Subcutaneous Tissue Pressure Profiling for Leak-Safe Drug Delivery
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Solution Overview
Problem
Wearable medical devices face issues with fluid leaks and system failures due to increased pressure in the fluid line caused by variable tissue resistance and absorption rates, leading to incomplete drug delivery and potential contamination.
Innovation Solution
A method and device that measure tissue properties by applying pressure profiles through a fluid line, calculating parameters like fluidic resistance and permeability, and adjusting the delivery profile accordingly to optimize drug absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed delivery flow rate is used, then the device operation is simple, but tissue resistance variation causes pressure buildup and fluid leaks
Solution Approach 1:
The system transitions from fixed flow rate to dynamic flow rate adjustment. The controller continuously monitors pressure sensor feedback and adjusts the pump motor speed to maintain optimal delivery parameters, preventing pressure buildup while adapting to tissue resistance variations.
Solution Approach 2:
The system implements closed-loop feedback control where the pressure sensor monitors fluid pressure in real-time, and the controller adjusts the pump motor speed based on this feedback. This ensures the delivery flow rate adapts to tissue conditions, preventing leaks while maintaining reliable drug delivery.
2Productivity
If high delivery flow rate is used, then drug delivery speed increases, but tissue resistance causes pressure buildup compromising fluid line integrity
Solution Approach 1:
The system dynamically adjusts the delivery flow rate based on real-time pressure feedback. When tissue resistance increases and pressure approaches threshold levels, the controller automatically reduces the pump motor speed to maintain fluid line integrity while still delivering the full dose.
Solution Approach 2:
The system changes the operational parameters (pump motor speed, delivery flow rate) based on measured tissue properties. By adjusting these parameters dynamically, the system maintains optimal delivery speed while preventing pressure buildup that would compromise fluid line integrity.
3Reliability
If pressure threshold is increased to prevent leaks, then fluid line integrity improves, but delivery completion may be compromised
Solution Approach 1:
The pressure sensor provides continuous feedback to the controller, which adjusts the pump motor speed in real-time to maintain pressure below the threshold. This ensures fluid line integrity is preserved while still delivering the complete dose through adaptive flow rate control.
Solution Approach 2:
The system dynamically balances delivery speed and pressure control by continuously adjusting pump motor speed based on tissue conditions. This prevents pressure from reaching dangerous thresholds while maintaining complete delivery of the pharmaceutical composition.
4Device complexity
If tissue properties are not measured, then the device structure remains simple, but delivery optimization is limited
Solution Approach 1:
The system performs self-characterization of the tissue by measuring pressure response during and after injection. This self-measurement capability provides tissue property data without requiring external measurement devices or complex additional hardware, enabling delivery optimization based on actual tissue conditions.
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 precise drug delivery by identifying suitable injection sites and adjusting flow rates based on tissue properties, preventing leaks and ensuring complete drug delivery while maintaining device integrity.
Implementation Method 1
measuring a pressure value or flow rate value over time in response to the applied pressure profile or applied flow profile
Implementation Method 2
applying a pressure profile or flow profile to the subcutaneous tissue via the fluid line
Implementation Method 3
A negative pressure profile is applied to the subcutaneous tissue, with the negative pressure profile lower than atmospheric pressure
Implementation Method 4
using an insertion mechanism to insert a needle and catheter into the subcutaneous tissue
Data Source
AI summary
A method of measuring tissue properties using a fluid line in fluid communication with a subcutaneous tissue includes applying a pressure profile or flow profile to the subcutaneous tissue via the fluid line, with the fluid line isolated from atmospheric pressure, measuring a pressure value or flow rate value over time in response to the applied pressure profile or applied flow profile, and calculating, using at least one processor, at least one of the following: time constant of pressure decay; fluidic resistance of tissue; permeability of tissue; mechanical compliance of tissue; osmotic pressure of interstitial fluid of tissue; capillary pressure in subcutaneous tissue; and ionic strength of interstitial fluid.