Liquidmetal as a superior pacemaker implant
Medical devices require a level of precision, repeatability, and material properties that are found in a few manufacturing processes and materials. With a constricted set of options to choose from, engineers lose their ability to evolve products and overcome roadblocks they may be facing.
Today, most cardiac pacemakers are made with housings machined or stamped from specialized titanium alloys. Machined titanium offers the best durability, precision, and biocompatibility of a metal at high volumes. Liquidmetal Technologies’ amorphous metal molding is well suited for high-performance components like those found in implantable medical devices. To assess this statement, our team produced pacemaker shells with our amorphous metal molding process.
Liquidmetal’s big advantage: complexity with precision
As pacemaker enclosures evolve, internal support structures are becoming more common. Meeting the tolerances required for these fine features requires machining, and can quickly ramp up part cost and lead time.
Miniature structures, similar to the image below, separate internal components and save space. With Liquidmetal Technologies’ amorphous metal molding process, these features can be molded into the component in a single molding step. A product designer can expect CNC-level precision (±0.0008”) on all molded structures.
Implantable shells for pacemakers and neurostimulators on the market must fit together to form a hermetic seal, meaning the enclosure is airtight. For best results, this seal typically requires CNC-machined shells to create a tight fit before welding.
Liquidmetal’s as-molded prototype shells create a precision fit similar to CNC-machined shells and can pass a leak test when welded.
For reference, some machined titanium housings similar to those produced by Liquidmetal Technologies can cost over $80 per unit. Engineers seeking to design in an internal structure, and achieve high-level precision, should consider Liquidmetal amorphous metal molding for drastic cost reduction.
Biocompatibility: Implant safe
Pacemakers and other implantable devices come in contact with body tissues and fluids for prolonged periods of time. Ensuring the materials that they are made up of do not cause toxic or harmful effects on your body is a top priority.
Liquidmetal LM105 is has passed ISO-10993 cytotoxicity, sensitization, irritation or intracutaneous reactivity, system toxicity and hemocompatibility. Additional passed tests include implantation genotoxicity, systemic toxicity, and nickel release. In short, LM105 is safe to have outside or inside your body for your entire life.
Different metals have varying values for strength, hardness, and elasticity, but ultimately an engineer must determine which of those values are most important to their product. Liquidmetal’s difference from titanium, stainless steel, and other metals with a crystalline structure is its combination of strength and elasticity. LM105’s yield strength is roughly double titanium, and its elasticity value is unmatched by any other metal.
Liquidmetal’s strength and elasticity combination is due to its atomic structure. Elasticity is not a primary function for this application. Elasticity is appropriate because Liquidmetal returns to its original shape, with no plastic deformation, after yielding. Metals like steel and titanium permanently deform under much less strain.
An example of this could be a pacemaker enclosure inside a SCUBA diver deep underwater. The high pressure around the diver could cause the enclosure to deform or collapse, with possible life-threatening results. Liquidmetal would withstand multiples greater stress, and return to its original shape, without damaging electronics inside.
Liquidmetal Technologies’ amorphous alloys are more transparent to radio frequency (RF) signals than many materials of similar strength and hardness. Put another way; it is much more electromagnetically similar to titanium than to either copper or steel.
How a material interacts with RF electromagnetic radiation dictates its potential uses. Liquidmetal’s RF transparency makes the material suitable for emerging wireless battery charging applications.
Magnetic resonance imaging (MRI) may be the preferred tool for physicians to treat various conditions or injuries, especially for older patients. Newer pacemakers can be MRI conditional, meaning it is safe for a patient to undergo a scan under specific conditions. But in the last few years, implantable pacemaker devices have been FDA approved for full body MRI scans.
A critical attribute for a metal to be MRI safe is a lack of magnetism or ferromagnetic properties. Liquidmetal amorphous alloys are mildly diamagnetic, meaning unlike stainless steel, they cannot become magnetized over time. In short, this means Liquidmetal amorphous alloy is safe in an MRI environment.
Demand for improved image quality is increasing as MRI scanners innovate to meet physician demands. A scanner is not the only thing that impacts image quality, though, as different metals yield different image quality results. Recent testing proved Liquidmetal’s LM105 to have fewer artifacts than titanium in MRI, resulting in better imaging quality.
LM105’s ability to produce fewer image artifacts at the material level is a strong value proposition for medical professionals who utilize these tests.
Liquidmetal Technologies manufactured pacemaker housings with amorphous metal alloy LM105. Here are some things we learned:
- Liquidmetal can mold detailed internal structure features that add significant cost when using traditional machining processes.
- Liquidmetal molding meets or exceeds precision and repeatability capabilities CNC-machining offers.
- Liquidmetal yields higher quality MRI images and is MRI safe.
- Liquidmetal is suitable for wireless charging.
- Liquidmetal is biocompatible and implant safe.
To read more details about Liquidmetal’s pacemaker enclosure prototype results, download the white paper by filling out the form below.