In the summer of 2003 I witnessed a very similar technology at a joint ISA-ESA-IEEE conference in Arkansas. The presentation was about how to carry liquids(a droplet) into a disposable IC that was going to be designed to analyze blood...they called it a DOC (doctor on a chip).
If my memory serves me correctly, not only did you have to have the spacing between the parallel traces exact and use high voltage, but the key was the frequency of the high voltage. The liquid droplets were like the insulators in a capacitor, the drive circuitry had an inductor in it, and at the resonant frequency the impedance of the liquid droplet was minimum, but IIRC this resonant frequency was superimposed on top of a HVDC pontential.
Basically the parallel traces were like the rails of a rail gun and the liquid droplet was like the projectile, and the demonstrator was able to move the liquid droplet around the PCB in between the parallel traces. Then the demonstrator went to show a huge grid design that would properly mix drugs using this technology, so you could have a DOC and POC (pharmacist on a chip).
The key point that the demonstrator made was that the moving action of the liquid droplet was not due to lorentz force or EM, but it was due to an electrostatic force.
Cheers,
Daniel
--- In Homebrew_PCBs@yahoogroups.com, "javaguy11111" <javaguy11111@...> wrote:
>
> --- In Homebrew_PCBs@yahoogroups.com, "jc805sb" <jc805sb@> wrote:
> >
> > --- In Homebrew_PCBs@yahoogroups.com, "javaguy11111" <javaguy11111@> wrote:
> > >
> > > Are you trying to mount MEMs devices on a pcb or using a pcb for making MEMs devices?
> > >
> >
> > I am etching copper patterns which operate as the MEMS
> > (the field calls it MEMS although there's nothing mechanical).
> > I have pictures on my blog here,
> > http://88proof.com/synthetic_biology/blog/archives/280
> >
> > The pictures show pretty poor etch results which
> > I am trying to improve using the best SMT techniques first.
> > Pad size/spacing is 1mm x 1mm with 0.125mm gap, or smaller!
> >
> > Other researchers in the field have made similar MEMS
> > on flexi boards. I can list some interesting articles
> > if interested. These boards move liquid droplets across
> > surfaces (even vertical surfaces). Though this requires
> > maybe >+1000V.
> >
> > Something tangentially interesting, some researchers used
> > an "aborted etch" method with multiple dips in etch and
> > multiple mask steps, to make copper traces of different
> > heights. Not useful for standard PCB however they were
> > able to use it as MEMS for nanoparticle separation.
> > They used ferric chloride as the etchant and found it
> > to be a linear etch, so the copper "steps" could be
> > precisely made. These steps were 10um to 50um or
> > something.
> >
> >
>
> I have some hopes of doing some homebrew MEMs experimentation. I am just getting back into board building and starting to do some work with photoresist. Once I get my technique refined, I will probably jump into a little MEMs experimentation.
>
> I did try a little electrowetting experimentation a year of so ago when I first heard about it. Nothing too sophisticated, just tried to verify the concept. Unfortunately it did not really work for me.
>
> I have often thought of starting a homebrew MEMs/microfluidics group similar to this group, but I really would not have the time to maintain it.
>