Bill, I actually posted the question, not David.

This is for microfluidics. I'm trying to get curved AND square
channels. It looks like I can't have these on the same layer, unless I
use FIB maybe, but then that limits production rates in the future
(when I'm not making just one device). The two channels are next to
each other and positioned perpendicular, when the square channel is
pressurized it cuts off flow in the curved channel.

http://www.kni.caltech.edu/foundry/graphics/msl-ex2.gif
http://www.stanford.edu/group/foundry/images/Microfluidic_valve_technology_clip_
image011.jpg

I'm going to use a DLP projector as a digital photomask, so inverting
the color is a simply photoshop operation. What's the functional
difference between positive and negative resist other than whether it
inhibits or activates hardening? Do only positive resists have glass
transition states?


On Fri, Sep 20, 2013 at 9:16 AM, Bill Moffat
 wrote:
> David not clear on your question. If you are trying to create a resist profile
that has vertical lines image reversal can do this.  Using the flood exposure it
is possible to go from a negative resist angle of 22 degrees, through vertical
to a positive 22 degrees in controllable stages. Contact me at YES for free
trials.  Bill Moffat 925 373 8353.
>
> Sent from my iPad
>
> On Sep 20, 2013, at 7:22 AM, "Nathan McCorkle"  wrote:
>
>> I'm working on microfluidics and think I can use PDMS castings
>> directly on my photoresist for square channels, but the resist looks
>> like swiss-cheese up close when it's defocused to create a curved
>> profile, so I think my only option is to pattern then isotropic etch,
>> ash/wash away resist, then cast with PDMS.
>>
>> Seems that HF based solutions are my only google hits...I've used HF
>> once or twice before and the local lab I plan on working in has HF
>> already, but I remember being pretty wary of the HF. I occasionally
>> bump or spill things, not /that/ often, but I'd rather play with safer
>> chems if possible. I guess driving my car might be more dangerous
>> statistically, but I feel there's a little more wiggle room in
>> something like driving!
>>
>> Anyway, any recommendations would be great. I don't have any process
>> setup yet so I'm flexible.
>>
>> --
>> -Nathan
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--
-Nathan
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

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