Helical Track Dose Encoder for Pen-Type Drug Injection Devices
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Solution Overview
Problem
Pen-type drug delivery devices for self-administration of insulin lack accurate dosing mechanisms that can differentiate between dialing and dispensing modes, leading to potential errors in insulin delivery for diabetes management.
Innovation Solution
A drug delivery device with a helical track that induces different responses in sensors based on its position, allowing for accurate determination of the drug dose delivered and distinguishing between dialing and dispensing modes, utilizing a processor to interpret these responses and determine the operational mode through a lookup table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple dose setting mechanism is used, then device complexity is reduced, but measurement precision of dose delivery cannot be differentiated between dialing and dispensing modes
Solution Approach 1:
The helical track is segmented into multiple track segments of different types (first type and second type) arranged at different axial positions. Each segment type provides distinct sensor responses, enabling the system to differentiate between dialing and dispensing modes. This segmentation allows precise dose delivery differentiation without requiring a completely complex encoding mechanism.
Solution Approach 2:
The patent introduces an axial dimension to the encoding mechanism by arranging track segments at different axial positions along the helical track. This adds a spatial dimension beyond simple rotational encoding, allowing the sensors to detect both dialing and dispensing modes through the axial position differences of track segments, thereby improving measurement precision while managing device complexity.
2Measurement precision
If sensors continuously monitor the helical track, then measurement precision of dose amount is improved, but use of energy increases
Solution Approach 1:
The system employs periodic action by activating sensors only during specific phases of the dosing operation. During dialing mode, sensors monitor the helical track to determine the dialled dose amount. During dispensing mode, the system can reduce or stop sensor monitoring since the dose amount is already determined by the mechanical dispensing mechanism. This periodic sensor activation maintains measurement precision when needed while significantly reducing overall energy consumption.
Solution Approach 2:
The helical track itself provides the encoding information through its geometric design with different track segment types positioned at different axial locations. The track structure inherently carries the information needed for dose determination without requiring additional active sensing components or continuous power-consuming electronics, allowing the system to achieve precise measurement with minimal energy input.
3Adaptability or versatility
If multiple track segments of different types are used, then adaptability of mode differentiation is improved, but device complexity increases
Solution Approach 1:
Different portions of the helical track have different local qualities - specifically, track segments of the first type are positioned at certain axial locations while track segments of the second type are positioned at other axial locations. This variation in local quality (track segment type) at different positions enables the system to differentiate between dialing and dispensing modes. The local quality differentiation is achieved through relatively simple geometric variations in the track structure rather than complex mechanisms.
Data Source
AI summary
A drug delivery device comprising: a housing; a plurality of sensors; and a cylindrical member supported within the housing, an outer surface of said cylindrical member being provided with a helical track, the helical track comprising track segments of a first type and track segments of a second type, the first and second types of track segments being respectively capable of inducing first and second responses in the sensors; wherein: the helical track has a width; the helical track includes across the width of the helical track at least one track segment of the first type and at least one track segment of the second type at plural positions along a length of the helical track; the device is configured such that during a first phase of a drug delivery operation the helical track is moved axially, without rotation, relative to the plurality of sensors between a first position and a second position, and during a second phase of the drug delivery operation the track is moved helically relative to the plurality of sensors from the second position; and responses induced in the plurality of sensors by the track segments of the helical track are different in the first position compared to responses induced in the plurality of sensors by the helical track in the second position.