Biliary Stent with Phase-Transforming Valve for Sphincter Mimicry
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Solution Overview
Problem
Conventional biliary stents fail to replicate the natural motor functionality of the Sphincter of Oddi, leading to persistent bacterial infection and inadequate bile flow in patients with bile duct obstructions, as they permanently open the Sphincter of Oddi, allowing bacteria to enter the biliary tree and causing infections.
Innovation Solution
A stent comprising a first region with a self-expanding, phase-transforming cellular material that mimics the mechanical and geometric changes of the Sphincter of Oddi, allowing for controlled opening and closing in response to energy imbalances, pressure changes, and cholecystokinin concentration, and a second region with a one-way valve to prevent backflow, emulating the natural function of the ampulla of Vater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional biliary stent is placed to maintain bile flow, then the biliary obstruction is relieved, but the Sphincter of Oddi remains permanently open allowing bacterial infection
Solution Approach 1:
The stent incorporates a dynamic valve mechanism that can open and close in response to pressure changes and cholecystokinin concentration, replicating the natural Sphincter of Oddi function. The valve transitions between open and closed states based on physiological conditions, allowing bile flow when needed while preventing bacterial entry during closure.
Solution Approach 2:
The valve mechanism responds to changes in physical parameters (pressure differential) and chemical parameters (cholecystokinin concentration) to control its state. When pressure in the common bile duct exceeds duodenal pressure or CCK levels are high, the valve opens to allow bile flow; otherwise, it closes to prevent infection.
2Ease of operation
If the Sphincter of Oddi is kept open to facilitate bile flow, then bile drainage is improved, but bacteria from the duodenum can enter the biliary tree causing infection
Solution Approach 1:
The valve operates periodically, opening during digestion when cholecystokinin is released and closing during non-digestive periods. This periodic operation mimics natural sphincter function, allowing bile to reach the duodenum when needed while maintaining a closed barrier against bacterial contamination during other times.
Solution Approach 2:
The valve mechanism incorporates feedback from pressure sensors and chemical sensors (detecting cholecystokinin) to control its opening and closing. The system continuously monitors physiological conditions and adjusts the valve state accordingly, opening when bile flow is needed and closing when infection risk is present.
3Reliability
If a stent is inserted into the common bile duct, then biliary obstruction is relieved, but the natural motor functionality of the Sphincter of Oddi is lost
Solution Approach 1:
The stent design combines multiple functions: maintaining biliary patency through the stent structure and replicating sphincter motor functionality through the integrated valve mechanism. The valve provides both a mechanical barrier function and a flow control function, making the device universally capable of both obstruction relief and sphincter replacement.
Solution Approach 2:
The valve mechanism is designed to copy the natural Sphincter of Oddi's motor functionality and response characteristics. It replicates the sphincter's opening and closing behavior in response to the same physiological stimuli (pressure changes and cholecystokinin), effectively creating an artificial replacement that mimics natural function.
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 stent effectively maintains bile flow while preventing bacterial infection by replicating the natural function of the Sphincter of Oddi, allowing for the administration of cancer treatments and reducing the risk of jaundice, thereby improving patient outcomes.
Implementation Method 1
The second region can be comprised of one or more phase transforming cellular materials (PXCM) configured to move the outlet between an open configuration and a closed configuration in response to a change in one or more of an energy imbalance in the PXCM, a change in pressure through an interior of the second region, and a change in a local concentration of cholecystokinin (CCK).
Data Source
AI summary
Stents comprising a first region and a second region are provided, where at least the second region comprises one or more phase transforming cellular materials configured to move the outlet between an open configuration and a closed configuration in response to certain triggers. Such stents can also comprise one or more analog for a shape memory alloy (ASMA) unit cells on an inner surface of the first region such that, in response to resistive forces, the ASMA unit cells exert controllable motion to clear the stent. Methods of treatment of cancer, jaundice, and other diseases are also provided.