Design Considerations for Biomedical Textiles: Fiber vs. Yarn

When terms like “yarn”, “fiber”, and “filament” are used, you might, at first, think that these terms are synonymous. In this blog, we’re going to disentangle the definitions, comb through the types, and dispel the looming cloud of uncertainty, so that you may weave the terms into your sentences with expertise.

When it comes to textiles, there is some additional nuance in the terminology, of which you might not be aware. Fibers, are threadlike strands of material that are significantly longer than they are wide, with an aspect ratio of 100:1. Fibers come in both synthetic and natural forms, ranging from polyesters to silk to cellulose (cotton). Fibers can also be divided up into filament and staple fibers. Filaments are continuous long lengths of fibers (measured in yards or meters) and staple fibers are short lengths (measured in inches). Filament fibers can come in two different forms – monofilament and multifilament – and are produced by extruding polymer through a spinneret to form either a single-strand or multiple-strand filament, respectively.

Yarns are multi-filament meaning they are comprised of a plurality of individual filaments that form a bundle. Yarns are measured in the common textile vernacular of denier, which can be defined as linear density or (mass (g)/9,000 m). Fibers are singular filaments in nature, comprised of a lone solid filament. The choice between using a monofilament or multifilament depends on the target application. For example, a monofilament will have decreased surface area and will be more rigid, compared to a similarly-sized multifilament. Multifilament-based meshes have superior drapability, and a noticeably softer texture, over monofilament-based meshes. Furthermore, your application may need to alter the filament’s denier (linear density) or tenacity (tensile strength), which we can tailor using our variety of polymers or by varying process parameters.

If you are looking to use an extruded bioresorbable fiber or textile in your next medical product, contact us at sales@poly-med.com for more information.

Poly-Med, Inc. Celebrates 25 Years of Innovation in South Carolina

Poly-Med, Inc., one of the first biotech companies creating bioresorbable polymers for use in medical and pharmaceutical devices is celebrating an important milestone in their history this year; 25 Years of Innovation in South Carolina.

Poly-Med, Inc. was founded by Dr. Shalaby W. Shalaby, considered one of the forefathers of the bioresorbable polymer industry. He was one of the lead inventors for several bioresorbable products that we still use today, notably, the Vicryl®suture.

Dr. Shalaby came to South Carolina in 1990 to teach and conduct research at Clemson University. He launched Poly-Med, Inc. in 1993, as a means to translate his research into medical therapies, as well as to mentor, teach, and sponsor former and current students’ continuing education.

Today, under Dave Shalaby, Dr. Shalaby’s son, Poly-Med, Inc. creates first-in-class transformative bioresorbable medical devices and pharmaceutical products, which have improved millions of patient’s lives. Poly-Med, a once small startup, has been built into a sustainable technology company that attracts and retains the best engineers, scientists, and collaborators from around the world. Dr. Shalaby had a vision when he started Poly-Med, Inc. in South Carolina. He enabled many employees to gain experience, share ideas, in a collaborative effort, and help lay the foundation for the next generation of bioresorbable polymers and medical devices. Under Dave Shalaby’s, leadership, Poly-Med, Inc. has been taken to the next level, and continues to support and improve on the things his father held dear, the application of research,  education, and fostering innovation..

“The work we do at Poly-Med is meaningful in so many ways. As a researcher, we have a chance to work with the most advanced materials and technologies. As a product developer, we work to create first-of-their-kind products to help solve unmet needs. As a collaborator, we get to work with people and companies around the world in a way that we could not have ever imagined. This is how we continue to grow the history of Poly-Med – taking chances, identifying (sometimes hidden) talent, and building new ideas into a meaningful reality.” – Scott Taylor, CTO.

Through continued improvement in personal and professional growth, Poly-Med, Inc. employees are ready and excited to further advance and innovate in the medtech and biotech industries and continue making strides to improve patient quality of life through the devices they manufacture.

Resorbable Ligation Device Elicits Successful Preliminary Results

Poly-Med, Inc. (PMI) is thrilled to share the success of the LigaTie®, a device designed and developed by Resorbable Devices AB in Uppsala, Sweden that utilizes one of Poly-Med’s Glycoprene® polymers. The LigaTie® device was developed by Dr. Odd Viking Höglund (http://bit.ly/innovator-LigaTie) and addresses challenges associated with ligation during surgical procedures. The device is utilized to restrict blood flow, prevent blood loss, and prevent air leaks, when used on lungs or airways. PMI supports Resorbable Devices AB in the material development of a novel, flexible, fast degrading, absorbable polymer that has been able to meet the demanding specifications of the LigaTie® device. The current product scope initially focuses on veterinary applications, and Resorbable Devices AB has seen great success with clinical results to date.

The LigaTie® has been successful in the following veterinary procedures: in vivo canine neutering, ligation of ovarian pedicles 1, 2 and spermatic cords,3 ex vivo cholecystectomies (removal of gallbladder) to seal the cystic duct,4 ex vivo sealing of lung tissue at lung biopsies,5 in vivo lung lobectomy in dogs with lung cancer,6 and a video-assisted thoracoscopic lung lobectomy (removal of lung lobe).7 The LigaTie® design is based on the concept of a cable tie, and the design allows for ligation of a single artery. The device is a flexible, unidirectional, self-locking, loop device produced from one of PMI’s Glycoprene® absorbable materials (https://poly-med.com/services/implantable-grade-polymers-catalogue/).

Permanent surgical sutures, and other non-absorbable devices (i.e., clips, cable ties, staples), may be used for ligation applications, but threaten to cause negative tissue responses, such as infection, inflammation, or chronic granulomas/scar tissue formation. On the other hand, the LigaTie® exhibits the following benefits due to the novel design and material choice: good tissue grip, easy and minimally invasive placement, which results in a reduction in surgery time (compared to suture ligation), standardized and secure locking mechanism, minimal inflammatory reactions, and acceptable responses for the mechanical performance-to-resorption profile. The preliminary results for the LigaTie® device are extremely promising and truly offer an innovative product for tissue ligation to prevent hemorrhage or leakage of air.

PMI is excited to support companies working to address challenges in the biomedical engineering and biotechnology fields. With PMI’s vertically integrated structure, they are capable of assisting clients take their ideas from exploration and investigation to final manufacturing and market, through in-house material development, analytical testing, product development, and project management. Connect with PMI today to hear more about our material offerings and design, development, and analytical capabilities! If you are interested in hearing more about how Poly- Med can help advance your idea or product, please reach out to us at sales@poly-med.com.

Brittany Banik, Ph.D.
Account Manager
Business Development, Poly-Med, Inc.

1 Höglund, O., et al. (2013). 27(8), pp.961-6. doi: 10.1177/0885328211431018.
2 Da Mota Costa, M., et al. (2016). BMC Res Notes, 9(245), pp. 1-6. doi: 10.1186/s13104-016-2042-2.
3 Höglund, O., et al. (2014). BMC Res Notes, 7(825), pp. 1-7. doi: 10.1186/1756-0500-7-825.
4 Tepper, S., et al. (2017). Can J Vet Res, 81(3), pp. 223-7. PMID: 28725113.
5 Nylund, A. et al. (Accepted). Vet Surg. Evaluation of a resorbable self-locking ligation device for performing peripheral lung biopsies in a caprine cadaveric model.
6 Ishigaki et al. (2017). Presentation at ACVS Surgery Summit. doi 10.1111/vsu.12710.
7 Guedes, R., et al. (2018). Surg Innov., 25(2), pp. 158-164. doi: 10.1177/1553350617751293. Link to video.

Bioabsorbable Medical Device Manufacturing: Poly-Med Approach to Product Development

Leading a medical device product development project is always exciting, especially when you are in the resorbable polymer space! One of the most significant milestones is the Design Verification and Validation stage, which requires clinical evaluation.

Answering probing questions is imperative for any medical device product that is being developed, but it becomes even more significant, and challenging, for a novel, marketable, and resorbable device/component. In fact, Poly-Med, being the leader in resorbable materials, understands the importance of this milestone for a clinical trial, and as such, has become the pioneer in developing resorbable components and devices that can perform (at a minimum) like their non-resorbable counterparts, while ensuring the novel device meets unmet market needs.

Poly-Med’s approach to a successful clinical trial, is to set up the design inputs, while planning for verification and validation testing. The biggest challenge for a clinical trial coming up for any device, including resorbables, is having design inputs that will ensure your designed medical device meets the intended uses, as well as the user needs, while still ensuring your processes can meet rigorous design inputs.

Some of the most common items that can be overlooked during the development of a medical device, that are critical for the clinical trials, really fall into the following categories:

– Unclear definition of user needs for the resorbable device

– Not capturing all performance, functional, regulatory, and safety requirements that are required due to the use of a resorbable material

– Ensuring your acceptance criteria (or final device specifications) meet the user need and performance of the device

In addition, without the resources, processes, design inputs, and plan, product development can become an iterative process, which ultimately, will cause scope, time, and going over budget. In summary, the critical task is developing new (scalable, efficient) processes that will allow you to meet your functional design inputs, while still meeting your milestones and budget.

Here is what makes Poly-Med successful during a medical device product development project:

– Resources: Design Verification testing. Without a good plan, things can swirl out of control. Planning for enough resources to keep testing under control, to ensure meeting your other milestones, is critical.

– A Design Verification Plan: Having a strong plan will ensure meeting your milestones and avoiding scope creep. Hence, why it is ideal to start thinking about how you would do Design Verification as you are defining your Design Inputs – this will aid with having a strong, successful Design Verification plan.

– A Good Team: Work ethic is the most important attribute the individuals at Poly-Med have. This allows the teams to create solutions efficiently and fast.

– A Strong Quality Team: Poly-Med’s quality team always ensures the device/component is meeting your Design Controls, which are critical for the success of the project.

If you are interested in learning how Poly-Med can take your idea and translate it into a first-in-class resorbable medical device contact us!

Anna Paola Soliani, Ph.D.
Key Account Manager

Poly-Med Launches Poly-Med 3D

Poly-Med, Inc., the leader in bioresorbable solutions, announces the launch of Poly-Med 3D Printing a vertically integrated design and custom manufacturing advantage that produces specialized materials, with innovative design supported by, and in-house fused filament printing services for, the medical device industry.

Poly-Med 3D Printing enables more efficient development of bioresorbable devices for the medical world, resulting in faster development to market for prototype and ready to manufacture leading edge medical devices.

Ever since Charles Hull first proposed the three-dimensional (3D) printing process in 1984, the technology has developed rapidly and well beyond what originally seemed possible. 3D Printing and moreover, additive manufacturing, has emerged as a formidable force in the ever-expanding medical device and pharmaceutical fields. Now, 34 years since that first inspiration, the promise of additive manufacturing of absorbable medical implants, pharmaceuticals, and scaffolds for tissue replacement is a reality.

Poly-Med’s focus on bioresorbable materials and their development into first-in-class medical devices, has been developed and delivered for the medical market for the past 25 years. With the ability to provide fully traceable, medical-grade polymers and filaments for additive manufacturing, Poly-Med’s materials offer distinct advantages by their unique properties based on their composition, architecture, and desired performance. Poly-Med’s bioresorbable materials are not only guaranteed to have the best quality standards, they also provide innovative properties that yield a better printing experience, coupled with enhanced device functionality.

With over 910 polymer solutions, we are continuously developing bioresorbable materials for your device needs. If you have a device in mind that’s absorbable, Poly-Med is able to prototype it, or fully develop it, with 3D Printing Services.

For more information visit Poly-Med 3D Printing at www.poly-med3d.com or contact the team at sales@poly-med3d.com.

Seth McCullen, Ph.D.
Manager, Business Development

Did you know Poly-Med, Inc. Provides Analytical Services?

At Poly-Med, analytical testing has been and continues to be a cornerstone of our key technological advancements in bioresorbable materials. In our formative years, our early developmental work utilized a vast array of in-house testing equipment to characterize, refine, and create our extensive polymer suite. As an added benefit of our years of growth and accumulation of laboratory skills and equipment, we can offer our extensive analytical capabilities to you – our clients – to support the development of your medical device and pharmaceutical products.

In polymer science, it is important to assess the structural integrity at different processing steps via inherent viscosity (IV) measurements. This information provides insight to the extent of degradation in a polymer, and can give a snapshot of the overall state of the material. Additionally, our polymers can be characterized using difference scanning calorimetry to determine key material characteristics like glass transition and melt temperatures. Our capabilities also include both gas chromatography (GC) and gel permeation chromatography (GPC) to determine residuals, polydispersity, and other molecular attributes.

We frequently extend these services to our clients both within, and independently of, our design and development projects. Poly-Med aims to be a trusted long-term partner for your product’s development – and that includes analytical testing needs. To meet the specific needs of our clients, analysis can be performed on an as-requested basis, or as part of release testing. We perform analysis according to consensus standards and develop custom test methods as needed. Customers benefit from our broad capabilities, fast turn-around time, and quality of service. Visit our analytics page here to see our full service offerings. Contact us at sales@poly-med.com for specific questions about our services or the development of testing protocols.

James Turner, Ph.D.

Electrospinning for Bioresorbable Medical Devices

Electrospinning is a fiber production method which uses electric force to draw charged threads of a polymer solution or melt into fibers with diameters in the nano to micron size-scale. While this sounds like science fiction, it is a process that dates back to the early 20th century and continues to be at the forefront of biomedical engineering today. To date, pioneering research and development projects continue to validate its immense potential. In the biomedical and biomaterials communities alone, electrospinning has been widely utilized in disciplines such as: regenerative medicine (i.e., vascular, tendon/ligament, cardiac, neural, and wound healing), nanomedicine/drug delivery, cancer therapy, dentistry, and biosensors.

The set-up is simple and straightforward and includes three (3) main components:

1. Spinneret: A pump/polymer feed that distributes a polymer solution/melt at a controlled flow rate

2. High voltage source: Electrical force is applied to the spinneret, which accelerates the polymer solution as a jet from the spinneret tip to the collecting target

3. Collecting target: Accumulation area for fibers to build a fibrous construct, it can be designed for various applications and fiber orientation specifications (i.e., drum, blade collector, metallic plate, and array of parallel or counter electrodes)

Electrospinning yields fibers with remarkable properties. The resulting fibers are continuous, can be produced to submicron architectures, and exhibit high surface area-to-volume ratios and inter-/intra porosity. The electrospinning technique also allows for control over mechanical properties, microstructure, degradation rates, and downstream cellular and tissue level responses. Combining these benefits with the advantages of bioresorbable materials and devices can yield remarkable improvements in modern medicine which include:

• Eliminating the need for invasive secondary surgery intervention since the bioresorbable polymer is metabolized via physiological biochemical pathways

• Providing porous, supportive scaffolding for cell guidance, migration, and development until natural tissue replaces the implant/device

• Imitating structural tissue complexity by being able to build structures from the nano, micro, and macro-scale

Poly-Med, a world leader in bioresorbable polymers, has utilized electrospinning to develop bioresorbable scaffolds and devices for improved tissue regeneration, restoration, and function. Poly-Med has the ability to provide industrial scale electrospinning services for a range of bioresorbable polymers that meet not only mechanical and degradation requirements but are also viable in the human body.

This revolutionary technique carries great promise for advancing not only the field of biomedical engineering but also improving human lives and expanding upon traditional mesh based technologies. If you are interested in hearing more about Poly-Med’s electrospinning capabilities or have an idea for an electrospun component or device, please contact us today!

Biomedical Textile Constructs: Warp vs. Weft Knitting

Vertical integration at Poly-Med allows us to utilize our own unique materials for a vast array of downstream processing. We use bioresorbable polymers made in-house every day for custom applications in 3D printing, fiber extrusion, electrospinning, and more! This allows us to efficiently move a unique material from raw material processing into a fully formed device component. This vertical integration gives us a unique advantage in the medical textile industry, as we are able to manufacture custom, medical-grade textiles from raw materials to final products under one roof.

Of the many ways to produce textile products suitable for medical devices, warp knitting and weft knitting (circular) are some of the most commonly used in medical and other textile industries, including extensive use in the apparel industry. Each method offers unique benefits and final properties, so choosing the correct one for a specific medical application can be critical! At Poly-Med, we can help you decide which production method best suits your specific application.

Weft Knitting:

Weft knitting requires only a single yarn feed and produces a very simple stitch so that the created stitches interlock the yarn with itself. The result is a tubular knit fabric with very high flexibility and stretch. The single yarn input allows for production of very thin fabrics at a variety of fabric widths. For unique applications, the production of a tubular fabric can even allow for 3D constructs with minimal or no seams. One of the main benefits to weft knitting is cost. This knitting method only requires the single yarn feed, so trial runs can be conducted with minimal material input requirements and fewer processing steps to get started. Weft knitting can be used to produce very narrow fabrics, further reducing costs to trial out unique materials or applications. Processing times are generally short and are easily scaled between short, one-off trials and mass production.

Warp Knitting:

Warp knitting allows for many more customizations to the fabric materials and properties. Unlike the single yarn feed used in weft knitting, warp knitting requires individual ends to feed in across the entire width of the fabric. This requires some additional work to prepare the material for knitting, but offers more options for a custom fabric. Striping can be incorporated along the length of the fabric by mixing materials and the stitching pattern can be fully customized for each yarn input end. Unique combinations of materials and stitching patterns allow for very custom fabrics designed to meet specific attributes and mechanical properties. The resulting material is often more dimensionally stable and less prone to runs than weft-knit products.

Weft knitting and warp knitting represent only two (2) of the capabilities at Poly-Med to produce unique medical device components using bioresorbable polymers. If you are working on a medical device and are interesting in learning more about degradable polymers and how to process them, contact us to learn how we can advance your idea.

Independent Evaluation of Poly-Med’s Bioresorbable Medical Grade 3D Printing Filaments

Poly-Med has recently been in collaboration with Queensland University of Technology to promote research of our unique, bioresorbable medical grade 3D printing filaments. The latest publication, authored by Mina Mohseni, Professor Dietmar Hutmacher, and Dr. Nathan Castro, highlights performance of these filaments in fused filament fabrication (FFF) additive manufactured (AM) tissue scaffolding. Specifically, this research sought to characterize material properties and evaluate potential use in both hard and soft tissue engineering applications.

As Mohseni et al. notes, additive manufacturing has established itself as an advantageous method for fabrication of unique and physiologically relevant structures to support tissue growth. Equally important in selecting the correct scaffolding structure, choosing the appropriate material is also vital for successful tissue ingrowth. Currently, Poly-Med offers four medical grade filaments for 3D printing: Lactoprene® 100M, Max-Prene® 955, Dioxaprene® 100M, and Caproprene™ 100M. The bioresorbable nature of these filaments make them ideal candidates for tissue scaffolding applications and use in regenerative medicine.

Through extensive physiochemical analysis of these four filaments, Mohseni et al. concludes that all filaments are viable options for tissue scaffolding, with each material having unique properties to fit a range of soft and hard tissue applications. For example, it was noted that Dioxaprene® 100M exhibits softness and flexibility, making it an ideal choice for soft tissue engineering. Caproprene™ 100M displays similar mechanical properties as those of Dioxaprene® 100M, however Caproprene™ 100M strength and mass loss occurs over a much longer time frame. Thus, while Dioxaprene® 100M and Caproprene™ 100M are both soft tissue-oriented, either can be selected depending on the desired degradation timeline.

For hard tissue applications, materials with a higher stiffness are often preferred. To this effect, Poly-Med offers Max-Prene® 955 and Lactoprene® 100M, which both exhibit an elastic modulus suitable for hard tissue regeneration, with values in the range of 63-89 MPa. In fact, elastic modulus and other mechanical properties of these materials can be tuned by adjusting scaffold pore size, % infill, which Mohseni et al. further details in the article.

Poly-Med offers four unique bioresorbable filaments for 3D printing, each with its own niche and range of potential applications. Mohseni et al. has provided an extensive review of the physiochemical properties of these filaments that can help guide any device manufacturer in the right direction when determining which material is best for a given product. As always, feel free to contact Poly-Med for assistance with any aspect of additive manufacturing – we are here to be a creative partner as you bring your solution to market. Contact us for more information regarding our bioresorbable 3D printing filaments.

Brad Johns, M.S.

To see the original Queensland University of Technology evaluation: http://www.mdpi.com/2073-4360/10/1

3D Printing of Medical Devices: Poly-Med’s Perspective on FDA Guidance

After publishing a draft guidance document for additive manufacturing medical devices in 2016, the FDA issued its highly anticipated Technical Considerations for Additive Manufactured Medical Devices in December 2017. The latest volume on 3D-printed devices focuses heavily on advising manufacturers on 3D-printing-specific focus areas to consider when developing a new additive manufactured device.

The guidance document is divided into two primary sections: device design/manufacturing and testing. The former section outlines general steps that must be taken in the development process. To begin the general flow of additive manufacturing device design, a computer model must first be created. This part file can be generated using any of a number of 3D-modeling software. In cases where a patient-matched device is being fabricated, additional software may be required to convert scans of patient anatomy into a viable model file. Next, the model is converted into a part file which actually allows for printing. The part file communicates to the printer how the design will be assembled. Using the appropriate equipment, the part is then printed according to the printer software inputs and part file assembly instructions. Some parts may then be post-processed to remove residues or any other printing defects from the part.

The guidance document also speaks to the importance of using quality materials in the additive manufacturing process. Poly-Med recognizes material selection as being critical to device success. PMI specializes in production of traceable, medical-grade filaments, which are ideal for medical device design and manufacturing in the 3D-printing space. Further, choosing the appropriate material for a given application is also crucial. As the device designer, it is of the utmost importance to consider mechanical properties (stiffness, strength, etc.) as well as degradation time frames for bioresorbable products. Poly-Med offers a wide array of materials with numerous combinations of mechanical properties and degradation times to fit almost any application.

As a source of experienced medical device and component design, Poly-Med is committed to adhering to the new guidance document and providing expertise in development of 3D-printed medical devices. PMI is already in collaboration with a number of clients who are committed to additive manufactured products at various stages of device design.

If you are working on a medical device application and are interested in learning more about our additive manufacturing capabilities with bioresorbable polymers, Contact Us to learn how we can advance your idea.

Brad Johns, M.S.