At home fabrication of micron scale microfluidics

[Peter Shankles]

Hello all,

I'm new to the DIYbio community and need your perspective on something. 

I'm working on a project that would make microfluidics available to use at home. Because I'm working on this at a national lab, I can't give too many specifics at this time. With that being said our setup would include software for designing devices and creating a master mold for soft lithography. The resolution would be on the order of 100 um, and the fabrication time would be a couple of hours. 

What I want to know is:

  What types of features and designs would be most important to include?

  How much would you be willing to pay for this functionality (software will be open source, but there is hardware as well)?

  What would you be most interested in using microfluidics for?

  Anything else you can think of. I would appreciate any input you have.

Thanks for your time,

Peter

[Bryan Bishop]

On Thu, Feb 26, 2015 at 2:32 PM, Peter Shankles <pshan...@gmail.com> wrote:

  How much would you be willing to pay for this functionality (software will be open source, but there is hardware as well)?

So the hardware would include a spin coater? You haven't given me much detail to work from, here.

- Bryan
http://heybryan.org/
1 512 203 0507

[John Griessen]

On 02/26/2015 02:32 PM, Peter Shankles wrote:
> What I want to know is:
> What types of features and designs would be most important to include?

Ability to design chambers in between thin flexible layers -- so they could become pumps...
Pressure connections, (5 bar or whatever your process can do), out the top,
(normal to the plane), of planar microfluidic assy.

> How much would you be willing to pay for this functionality (software will be open source, but there is hardware as well)?

$500+

> What would you be most interested in using microfluidics for?

Flow cytometry on the cheap.

> Anything else you can think of. I would appreciate any input you have.

Does this avail existing flex circuit fabbing tech in polyamide?

John Griessen

[scoc...@gmail.com]

Would this beat shrinky dink microfluidics? I've managed to make features using shrink sheets printed using a standard toner printer and pdms at around 100-150um and tested with plant protoplasts. With soft lithography, would you use SU-8 or some other material type? How will your software compare to other free CAD programs like draftsight? Will it be photolithography for the master mold production?

Price I would personally pay depends on functionality vs cost. If you can really deliver a simple system (or any system) for production that isn't as finicky as shrinkydinks I'd pay decently for it. It would dave so much time and wasted effort. So much time spent watching templates warp in the toaster oven and whatnot. Also, how will you overcome the hydrophobicity of pdms? I use a corona arch wand but that's not cheap and the microwave method needs a good two stage vacuum pump (also not cheap) so I'm super interested in alternatives.

If the end material is glass or pmma (acrylic) that would be great too. Any thoughts on chip connection and reusability?

Sebastian S. Cocioba
CEO & Founder
New York Botanics, LLC
Plant Biotech R&D

---

From: Peter Shankles
Sent: ‎2/‎27/‎2015 8:42 AM
To: diy...@googlegroups.com
Subject: [DIYbio] At home fabrication of micron scale microfluidics

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[Peter Shankles]

Thus far we have been casting PDMS in thicker slabs. I'll look into possibly adapting it to use with a spinner. Would this be for control valves?

-Peter

[Nathan McCorkle]

On Fri, Feb 27, 2015 at 8:59 AM, <scoc...@gmail.com> wrote:
> Would this beat shrinky dink microfluidics? I've managed to make features
> using shrink sheets printed using a standard toner printer and pdms at
> around 100-150um

That was my first thought.... the scale is quite large when you start
thinking of doing cellular operations that are anything more than an
incubation chamber.

[GO]

Can you make lego kind of system? For example, make separate components: channels, valves, chambers with different functions and then sell those? The purpose is that anyone can then assemble a desired system easily since PDMS can be bonded. Otherwise your resolution is my problem and also hydrophobicity of pdms. 

Legos can be easier to sell and manufacture too. I would buy some components for ~$100 but for <20 microns resolution. The purpose would be to embed side electrodes for detection and play with that. 

[scoc...@gmail.com]

I'm my attempts at making modular units, transfer of discrete liquid packets or even continual flow  is tough when you need to move from one chip to another. Alignment, pressure tolerance, hydrophobicity, etc all play a role in getting things up and through.

I tried using tubes as connections and found that slurping and sputtering happens. Aligning chips is a whole other can of grief if you want to make continual modular chips. The Lego based chips seen here:

http://www.redorbit.com/news/science/1113239467/lego-inspired-microfluidics-092214/

Need a very high degree of hole punch, die cutting and overall "machining" to mate well. ShrinkChips are variable during shrink and can lead to small defects. Connecting "millifluidic" chips involving >500um features but at super low volume pressure is an issue. If you don't have a coronal treater or rig a microwave to oxidize the pdms, pressure becomes even more of an issue. I've been spattered with food coloring trying to get a simple 100um T junction working...soooo....yeah. I'm very very interested in alternatives but if the kit is SU-8 at home, I'm out. Its so expensive and the overhead to do it well may be a bit much for the first time lab builder. Just my 2¢...

Sebastian S. Cocioba
CEO & Founder
New York Botanics, LLC
Plant Biotech R&D

---

From: GO
Sent: ‎2/‎27/‎2015 1:22 PM
To: diy...@googlegroups.com
Subject: [DIYbio] Re: At home fabrication of micron scale microfluidics

Can you make lego kind of system? For example, make separate components: channels, valves, chambers with different functions and then sell those? The purpose is that anyone can then assemble a desired system easily since PDMS can be bonded. Otherwise your resolution is my problem and also hydrophobicity of pdms. 

Legos can be easier to sell and manufacture too. I would buy some components for ~$100 but for <20 microns resolution. The purpose would be to embed side electrodes for detection and play with that. 

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[Simon Quellen Field]

It would seem to me that the main problem in transferring liquid from one block to another is basically the problem of pushing on a rope. The liquid will try to go everywhere except where you want it.

The alternative that suggests itself is to pull the liquid from one block to another using a relative vacuum. Now the liquid wants to go only where you want it to go.

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[John Griessen]

On 02/27/2015 05:29 PM, Simon Quellen Field wrote:
> The alternative that suggests itself is to pull the liquid from one block to another using a relative vacuum. Now the liquid wants
> to go only where you want it to go.

because vacuum makes contact seals seal harder, and pressure makes them leak.

[scoc...@gmail.com]

This is true, only issue there was when using a syringe to pull from chip to chip, the line would sputter and induce air pockets on top of very swift changes in fluid flow once it gets past the bottleneck that is the chip. There is a lot of resistance since the channel features are so small that manual pull is to quick. Need a syringe pump in reverse that pulls slowly.

Like filling a syringe quickly with liquid through a very small needle, it bucks back until the liquid meets the top of the plunger (vacuum until pressure equalizes) so either way fine, non-manual control would be ideal. Backpressure is too high for standard cheap-o eBay peristaltic pumps in either direction. Basically its analogous to electronic theory...small channel, high resistance. Syringe acts as a voltage source trying to pull more than the channel can deliver so its either slow or the channels (or chip) fails structurally.

For the few moments when the pdms is perfectly bonded via coronal arch discharge and everything is aligned properly, I did get some plant protoplasts stuck in a T junction for a while while flowing media through. Its possible, just really really finicky.

On my laundry list of experiments to run, I'd like to do some data gathering on the characteristics of shrinky dink plastic sheets, temperature, shrink rate (~63%), etc to see if its a viable material for making multiple fairly-identical chips. Basically a datasheet characterizing the material within the scope of microfluidics. May prove useful to people trying to start working with microfluidics.

Sebastian S. Cocioba
CEO & Founder
New York Botanics, LLC
Plant Biotech R&D

---

From: John Griessen
Sent: ‎2/‎27/‎2015 6:46 PM
To: diy...@googlegroups.com
Subject: Re: [DIYbio] Re: At home fabrication of micron scale microfluidics

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[Dieter]

If you don't need microvalves, there is some interesting work being done with low cost laminate microfluidics. The general idea is to laminate together transparencies printed in a laser printer. The toner can act as thermally set glue and thin channels, and thicker channels can be defined via laser cutting. This is low cost, requires reasonably cheap equipment, and uses no wet processes.

 http://diyhpl.us/~bryan/papers2/microfluidics/A%20Dry%20Process%20for%20Production%20of%20Microfluidic%20Devices%20Based%20on%20the%20Lamination%20of%20Laser-Printed%20Polyester%20Films.pdf (Bryan Bishop strikes again)

[Otto Heringer]

I always wanted to print a mold for PDMS microfluidic chips using a "form 1" 3D printer (that one who got funded on kickstarter). They say that it have 10 microns of resolution on Z axis.

When I was about to try it on a local FAB Lab, the printer got broke! If it was worked out, I would suggest to consider a 3D printer for the molds.

I think its about time for people go for digital fabrication methods on microfluidics.

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[Nathan McCorkle]

My co-worker has a formlabs printer, it seems pretty decent... The Z
direction sounds good, but I imagine it could be obviated by the use
of a spin-coater. They say their minimum feature size if 300microns...
I was thinking about this recently actually and ran into the
laserShark galvanometer controller. I think the main thing that would
need to change for great microfluidics with this type of setup is
really just the per-bit voltage-interval... i.e. if the DAC on the
galvanometer controller is 16-bits spanning the form1 build dimensions
of "125 × 125 × 165 mm"... then the range of millimeters spanned needs
decreased. If it's a linear decrease, then if I wanted a max
microfluidic X/Y dimension of 30mm, that's 125/30==4.166 then
300/4.166==72 microns resolution. Maybe their DAC is not enough bits,
or maybe this technique is not optimal, I don't know. It could simply
be that the long path that the beam passes takes, leaving the laser,
bouncing off the galvos, is just too much from a beam divergence
standpoint. To get a small spot size with such focal distances, I
think the laser would need a pretty big beam expander before lensing
onto the first galvo.

> https://groups.google.com/d/msgid/diybio/CAB%3DC6ZJjwZrt0LUVdhQQTA-s69adh9UbFjmVGLnH0MvSs2Zvnw%40mail.gmail.com.

>
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-Nathan

[Jonathan Cline]

On Friday, February 27, 2015 at 5:42:56 AM UTC-8, Peter Shankles wrote:

 

What I want to know is:

  What types of features and designs would be most important to include?

 

 

I believe there is a better way to approach your marketing survey.  Find a protocol that needs to be done DIY.  Then create a microfluidics solution which fits that protocol.  Repeat with three different protocols.  Then you have something interesting.  For example, Genomikon is a kit using very good DIY synbio protocol.  Now just make a microfluidics version.  This solves multiple problems.  The reagents are expensive, and microfluidics allows this cost to be significantly reduced per experiment run, by reducing the volume of liquid used.  The microfluidics version would also remove human error in liquid handling, reducing waste (thus also total cost per experiment) and schedule delay.

The most important feature of your product however is very simply going to be better yields.


## Jonathan Cline
## jcl...@ieee.org
## Mobile: +1-805-617-0223
########################

[Gordana Ostojic]

Not sure it works but a couple of ideas:

1.to reduce the pump pressure of your pump, can you make a T with tubing so one line has much smaller resistance than your chip?

2. Alignment can be a tedious problem, maybe use microscope and a micrometer stage ( http://www.thorlabs.com/navigation.cfm?guide_id=2 ). One chip fixed, other has a 3D control. I used the one on the microscope so I can see and position at the same time.

Yup, it is tricky either way. How did you bind pdms?

[Bion Howard]

Are you talking about stereolithography?

[Nathan McCorkle]

On Mar 1, 2015 1:35 PM, "Bion Howard" <fleshea...@gmail.com> wrote:
>
> Are you talking about stereolithography?
>

Most likely if you want fine features of <~25 microns. Photoresist is cheap though, exposing it is the trick needing a good solution.

[Simon Quellen Field]

I used to do lost-wax metal casting. My wife still does (using bronze).

A similar approach seems like it would lend itself to microfluidics.

Melt some sugar, and pull it into thin threads.

Build your device by bending and connecting these threads to form the chambers and tubes you wish to have in the final device.

Embed the sugar threads in a casting medium such as acrylic resin.

When the resin has hardened, boil the device in water, and flush hot water through the tubes and chambers until all the sugar has been removed.

The process can be made easier by soaking silk or dacron thread in the melted sugar and using that to form the main channel. As the sugar dissolves, you can then pull the thread through the device, speeding the removal of the sugar.

The thread can also serve as an alignment mechanism between two pre-manufactured blocks. Apply a vacuum to one end of a block, and insert the thread into the other end. The thread will be sucked through the device and come out the other end. feed that end into the second device, and apply suction to the other end of that. Now you have two devices connected by a thread that runs through both of them. The chamber with the thread will automatically align the two devices. Bond them together, then remove the thread.

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[John Griessen]

On 03/01/2015 04:36 PM, Simon Quellen Field wrote:
> I used to do lost-wax metal casting

Like your lost sugar casting idea. Sugar pulls like glass, so fine strands of
calibrated thickness can be made. Maybe a 3DP of some sort will do it in the most
calibrated way by being quick once the right diameter is pulled out of the sugar taffy
starting blob.

[John Griessen]

On 03/01/2015 04:36 PM, Simon Quellen Field wrote:

> Melt some sugar, and pull it into thin threads.
> Build your device by bending and connecting these threads to form the chambers and tubes you wish to have

The nature of sugar taffy is good for smooth flow. There would be much less turbulence than in any planar
photolith process defined digitally -- as in the blu-ray resin catalyzer-on-the-fly machines.

[John Griessen]

On 03/01/2015 04:36 PM, Simon Quellen Field wrote:

> Melt some sugar, and pull it into thin threads.
> Build your device by bending and connecting these threads to form the chambers and tubes you wish to have

It might even be possible to apply local focused heat when making a sugar thread connection to smooth the
mashed-together-mechanically-tees. You would not want so much heat that the sugar threads stick to a surface and
make half-rounds instead of circle cross section tubes...

[Peter Shankles]

On Sunday, March 1, 2015 at 2:54:32 PM UTC-5, Jonathan Cline wrote:

 

I believe there is a better way to approach your marketing survey.  Find a protocol that needs to be done DIY.  Then create a microfluidics solution which fits that protocol.  Repeat with three different protocols.  Then you have something interesting.  For example, Genomikon is a kit using very good DIY synbio protocol.  Now just make a microfluidics version.  This solves multiple problems.  The reagents are expensive, and microfluidics allows this cost to be significantly reduced per experiment run, by reducing the volume of liquid used.  The microfluidics version would also remove human error in liquid handling, reducing waste (thus also total cost per experiment) and schedule delay.

The most important feature of your product however is very simply going to be better yields.


## Jonathan Cline
## jcl...@ieee.org
## Mobile: +1-805-617-0223
########################

Thanks, I'll look into building around a few key protocols. 

We're doing work with a 3D printer to lay down features and cast PDMS over them. Right now you can design a device in CAD software, but then you can't control how the slicer software breaks up the print. We got a lot of channels not connecting because the print head will start and stop in the middle of a channel. The software we're making uses a list of features that the user can choose and combine in any pattern to make a chip. It writes a gcode file that can be sent to the printer. Once printed PDMS can be cast over the features and cured with the heated print bed. With the 3D printer we also have the ability to write channels in 3D and overlap channels. I attached a few photos of a chip we did to show this.

Once the gcode file is written the chip can be rewritten in less than a minute. This could theoretically work with any other casting material.

On the topic of lego type devices. We could make larger sets that can be connected in the software and printed as a single device. This would eliminate the risk of leaking between devices and such.

[Otto Heringer]

Aha! 3D printers! Are you using melted plastic deposition or something like the form I printer!?

About the sugar idea: will it not dissolve within the use!? Not even a little?

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[Nathan McCorkle]

On Sun, Mar 1, 2015 at 3:26 PM, John Griessen <jo...@industromatic.com> wrote:
> On 03/01/2015 04:36 PM, Simon Quellen Field wrote:
>>
>> I used to do lost-wax metal casting
>
>
> Like your lost sugar casting idea.

> Maybe a 3DP of some sort will do it

That is (almost?) exactly what Jordan Miller did... he used to post on
here more before he became a professor.

http://www.upenn.edu/spotlights/rep-rap-3d-printing-blood-vessel-networks

http://blog.reprap.org/2012/07/on-challenge-of-3d-printing-sugar-for.html

[Simon Quellen Field]

The idea is to dissolve the sugar away before the device is used.

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[John Griessen]

On 03/01/2015 08:35 PM, Peter Shankles wrote:
> With the 3D printer we also have the ability to write channels in 3D and overlap channels. I attached a few photos of a chip we
> did to show this.

Looks nice. You can get down to 100 micron channel size now? Cured PDMS can probably hold in 3 atmospheres of
pressure for moving fluids around... and you can control channel width for higher volume/lower-drag wherever
you can afford the extra volume. Looks like PDMS gives low amounts of air pockets compared to ordinary
rep-rap extruded plastic filament -- is your printer squirt driven by syringe, piezo, positive displacement pump
near the print nozzle?

Is anyone taking on the gcode problem of discontinuities yet?

[Brian Degger]

The other end, really big 3d objects using fused sugar layers

http://www.evilmadscientist.com/2007/solid-freeform-fabrication-diy-on-the-cheap-and-made-of-pure-sugar/ 

In February we gave a sneak preview of our project to construct a home-built three dimensional fabricator. Our design goals were (1) a low cost design leveraging recycled components (2) large printable volume emphasized over high resolution, and (3) ability to use low-cost printing media including granulated sugar. We are extremely pleased to be able to report that it has been a success: Our three dimensional fabricator is now fully operational and we have used it to print several large, low-resolution, objects out of pure sugar.

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[Otto Heringer]

Omg, this sugar stuff is so awesome! Thanks for sharing!
By the way, have you already seen this open hardware for microfluidics control!? This is another cool DIY thing to have on a lab that plans go on microfluidics.
http://microfluidics.utoronto.ca/dropbot/

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[Brian Degger]

Otto,

for a simple experiment with electrowetting (what the dropbot uses) 

 

https://www.youtube.com/watch?v=eD0h2jBZXCI

[Simple experiment on electoro wetting effect using a ribbon cable, oil ink and high voltage. DIY Open Science by GaudiLabs.]

John Griessen,

There are many slicers, each do slightly differently, so some might not have those discontinuities.  

Have you tried previewing the gcode layer by layer with something like this ?

http://www.3dgeni.us/gCodeViewer/index.html

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[Peter Shankles]

I've been using the Repetier Host software. They have a layer by layer preview and a couple of built-in slicers. I'll have to look into some other slicers tho.

Thanks,

[Peter Shankles]

I think I may have deleted someone's post. I'm vary sorry, I didn't mean to. I was trying to fix a typo in my reply.

[Nathan McCorkle]

On Mon, Mar 2, 2015 at 4:55 PM, Peter Shankles <pshan...@gmail.com> wrote:
>I think I may have deleted someone's post. I'm vary sorry, I didn't mean to.

> was trying to fix a typo in my reply.

Are you an admin? I get these as email messages... so I can re-post if
you think you know which it was.