Pen Drug Injector Absolute Angular Dose Encoder
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Solution Overview
Problem
Current pen-type drug delivery devices lack an efficient mechanism for accurately determining the absolute rotational position of a cylindrical member, which is crucial for precise dosing of insulin or other medicinal products, especially for users who need to administer doses between 1 and 80 International Units without formal medical training.
Innovation Solution
A drug delivery device featuring a cylindrical member with a single track encoding system, comprising first and second track segments that induce distinct responses in sensors, allowing for the determination of the rotational position using a processor that analyzes signals from electrical or optical sensors, enabling precise dose setting and dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single track encoder system is used to determine rotational position, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The single track is segmented into multiple distinct track segments (first track segments and second track segments) with different electrical resistance values. These segments are arranged in specific patterns along the track, allowing the sensor to detect unique combinations of segments at different rotational positions. This segmentation enables precise rotational position determination while maintaining a simple single-track structure.
Solution Approach 2:
Different portions of the single track are given different local properties through the variation of electrical resistance values across different track segments. Each track segment has a specific resistance value that contributes to a unique electrical signature for its corresponding rotational position. This local quality variation allows the system to encode multiple position states within a single continuous track structure.
2Measurement precision
If multiple sensors are used to detect track segments, then measurement precision improves, but device complexity increases
Solution Approach 1:
The single track with varied resistance segments serves multiple functions simultaneously: it acts as both the encoding structure and the sensing element. The track segments are electrically coupled to form a continuous conductive path that can be interrogated by the sensor to determine rotational position. This multi-functional design eliminates the need for separate encoding tracks and sensor arrays, reducing overall system complexity while maintaining measurement precision.
3Manufacturing precision
If electrical resistance variations are used to encode position information, then manufacturing precision requirements are reduced, but reliability of signal detection may worsen
Solution Approach 1:
The sensor continuously monitors the electrical resistance values of the track segments and provides feedback to the processor. The processor analyzes the pattern of resistance values to determine the current rotational position. This feedback mechanism allows the system to compensate for manufacturing variations and ensures reliable position detection even when resistance values deviate slightly from nominal specifications.
Solution Approach 2:
The system utilizes changes in electrical resistance as the primary encoding parameter. By varying the resistance values of different track segments and analyzing the pattern of resistance changes as the cylindrical member rotates, the system can reliably determine rotational position. This parameter-based approach is more tolerant of manufacturing variations than dimension-based encoding methods.
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 accurate and precise determination of the rotational position of the cylindrical member, allowing for reliable and user-friendly administration of specific drug doses, enhancing the management of conditions like diabetes by ensuring precise glycemic control.
Implementation Method 1
The plurality of sensors may each comprise an electrical contact, and the first and second track segments may respectively have lower and higher values of electrical resistance
Data Source
AI summary
A drug delivery device comprising: a housing; a cylindrical member rotatably supported within the housing; and a plurality of sensors; wherein: the outer surface of the cylindrical member is provided with a single track, the track forming an encoder and having a plurality of first track segments and a plurality of second track segments arranged along the length of the track which are respectively capable of inducing first and second responses in the sensors; and in each rotational position of the cylindrical member relative to the housing at least one different first track segment is capable of inducing a first response in at least one said sensor, thereby enabling the rotational position of the cylindrical member relative to the housing to be determined.