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The Spinneret
Winter 2017
A ramé-hart Newsletter Covering Coaxial and Triaxial Needle Products


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Choosing the Best Needle Gauge for Electrospinning
There are a number of variables that affect the properties of single-component electrospun fibers. In electrospinning, a polymer solution is sprayed through an electrically charged needle to create nanofibers. In general, the most desirable needle gauge will be the highest possible gauge (i.e., the smallest possible diameter) that will produce the minimum possible diameter nanofiber without any problems with the process. As the gauge is decreased (resulting in a larger diameter), the nanofiber diameter increases. For this application, we have a wide variety of stainless steel needles that range in size from 10 gauge to 33 gauge.1

Coaxial needles2 (or spinnerets) are used for bi-component electrospinning. By using different polymer solutions for the inner and outer flow, a variety of characteristics can be achieved at the nanofiber level. Typically, the inner component will be the solution with better spinning properties. The outer polymer can lower spinnability but may offer other desirable properties. The end result is a product with unique characteristics for both the core and shell components of the nanofiber. A coaxial spinneret can also be used to produce hollow microfibers. Using our worksheet3, Dimension C can be specified to further customize the coaxial needle parameters.

Pair of ramé-hart Custom Triaxial Needles (Style B Inlet)

Triaxial needles4 (or spinnerets) offer yet another layer for either a tri-component nanofiber or a hollow bi-component nanofiber. The properties of the tri-component fiber can be further enhanced by adding this additional component. In fact, on several occasions, we've made quadaxial needles allowing for the creation of fibers with four components.

Ultimately, some trial and error may be necessary to discover the ideal needle gauge. We can help with this challenge in the following ways:

1. We offer on our coaxial needle products an option that allows for a second inner component. On request, we can make each inner coaxial needle component with a different DIM C value and even a different gauge. Note that the dimples will be placed on the outer needle with the lower inner gauge installed possibly leading to less that full concentricity between the inner and outer needles when the higher gauge is installed.

2. We offer fast turn around. Our standard turn-around is one week and our expedited option is just a few days.

3. We offer a number of prebuilt coaxial5 and triaxial6 needles which are already preconfigured for many popular electrospinning applications. We keep these in stock and they are available for immediate shipment.

4. If any of our prebuilt or custom coaxial and triaxial needles don't exactly fit your requirements, please let us know. About 15-20% of our needle products are custom made (outside of the worksheet). All we need is a sketch or description and we can make it to your liking.

Custom Coaxial Needle with (16) Inner Components

1 See http://www.ramehart.us/straight-304-stainless-steel-reusable-dispensing-needle/. For a variety pack, see http://www.ramehart.us/straight-304-ss-needle-assortment/
2 See http://www.customspinnerets.com/coaxial.
3 See http://www.ramehart.com/pdf/coaxial_worksheet.pdf.
4 See http://www.customspinnerets.com/triaxial.
5 See http://www.ramehart.us/prebuilt-coaxial-needle/
6 See http://www.ramehart.us/prebuilt-triaxial-needle/.

Why ramé-hart for Custom Coaxial and Triaxial Needles

1. We've been around with since 1961 and have extensive experience machining and building precision instrument components. Our primary product line is instruments for contact angle goniometry. See www.ramehart.com

2. We are the world's largest supplier of custom and prebuilt coaxial and triaxial needles. No one else comes close. In fact, some of our competitors actually buy their products and parts from us. We sell to everyone at the same fair price.

3. As noted in the prior section, we have ample experience making custom configurations - including designs that don't conform to our standard worksheets and prebuilt designs.

4. Our prebuilt products are in stock and ready to ship. All worksheet-based custom coaxial and triaxial products can be fabricated in one week or less.

5. Our customer service is top notch. Not happy with something, let us know and we'll make it right.

6. We use only top quality components. All needle tubing is 304 Stainless Steel and all Luer hubs are chrome-plated brass. Sealing washers are solid PTFE. All machining is done in house. With our large array of custom fixtures and tools, we can fabricate any coaxial needle to exacting requirements. Over the years, we have added to and improved our techniques and proprietary methods.

7. We also offer a wide array of Luer adapters and tubing to help you get your configuration setup and running fast. See http://www.ramehart.us/coaxial-needles/. We also offer an Electrospinning Check Tool, replacement PTFE Washers, and single component dispensing needles.

Please visit our website at www.customspinnerets.com. If you don't see what you are looking for, contact us and let us know what you require. Chances are we have it or, if not, we can make it.

Thank you for your continued business. We look forward to being of service to you and your coaxial needle needs.


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



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