Acoustic Fluid Volume Sensing for Wearable Drug Dispensing
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Solution Overview
Problem
Existing portable devices for controlled release of therapeutics face challenges such as malfunction rates, size, weight, and cost issues, and require a wearable solution for automatic delivery of drugs over time, especially for medications with poor absorption or requiring frequent administration.
Innovation Solution
A wearable fluid delivery system with a pumping chamber and force application assembly that restricts retrograde flow, uses shape-memory actuators for pressurization, and includes a passive valve for unidirectional flow, allowing for precise control and measurement of fluid dispensation through a tortuous conduit, enabling basal and bolus modes of operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If portable devices are designed for controlled release of therapeutics, then automatic delivery capability is achieved, but device size and weight increase
Solution Approach 1:
The device is divided into separate components: a disposable cartridge containing the therapeutic reservoir and flow control elements, and a reusable pump unit. This segmentation allows the heavy automated pumping mechanism to be separated from the disposable portion, reducing the weight burden on users while maintaining automatic delivery capability.
Solution Approach 2:
The inlet valve is integrated within the pump chamber structure, and the flow control assembly is nested within the cartridge. This nested arrangement minimizes overall device volume and weight by eliminating redundant structural elements and optimizing space utilization.
2Extent of automation
If portable devices are designed for controlled release of therapeutics, then automatic delivery capability is achieved, but device cost increases
Solution Approach 1:
By separating the device into disposable and reusable components, manufacturing costs are reduced through simplified production processes for each part. The disposable cartridge can be manufactured using cost-effective techniques like injection molding, while the reusable pump unit is manufactured once and refilled, reducing overall system cost.
Solution Approach 2:
The cartridge is designed as a disposable component that can be manufactured at low cost and discarded after use. This eliminates the need for expensive sterilization and maintenance procedures, reducing the overall cost of the automated delivery system while maintaining reliability.
3Measurement precision
If flow control mechanisms are added to control retrograde flow, then delivery precision is improved, but device complexity increases
Solution Approach 1:
The inlet valve and pump chamber are combined into an integrated assembly where the valve is positioned within the pump chamber structure. This merging reduces the number of separate components and connections, simplifying the overall device while maintaining precise flow control capability.
Solution Approach 2:
The passive check valve automatically prevents retrograde flow without requiring external control mechanisms. The valve self-actuates based on pressure differentials during pumping cycles, eliminating the need for additional motors, sensors, or control electronics, thereby reducing device complexity while ensuring precise unidirectional flow.
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 reliable, efficient, and controlled delivery of therapeutic fluids, reducing malfunction rates and improving patient compliance by automating drug administration while minimizing device size and weight.
Implementation Method 1
using a shape-memory actuator. Also optionally, using the shape-memory actuator includes inducing a phase change in a shape memory wire to transmit a force around a pulley to the force application assembly.
Data Source
AI summary
An apparatus for determining the volume of fluid dispensed. The apparatus has an acoustic volume sensor that acoustically excites a reference volume and a measurement chamber with a loudspeaker and measures the acoustic response with microphones acoustically coupled to the reference and the measurement chamber. The loudspeaker and sensing microphones are connected to the measurement chamber by separate ports. A detachable dispensing chamber is coupled to the acoustic volume sensor. The volume of the fluid dispensed is determined by a processor based on the acoustic response of the microphones to acoustic excitement by the loudspeaker.