Polylactic Acid Stent Laser Patterning
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Solution Overview
Problem
Existing polymeric stents made from biodegradable polymers like polylactic acid face challenges with mechanical strength and degradation due to sensitivity to heat, moisture, and light, and the processing methods using long pulse lasers can cause thermal injuries and rapid molecular weight decrease.
Innovation Solution
The method involves using a second harmonic generator laser with a wavelength range of 940 nm to 1552 nm to form patterns on polylactic acid tubes, which minimizes thermal injury and degradation, maintaining a low variation in polydispersity index and average molecular weight, and applying a composition to prevent restenosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long pulse lasers are used to form patterns on polymeric stents, then processing speed is improved, but thermal injury increases and molecular weight decreases rapidly
Solution Approach 1:
The patent changes the laser pulse duration parameter from long pulse to short pulse regime, and adjusts the wavelength to specific ranges (500-550nm or 1000-1100nm). This parameter transformation enables effective pattern formation while minimizing thermal diffusion and molecular weight degradation, resolving the contradiction between processing efficiency and thermal damage
Solution Approach 2:
The patent employs periodic pulsed laser irradiation with optimized duty cycles and pulse intervals. This periodic action allows heat dissipation between pulses, preventing cumulative thermal injury while maintaining effective pattern formation, thus resolving the contradiction between processing speed and thermal damage
2Productivity
If long pulse lasers are used to form patterns on polymeric stents, then processing speed is improved, but molecular weight decreases rapidly
Solution Approach 1:
The patent transforms the laser processing parameters by switching to short pulse duration and specific wavelength ranges that resonate with polymer bond frequencies. This causes selective bond breaking and pattern formation without excessive heating, thereby maintaining molecular weight stability while achieving high processing speed
Solution Approach 2:
The patent replaces thermal-mechanical processing with photochemical processing using short pulse lasers. The laser energy directly breaks chemical bonds through photolysis rather than through thermal heating, substituting a mechanical/thermal process with an optical-chemical process that preserves molecular weight
3Manufacturing precision
If conventional laser processing is used on polymeric stents, then pattern formation is achieved, but mechanical strength decreases due to thermal injury
Solution Approach 1:
The patent optimizes laser parameters including wavelength (500-550nm or 1000-1100nm), pulse duration (short pulse), and energy density to achieve precise pattern formation. These parameter changes enable clean cutting and patterning without the thermal degradation that compromises mechanical strength
Solution Approach 2:
The patent converts the laser's thermal effect from a harmful factor to a beneficial one by using controlled short pulse heating that melts and fuses polymer chains at the pattern edges, creating heat-affected zones that actually strengthen the structure around the patterns while maintaining overall mechanical integrity
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
This approach enhances the mechanical strength and reduces biodegradation of polymeric stents while maintaining the molecular weight, ensuring the stents have superior properties and can be effectively expanded and implanted without significant thermal injury.
Implementation Method 1
forming a pattern on a polylactic acid tube with a second harmonic generator laser in which a wavelength ranging from about 940 nm to 1552 nm or less is converted
Data Source
AI summary
Methods of manufacturing polymeric stents by forming a pattern on a polylactic acid tube using a second harmonic generator laser and polylactic acid polymeric stents having a pattern formed using a second harmonic generator laser.