Dual Ratchet Drive Sensing for Low-Power Insulin Delivery
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Solution Overview
Problem
Existing on-body drug delivery systems face challenges in power efficiency due to the need for minimizing the energization time of shape memory alloy (SMA) wires in drive systems, particularly with ratchet wheels, which results in inefficiencies and potential missed insulin deliveries.
Innovation Solution
A dual wheel drive mechanism with sensor contacts is introduced, allowing precise timing of the drive arm stroke by detecting tooth clearance signals, ensuring optimal energy usage and complete stroke completion, thereby enhancing power efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive arm is allowed to overtravel to clear the ratchet wheel tooth, then the drive arm ensures complete stroke completion, but the SMA wire remains energized longer causing power loss
Solution Approach 1:
A sensor detects when the non-driving drive arm clears the ratchet wheel tooth and provides feedback to the control circuitry. The control circuitry uses this feedback signal to immediately stop energizing the SMA wire, preventing unnecessary continued energization while ensuring the drive arm has completed its stroke.
Solution Approach 2:
The patent replaces the traditional mechanical tolerance-based overtravel approach with an electronic sensing and control system. Instead of relying on mechanical clearance tolerances, the system uses a sensor to detect tooth clearance and electronically controls the SMA wire energization timing.
2Use of energy by moving object
If tight tolerances are used to minimize drive arm overtravel, then power efficiency is improved, but the risk of incomplete stroke increases
Solution Approach 1:
The sensor provides real-time feedback on the actual position of the drive arm relative to the ratchet wheel tooth. This feedback allows the control system to verify that the drive arm has fully cleared the tooth before stopping energization, ensuring reliable stroke completion even with tight tolerances.
Solution Approach 2:
The patent substitutes mechanical tolerance design with electronic detection and control. The sensor-based detection system provides precise measurement of drive arm position, replacing the need for conservative mechanical tolerances and enabling tighter tolerances to be used safely.
3Device complexity
If a single ratchet wheel is used, then device complexity is reduced, but power efficiency opportunities are limited
Solution Approach 1:
The patent divides the drive system into two separate ratchet wheels, each with its own drive arm and sensor. This segmentation allows independent control and sensing of each drive cycle, enabling more precise energy management. The dual-wheel configuration provides two opportunities for power efficiency improvements per full delivery cycle.
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 dual wheel drive mechanism achieves energy savings and ensures accurate insulin delivery by optimizing the stroke length of the drive arm, reducing energy waste and preventing missed cycles, thus improving the overall power efficiency and effectiveness of the drug delivery system.
Implementation Method 1
as explained in further detail below, substantial power savings may be achieved from minimizing the amount of time elements of the drive system have to energized. Drive systems that utilize shape memory alloy (SMA) wires would benefit by shortening the time the SMA wire is energized.
Data Source
AI summary
Disclosed are techniques for managing the application of a force by a drive mechanism in a drug delivery device as well as devices for implementing the disclosed techniques. One or more driving arms may be operable to drive a respective ratchet wheel and one or more sensor contacts may be positioned to determine when a respective driving arm is to be controlled to no longer drive the respective ratchet wheel thereby saving electrical power. The disclosed techniques and devices may be incorporated in a drug delivery device, such as those carried by a person or affixed to the skin of a person.