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The Spinneret
Fall 2022

A Quarterly Newsletter from ramé-hart devoted to Coaxial, Triaxial, Quadaxial and Custom
Spinnerets used for Electrospinning, Bioprinting and Related Applications


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Tips and Tricks for Successful Coaxial Bioprinting

The most common method for bioprinting two materials simultaneously is via coaxial extrusion in a core/shell configuration using different bioinks. In some cases, the outer shell is sacrificial while the core material is cell-laden. In other configurations, both the core and shell contain cultures. And in yet other cases, the core may be hollow while the shell is cell-laden.

By using a multi-lumen coaxial needle, it's possible to extrude a number of filaments all surrounded by a single shell. See the examples below of multi-channel coaxial needles. 

ramé-hart Custom Multi-Channel Coaxial Needles

The bioinks used in coaxial bioprinting include cell-laden materials, sacrificial (non-cell-laden) materials, hydrogels, and crosslinking solutions. It's possible to create nanotubes by using a crosslinking solution for the inner flow. By using a triaxial or quadaxial needle, it's possible to add additional layers of material. Multilayered filaments, for example, can be designed to emulate tissue found in vascular systems and other similar structures. The types of bioinks can also affect the success of the design. For example, the viscosity and needle gauge will drive the required extrusion pressure. If the required extrusion pressure exceeds the capacity of the pump, the coaxial extrusion may fail if an external pressure pump is not added to the setup.

It's not surprising then that materials with lower viscosity often will work best. Thickeners made from nanoparticles should also be used with caution as they increase the risk of clogging. If clogging does occur, all ramé-hart coaxial needles can easily be disassembled for cleaning following the instructions at this link. You will also need a disassembly wrench and cleaning wires.

Flow rates and pump pressure settings should also be considered as these will determine the relative diameters of the core and thicknesses of the shell components and additional layers. Trial and error is likely to be required to find optimal results in many cases.

If your bioprinting application requires a special coaxial needle such as a multi-channel design, or anything that falls outside of our prebuilt or custom coaxial needle designs, don't hesitate to contact us with your specifications. We specialize in special orders.

Survey Results

This summer we sent out a survey to a selection of our spinneret customers to better understand their needs. If you already participated, we thank you. We'd like to share some preliminary results with you:
  • For the first time, bioprinting outpaced electrospinning as the top application for ramé-hart spinnerets, 43% to 29%. Other applications among the responders were: encapsulation and wet-spinning.
  • 57% of customers found us on Google. 14% found us from a published research paper. Others heard about us from a colleague or were already existing ramé-hart customers.
  • 100% of responders indicated they would recommend ramé-hart to a colleague. Thank you for your trust and confidence.
  • 57% are "very satisfied" with ramé-hart products while the remaining 43% are "satisfied".
  • The majority of those responding indicated a high rating for quality, usefulness, and uniqueness.
  • 100% indicated that the spinneret product they purchased met their needs.
  • 100% also rated product quality either "excellent" or "very good".
  • 86% gave a favorable rating for "value for the money".
  • 100% were happy with delivery time. We strive to over-deliver.
  • 100% said they were either likely or very likely to purchase another ramé-hart spinneret product.

If you did not already participate in the survey, and you've purchased one or more ramé-hart spinnerets, and wish to participate, we would like to offer you $60 in store credit for your participation and it will only take about two minutes to complete the survey. Simply click on this link to start the survey. We will send you a $60 credit afterwards.

What's New

In June we released a new spinneret product, our Custom Coaxial Needle with Tubing. Instead of traditional female Luer connections, we offer press-to-connect fittings that mate perfectly with our PTFE tubing. For the complete press release, please visit this page. For more information or to order a Custom Coaxial Needle with Tubing, please visit this page and then scroll down to BOX 3.

Custom Coaxial Needle with Tubing p/n 100-10-COAXTUBE

Promo Codes for our Customers

If you made it this far, we'd like to treat you to savings. Use either of the following coupons on your next spinneret order.

Fine print: Limit one coupon code per order. Limit one use per customer. To receive the discount, order must be placed online at www.ramehart.us and paid for with a credit card. Enter the coupon code during checkout. All coupon codes above expire on 1-Jan-2023.


Carl Clegg
Director of Sales
Phone 973-448-0305
Contact us



Visit ramé-hart on Facebook    Visit ramé-hart on Twitter    Watch ramé-hart Videos    Look at ramé-hart's pictures on Flickr    Subscribe to our Monthly Newsletter    Visit ramé-hart on Linkedin