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Electrospinning is a powerful technique
for producing fibers by using an electrical force to draw small diameter
threads from polymer solutions. The process is fairly simple and has
been refined extensively in the past decade or two. Electrospun fibers
are used extensively in myriad applications - from medical to
filtration, cosmetics, nonwoven textiles, and more.
While electrospinning is a suitable
process for fiber production, the usefulness of the fibers can be
greatly amplified by using different materials in a process called
coaxial electrospinning. When two immiscible liquids are supplied via
two different dispensing syringes to a coaxial spinneret, a core-shell
nanofiber can be produced.
In order to successfully make core-shell
fibers, the coaxial spinneret must exhibit a number of characteristics.
Here is the checklist:
- Excellent electrical conductivity.
Our ramé-hart prebuilt and custom coaxial needles are fabricated
from premium polished Type 304 Stainless Steel which is welded to
Luer hubs for excellent conductivity. The inner component and outer
component are sealed with a PTFE washer. However, under the washer
the two components are joined using metal-to-metal contact for
excellent conductivity throughout the entire spinneret assembly.
- Optimal connectivity. All of our
spinnerets feature the industry-standard female Luer lock interface.
Coaxial needles can be connected directly to a syringe with a male
Luer lock connection or can be connected via our
PTFE Tubing Kit. We also offer
couplings for connecting to flexible tubing - such as
Tygon. The custom coaxial needle can be configured so the two
inlets are parallel (Style C) and at any distance required (DIM E).
See worksheet
here.
ramé-hart Coaxial Needle with Luer
Lock Inlets
- Excellent concentricity. In order
to produce core-shell fibers with a uniform shell thickness, it's
critical that the inner needle is concentric to the outer. We use a
proprietary technique that ensures concentricity no matter what
gauge tubing is used. This is a standard feature on every ramé-hart
prebuilt and custom coaxial needle.
ramé-hart Coaxial Needle with
Excellent Concentricity
- Easy to clean. All of our prebuilt
and custom spinnerets can be disassembled for cleaning. The
image below shows how easy to take apart a ramé-hart coaxial
needle. We offer a
wrench to facilitate this as well as
cleaning wire kits and
needle files.
ramé-hart Coaxial Needle Disassembly
Instructions
- Dimensional flexibility. While our
prebuilt coaxial needles are preconfigured for the most popular
settings, our
custom coaxial needles can be highly optimized. DIM C, for
example, allows the inner needle to be precisely positioned beyond,
inside, or flush with the outer needle as required by your unique
application. You can also control the needle length (DIM F) and side
inlet (Style A, B, C, and DIM E).
ramé-hart Custom Coaxial Needle
Worksheet (click
to enlarge)
- Long life. All ramé-hart
spinnerets are designed for hundreds of uses. In order to maximize
your investment, we offer replacement
PTFE Washers which can wear out and become compressed after many
uses. We also offer additional inner needle components as they tend
to wear out first.
- Gauge flexibility. We offer
needles from 5g to 33g. Coaxial needles can be made from sizes 5g to
28g which are all kept in stock. Even gauges are available in longer
lengths than odd. For inside and outside diameter dimensions, check
out our
needle chart.
- Ease of ordering. We've tried to
make it as easy and flexible as possible to order a custom
spinneret. To get started with a coaxial spinneret, start on this
page. We accept credit card, bank wire, and other forms of
payment. We can ship to any address on the planet earth.
Online Ordering for ramé-hart
Coaxial Needles (click
here
to go to the store)
- Availability. We keep all prebuilt
spinnerets in stock and ready for immediate shipment. Custom
spinnerets are made and shipped within one week. We even offer an
expedite option if you're in a rush.
- Quality. Each spinneret product is
flushed and tested for leaks and flow. Each dimension and feature is
also inspected prior to shipment.
- Warranty. We warranty all
spinneret products for one year. Fewer than 1% of our spinnerets are
returned for warranty repair or replacement.
- More than coaxial. We also offer
prebuilt and custom
triaxial and
quadaxial needles as well as
multi-channel and
side-by-side spinnerets and
spinneret arrays.
ramé-hart Side-by-side Spinneret
- Beveled Tip Option. There are some
applications which work best if the tip of the needle is beveled.
This option is available on custom coaxial, triaxial, and quadaxial
needles.
ramé-hart Custom Triaxial Needle
with Optional Beveled Tip
- Imitated but peerless. Imitation
is the ultimate form of flattery. There are a couple of vendors in
China and India who have attempted to copy our proprietary coaxial
needle design but their products are inferior on every point above.
And while we admire the do-it-yourselfers, many have turned to us
after they realized how challenging it is to make a quality coaxial
spinneret that actually works.
- Volume. Whether you need one, two
or 100 coaxial needles, we are setup to provide you with your
spinneret needs. For large volume orders, please
contact us
for a discounted price and lead time.
Whatever your application is, we can
provide the spinneret and tubing parts. Please feel free to
contact us
if you have a special spinneret application that does not conform to our
prebuilt or custom designs. We make all types of custom
and special-order spinnerets to meet your exacting specifications.
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