
Implementation Method 1
at least a first and a second magnetic field measurement means configured to measure the magnetic field produced by the substantially disk-shaped diametral single-dipole magnet
Data Source
AI summary
The invention relates to a dose control system configured for an injectable drug delivery device. The device comprises a disk-shaped diametral single-dipole magnet (9) attachable to a rotatable dose wheel, a housing removably attachable to the proximal extremity of the drug delivery body and comprising at least a first and a second magnetic field measurement means (8). An integrated control unit (2) is connected to the magnetic field measurement means and is configured to process information received therefrom. The magnetic field measurement means are located in the housing in a displaced axial relationship relative to the longitudinal axis of the drug delivery body and the magnet. The magnet is configured to co-rotate with the dose setting wheel and the integrated control unit is configured to provide a normalized vector with regard to the displaced axial relationship of the magnetic field measurement means, said normalized vector being derived from the measured magnetic field generated by the rotation of the magnet and measured by the magnetic field measurement means. A dose setting is calculated from said normalized vector.