Additively Manufactured Nitinol Implants With Tuned Shape Memory
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Solution Overview
Problem
Nickel-titanium alloys, also known as Nitinol, are difficult to manufacture using conventional methods, leading to material wastage and time consumption, and existing methods do not effectively exploit their superelastic and shape memory properties for implantable objects.
Innovation Solution
A method involving additive manufacturing is used to fabricate implantable objects by melting a powder comprising nickel and titanium, iteratively forming stacked metallic layers, and adjusting energy parameters to achieve a transformation temperature suitable for superelastic and shape memory effects, with support structures that can be removed through pickling or electro-polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional machining methods are used to manufacture Ni-Ti alloys, then the material can be processed, but material wastage increases and manufacturing time is consumed
Solution Approach 1:
The patent changes the manufacturing approach from subtractive (machining) to additive (layer-by-layer fabrication), fundamentally altering the process parameters to eliminate material removal and associated wastage
Solution Approach 2:
The additive manufacturing process allows for localized material deposition only where needed, creating complex geometries without the material wastage inherent in conventional machining methods
2Ease of manufacture
If conventional machining methods are used to manufacture Ni-Ti alloys, then the material can be processed, but manufacturing time increases
Solution Approach 1:
The patent transitions from sequential material removal (machining) to parallel layer-by-layer construction, fundamentally changing the manufacturing parameters to reduce overall production time
Solution Approach 2:
The support structures are designed and integrated into the manufacturing process beforehand, allowing for simultaneous fabrication of both the implant and support structures, thereby reducing total manufacturing time
3Reliability
If conventional manufacturing methods are used, then implantable objects can be produced, but superelastic and shape memory properties are not effectively exploited
Solution Approach 1:
The patent controls energy source parameters (power, speed, hatch spacing) to achieve specific energy densities that control transformation temperature, enabling the exploitation of superelastic and shape memory properties
Solution Approach 2:
The patent adds a thermal dimension to the manufacturing process by controlling transformation temperature through energy source parameters, enabling temperature-dependent functional properties in the implantable object
4Reliability
If energy source parameters are adjusted to achieve desired transformation temperature, then superelastic and shape memory effects are enabled, but manufacturing process complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges (energy density 50-90 kJ/mm³, laser power 55-200 W, scan speeds 105-1245 mm/s, hatch spacing 30-100 microns) that provide controllable transformation temperature while maintaining manufacturing feasibility
Solution Approach 2:
The patent uses support structures that are intentionally over-formed during manufacturing and then partially removed through pickling or electro-polishing, simplifying the overall manufacturing process by enabling single-step fabrication of complex geometries
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 method enables the production of implantable objects that can expand or contract based on temperature changes, reducing material waste and allowing for precise, patient-specific designs with enhanced mechanical properties.
Implementation Method 1
melting a powder comprising at least nickel and titanium with an energy source
Implementation Method 2
Nickel-titanium alloys, also known as Nitinol, may exhibit a shape memory effect and superelastic behaviour
Implementation Method 3
Superelasticity (also referred to as pseudoelasticity) is reversible elastic characteristic of a material
Implementation Method 4
The support structures may be at least partially removed by pickling the implantable object
Implementation Method 5
The support structures may be at least partially removed by electro-polishing the implantable object
Data Source
AI summary
An implantable object (1000′) and a method (100) of fabricating an implantable object is disclosed. The method (100) comprises melting a powder (210) comprising at least nickel and titanium with an energy source (220) and iteratively forming a plurality of stacked metallic layers (330) from the melted powder using an additive manufacturing technique. The implantable object is biased to expand from a first configuration (501) to a second configuration (502) when at or above a transformation temperature.