Medical device manufacturing’s worldwide revenue exceeds $407 billion and projections are for continued, strong growth fueled by an aging population and response to COVID-19.
3D printed NP test swabs; personal protective equipment
In partnership with Formlabs, USF Health, Tampa General Hospital, and Norwell Health, ROE Laboratories has been granted a production license for 3D-printed nasopharyngeal (NP) test swabs. The current product capacity is more than 21,000 test swabs per day. The swabs are being printed from biocompatible, autoclavable, and FDA cleared surgical guide resin.
A clinical trial using EnvisionTEC 3D-printed nasopharyngeal (NP) swabs for COVID-19 testing will help address the shortage of the test devices. One advantage of the EnvisionTEC NP swab is it performed the same, mechanically, after being sterilized by steam at 270°F at 27Pa in an autoclave. E-Guide Soft, a biomedically safe 3D printing material from EnvisionTEC, and EnvisionTEC’s swab design have both passed all required tests.
EnvisionTEC worked with Beth Israel Deaconess Medical Center (BIDMC) to develop a swab design and material to be printed on its Envision One cDLM 3D printer, which can produce up to 2,400 swabs in 24 hours.
EnvisionTEC, and a growing number of their Envision One cDLM customers who have also registered with the FDA, have the mass production capabilities to produce up to one million swabs per day.
Questions With Eric Schwarzenbach
Advertorial - Ask the Expert
Rollomatic’s US president discusses grinding, software, and step-loaders used to produce orthopedics and medical parts.
1. How can you efficiently grind surgical saw blades?
Oscillating, sagittal, and reciprocating saw blades often have tooth-set blades with teeth bent right and left for larger clearances and more aggressive cuts. Rollomatic’s GrindSmart 630XW grinder and other machines with 6-axis kinematics can grind various types of saw blades. A fixture holds blades horizontally, allowing automatic loading/unloading. The 6th axis generates different tooth rake angles. A diamond-style tooth pattern also requires a 6th axis inclination.
To speed production, a multi-profile wheel can grind several teeth simultaneously, and a wheel changer can engage multiple wheels to grind channels between teeth.
2. How can software support orthopedic tool grinding?
Rollomatic’s VirtualGrindPro tool design software can make short runs more attractive, inserting lean manufacturing principles into CNC tool grinding. Workflow and workplace organization, process standardization, and waste reduction are now properly addressed in surgical tool manufacturing, standardizing surgical tool production rather than looking at it as an art.
3. What other kinds of grinding are common in medical manufacturing?
Centerless grinding rests the workpiece on a knife-edge support, rotates it through contact with a regulating or feed wheel, and removes material with a grinding wheel. This method grinds long, thin parts without steady rests and lessens taper problems.
Fixation pins, K-wires, trocars, rods, and tubing typically require a Swiss-style lathe and a centerless grinder.
Pinch-and-peel grinding offers the highest concentricity. Rough and finish grinding occur in one pass, eliminating a step to reduce cycle time. Two different grinding wheels run on separate spindles positioned on independently-controlled CNC linear slides.
4. What is a step loader?
The loading side of a magazine feeder is a gravity-fed V-type storage section with a separator at the bottom. Parts are laid horizontally into a tray, and a loader arm transports parts into the machine at a certain height above the V-type storage tray. A step-up system in a diagonal angle transports blanks to that height, carrying them up in steps, one blank per step, depositing the piece to be loaded into a pick-up tray. The storage section keeps remaining blanks in queue until needed. Step width can be adjusted to suit the blank’s diameter.
5. How does a tool grinder handle quick disconnect when grinding cutting geometry?
Quick disconnect features on shank-ends of orthopedic cutting instruments provide a fast, easy connection/disconnection to the motor-driven handpiece. When required to clear a shoulder and grip on a smaller diameter, shank ends are usually larger than the actual tip or cutting edge. Rollomatic offers over-grip clamping systems that can accommodate such parts.
A less common part, an olive wire with a bulge in the part’s center, uses a special collet that allows the automatic loader to insert the bulge into the collet from the side instead of the front. After side-entry, the part is pushed further into the collet and the bulge gets swallowed in the back of the system.
More medical applications demand users skilled in liquid silicone rubber (LSR) molding, according to Reports & Data, which predicts a 7.3% compound annual growth rate (CAGR) to a $3.8 billion global industry by 2026. Nigel Flowers, managing director of Sumitomo (SHI) Demag UK explores the recent popularity of LSR and how molders can adapt to this lucrative market.
Today’s Medical Developments (TMD): What makes LSR so different to other molding materials?
Nigel Flowers (NF): LSR is fairly unique in that it remains flexible and elastic down to -50°C, yet retains its properties up to 200°C. This is why LSR is starting to be used more extensively in encapsulated electronic components, cables etc., where insulation is required for user safety. Additionally, LSR stands up well to ultraviolet (UV) and chemical exposure.
TMD: How can LSR be used in medical applications?
NF: For many years LSR has been used in the baby care market, for pacifiers and bottles. Now, LSR is being used to create implantable devices, wearables to track blood pressure or heart rates, as well as smaller medical devices with more intricate designs and micro parts.
One key characteristic of LSR is its biocompatibility and the fact it is bacteria resistant, hydrophobic, odorless, and can withstand repeatable sterilization at high heat. All of which lend the material well to healthcare applications.
TMD: Can you overmold with LSR?
NF: Overmolding works extremely well for several devices that require special aesthetics, for example a comfortable soft-touch grip on tool handles or disposable razors. The ability to add adhesion to the material assists with this and helps reduce the number of production steps for a molder.
Critically, LSR can be molded onto both bondable and non-bondable materials, including metal, glass, and ceramics. This assists with manufacturing efficiency, helping reduce the number of individual components and consequently reduce assembly costs.
TMD: How does LSR processing vary from other materials?
NF: The low viscosity of the material requires high precision processing. Compared to polymer granules, LSR is almost honey-like in consistency. It behaves in the opposite way to conventional polymers during the molding cycle. To keep LSR in its semi-liquid state before it arrives in the mold, the injection barrel is water cooled. Once it arrives in the mold, the material is heated and cured.
TMD: Is special equipment required?
NF: To mix and process the material, you need equipment that can deliver the stability required to handle an optical grade silicone material. Although there are examples where traditional molding machines have been adapted with an LSR injection unit, molders may find that part quality or efficiency is compromised.
Sumitomo Demag recently launched a ready-to-use precision IntElect LSR injection molding package. The all-electric IntElect 130 is equipped with a special screw, a non-return valve, vacuum pump, and toggle technology. The cell was developed with numerous partners, including Nexus.
Nexus designed the four-cavity LSR matrix light mold and supplied the mixing and dosing unit, which stabilizes dosing and ensures a precise mixing ratio, irrespective of dosing volumes. The unit also performs automatic venting to detect and purge air from the material before it is fed into the machine and mold.
To optimize LSR component quality, Nexus offers a cold-runner control technology that enables direct injection into each individual cavity via a needle valve gate, balancing each mold cavity filling.
Sumitomo Demag’s IntElect LSR injection molding system
TMD: How is the molding machine different from the standard IntElect?
NF: Special screws, measuring between 14mm and 45mm in diameter, with a sealing system at the shaft, are adapted to the material and machine size. Currently, the LSR package is available on IntElect machines ranging from 50 metric tons to 180 metric tons.
Other special features include a spring-loaded non-return valve to avoid uncontrolled backflow of material, a shut-off system designed for LSR, and a pressure controlled vacuum sequence to extract air and prevent flash during mold filling.
Sumitomo Demag’s Centre Press Platen ensures high rigidity and uniform distribution of clamp force for more balanced pressure distribution. A robust linear guidance system controls the mold opening and closing sequence with a built-in staged clamp force, further reducing flash risk.
TMD: Do manufacturers need a cleanroom?
NF: Typically, a standard all-electric molding machine such as the IntElect is an enclosed cell and holds little risk to cleanliness. However, parts being produced for the medical and life sciences sector are governed by stricter manufacturing hygiene guidelines. These instances may require investment in a certified cleanroom, limiting exposure to airborne particulates, contaminants, and pollutants.
MIT researchers 3D-printed soft electronically active polymers into a number of devices, including a pliable neural electrode, and (shown here) a flexible circuit.
Images: Courtesy of the researchers
One of our most vulnerable organs, the brain is soft, while brain implants are typically made from metal or other rigid materials that can eventually cause inflammation and scar tissue buildup. In response, Massachusetts Institute of Technology (MIT) engineers are developing soft, flexible neural implants that can conform to the brain’s contours and monitor activity without aggravating surrounding tissue. Such alternatives may also be useful in implants that stimulate neural regions to ease symptoms of epilepsy, Parkinson’s disease, and severe depression.
Led by Xuanhe Zhao, a professor of mechanical engineering and civil and environmental engineering, the research team has developed a way to 3D print neural probes and other electronic devices that are as soft and flexible as rubber.
With 3D-printing, the team has also made soft multi-electrode arrays that can monitor the activity of individual neurons.
The team transformed the consistency of an electrically conductive polymer from a liquid-like substance into something closer to viscous toothpaste. That material can be fed through a conventional 3D printer to make stable, electrically conductive patterns.
The team modified poly (3,4-ethylenedioxythiophene) polystyrene sulfonate, or PEDOT:PSS, a conducting polymer typically supplied in the form of an inky, dark blue liquid. The liquid is a mixture of water and PEDOT:PSS nanofibers. Nanofibers provide conductivity when they come in contact, act as a sort of tunnel through which any electrical charge can flow.
To thicken the polymer while retaining the material’s inherent electrical conductivity, the team first freeze-dried the material leaving behind a dry matrix of nanofibers. Then they remixed the nanofibers with a solution of water and an organic solvent to form a hydrogel.
They made hydrogels with various concentrations of nanofibers and found that a range between 5% to 8% by weight of nanofibers produced a material that was both electrically conductive and suitable for feeding into a 3D printer.
As a proof of concept, they printed a small, rubbery electrode, about the size of a piece of confetti. It consisted of a layer of flexible, transparent polymer, over which they printed the conducting polymer, in thin, parallel lines that converge at a tip, measuring about 10µm wide. They implanted the electrode inside a mouse’s brain and found it could pick up electrical signals from a single neuron.
In principle, such soft, hydrogel-based electrodes might be more sensitive than conventional metal electrodes because most metal electrodes conduct electricity in the form of electrons, whereas neurons in the brain produce electrical signals in the form of ions.
“The beauty of a conducting polymer hydrogel is, on top of its soft mechanical properties, it is made of hydrogel, which is ionically conductive, and also a porous sponge of nanofibers, which the ions can flow in and out of,” says Baoyang Lu, one of the co-authors. “Because the electrode’s whole volume is active, its sensitivity is enhanced.”
Posted by Elizabeth Engler Modic
