electrospinning +15kV and -4kV = 19kV

[Winfield Hill]

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals.pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.


--
Thanks,
- Win

 

On 15 Sep 2019 11:49:20 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals.pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.

Fun. I helped Tom Kelly start Imago, the tomographic atom probe outfit
which was eventually acquired by Cameca. It was fun, I got named on a
patent, and spent a lot of money on airline tickets.

 

[Winfield Hill]

jlarkin@highlandsniptechnology.com wrote...

On 15 Sep 2019, Winfield Hill wrote:

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals.pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.

Fun. I helped Tom Kelly start Imago, the tomographic atom
probe outfit which was eventually acquired by Cameca.
It was fun, I got named on a patent, and spent a lot of
money on airline tickets.

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!


--
Thanks,
- Win

 

[Cursitor Doom]

On Sun, 15 Sep 2019 14:39:04 -0700, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high voltages, so much
the better!

How are you generating them? C-W (or variant) style multipliers?



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

 

[Winfield Hill]

Cursitor Doom wrote...

On Sun, 15 Sep 2019, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

How are you generating them? C-W (or variant) style
multipliers?

Standard high-voltage dc-dc converter modules. Most
are proportional types, which means you add a control
system for their supply voltages.


--
Thanks,
- Win

 

Win, If you need any tips or tricks for Espin diagnotics let me know. I spent 8.5 years in a pioneering Electrospinning lab. One of the first things to do is ditch the syringe pump.

Steve.

 

[Jan Panteltje]

On a sunny day (15 Sep 2019 11:49:20 -0700) it happened Winfield Hill
<winfieldhill@yahoo.com> wrote in <qlm13g01du3@drn.newsguy.com>:

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals.pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.

Circuit diagram?
That sort of voltages reminds me of teefee HV.
Would grab old monitor or TV ?

 

[John S]

On 9/15/2019 7:30 PM, Winfield Hill wrote:

Cursitor Doom wrote...

On Sun, 15 Sep 2019, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

How are you generating them? C-W (or variant) style
multipliers?

Standard high-voltage dc-dc converter modules. Most
are proportional types, which means you add a control
system for their supply voltages.

How much output current or power is required?

 

Depends on the carrier solvent, polymer concentration, forced or gravity flow, type of polymer, a ton of things. However a typical single jet in the lab is a few hundred nanoamps.


Steve

 

[Winfield Hill]

sroberts6328@gmail.com wrote...

Win, If you need any tips or tricks for Espin
diagnotics let me know. I spent 8.5 years in
a pioneering Electrospinning lab. One of the
first things to do is ditch the syringe pump.

Steve.

Are there any good publications from your lab?
What did you replace the syringe pump with?


--
Thanks,
- Win

 

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qlml3d094e@drn.newsguy.com:

Cursitor Doom wrote...

On Sun, 15 Sep 2019, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

How are you generating them? C-W (or variant) style
multipliers?

Standard high-voltage dc-dc converter modules. Most
are proportional types, which means you add a control
system for their supply voltages.

Is the ripple any issue?

With x-ray I know that the cleaner the HVDC supply, the cleaner the
flux, and thus the better the contrast ratio of the imagery.

If the supply is overtly noisey, the flux carries so much of it
that the image is very grainy and 'snow-filtrated'.

Seems all you need though are the 'degrees of separation' that 19kV
provides and noise is not an issue as the stream 'spins' out based on
the attraction, not something directly related to the HV excitation
as far as time goes.

 

And one more easy one. While electrostatic deflection of the jet works well, stabilizing its wander can be interesting. One way is to put a say 5 cm diameter #14 wire ring at the top, and shoot through it. Tie it to the nozzle potential.

This works great, especially for imaging or if your using a drum for collection.

We ended up with various means for winding even layers, typically sliding the nozzle assembly back and forth with steppers gets you amazingly uniform sheets. With the caveat that the spinning collection drum is very large compared to the landing circle diameter.

Steve

 

Air pressurization is often superior to the syringe pump, as you remove the sneak conductance path back through the pump body. Air gives you finer control, and if were to look at the fluid pressure over time you'd fine air is smoother.

You can also get a lot of data with laser doppler, the velocities are in the right range that a sound card or simple LabVIEW system sampling at 10 or 100 Khz will give you data.

Other tricks involve dual cameras for 3D, I used to multiplex two NTSC cameras on alternating fields or alternating lines, to get stereo images with a frame grabber.

Dual wedge prisms in front of the camera lens, and a high end camera or a high speed camera also get you 3D.

A green DPSS laser aimed at the straight segment will get you diffraction patterns that correlate well with single slit diffraction math.

Lasers work great for measuring individual fibers as well, and if the diameter gets real small, the fiber's scattering pattern (at right angles to the axis) corresponds to an isotropic radiator, and then the amplitude of the scattering corresponds to the fiber diameter. Ended up reading a lot of Lord Rayleigh's work to calibrate that. Saves a lot of time compared to loading fibers in a SEM.

The shape of the jet "cone" contains a ton of information, but the trick is using a Fresnel lens light source with a mask to keep the direct light out of the camera, and only detect the diffracted light. As the fibers are so tiny, light sources must be immensely bright for filming at high speeds. I ended up using CERMAX lamps and metal halide.

All of this was between ten and twenty years ago, and I'd love to go back to it with today's technology. Especially with modern LED.

I have a few newer methods for measuring jet current that I'm not ready to publish yet, I'll send you an email.

Ballast resistors on the order of 1 Gig work great for creating parallel jets.

The methods for mass production are what I more or less can't discuss..

Steve

 

Search for Darrell Reneker for the publications. The Thesis of Tao Han and Han Xu are really interesting.

Air source can be replaced with a dual solenoid valve assembly with a small chamber between the valves, which dump into a reservoir. Open A, fill chamber, close A, Open B, dump into reservoir, close B. This is my favorite way, short of a MFC, basically Delta Sigma with air. It was not patentable.

Or US patent 8,500,431, my former supervisors way, a Slip Round the Ring, Whetstone bridge for Air...

One of the better discoveries for quality control was that a carefully designed, linear white light source oriented along the straight segment of the jet liberated diffracted light, very much the classical "soap film colors"
and you could infer the diameter of the jet from the pattern of the colors with a camera.

My job was imaging and measurement , using a variety of techniques, as well as design and build of apparatus.

A recent pub, my very simple hardware design, , is:

" A Customized Instrument with Laser Interferometry for measuring Electrospun Mat Thickness" Review of Scientific Instruments 90, 075110 (2019); https://doi.org/10.1063/1.5100137

Problem being since fiber mats are rough on the nanoscale, and are often elastic, you need a way to define what the surface is, and what the test conditions are. The instrument in the above paper is a start, it needs other non-contact probes for the contact to get even better data, and I'm looking at how to do that. But for a quickly designed, sort of hastily designed, instrument, it works well.

Steve

 

[John Larkin]

On 15 Sep 2019 14:39:04 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

jlarkin@highlandsniptechnology.com wrote...

On 15 Sep 2019, Winfield Hill wrote:

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals.pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.

Fun. I helped Tom Kelly start Imago, the tomographic atom
probe outfit which was eventually acquired by Cameca.
It was fun, I got named on a patent, and spent a lot of
money on airline tickets.

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

We get to play with a lot of fun stuff, without spending a decade or
so doing the undergrad/grad/PhD/post-doc thing, working on one thing.

 

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE

 

[John Larkin]

On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE

I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

 

[Bill Sloman]

On Tuesday, September 17, 2019 at 4:29:03 AM UTC+10, John Larkin wrote:

On 15 Sep 2019 14:39:04 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

jlarkin@highlandsniptechnology.com wrote...

On 15 Sep 2019, Winfield Hill wrote:

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals..pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.

Fun. I helped Tom Kelly start Imago, the tomographic atom
probe outfit which was eventually acquired by Cameca.
It was fun, I got named on a patent, and spent a lot of
money on airline tickets.

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

We get to play with a lot of fun stuff, without spending a decade or
so doing the undergrad/grad/PhD/post-doc thing, working on one thing.

John Larkin does enjoy being Mr. Superficial. His business model seems to involve him being asked to solve little bitty well-defined problems that have been defined for him by other people. He seems to have built up a stock of potential solutions which he can tweak to fit in a week or two.

--
Bill Sloman, Sydney

 

[Bill Sloman]

On Tuesday, September 17, 2019 at 6:26:27 AM UTC+10, John Larkin wrote:

On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE



I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

Review of Scientific Instruments makes this obvious from time to time. I've published five comments there making just this point - not only were the papers I was commenting on poor, but the people who had reviewed them for publication hadn't noticed.

The British equivalent - Measurement Science and Technology (which started off as the Journal of Scientific Instruments in 1924, a bit before the American equivalent) isn't anything like as bad, so it may just be American physicists.

Win started doing a Ph.D. in chemical physics - I finished one in physical chemistry - so it may just be American physicists who aren't too good with electronics. The delusion that electronics is just applied physics may a cultural problem.

--
Bill Sloman, Sydney

 

[Tom Gardner]

On 16/09/19 21:26, John Larkin wrote:

On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE



I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.