Anyone else seen the recent "Water Light Graffiti" project news coverage, for an installation in France recently?

This is *very cool*.

Do a search for "Water Light Graffiti" and you'll see lots of entries, sparing me wondering if a link I post is against policy.

So, I have a question, if anyone has been able to discern from the various videos, French or not, just how the circuitry is laid out such that the LED's light up when water is provided in the vicinity. I'm hearing impaired, so I can't quite pick out from the videos how he does it.

Anyone?

 

The one with grinding the tops off LEDs at the start?
There wasn't any audio description on the few I clicked, just music.

 

This is the artist's prototyping descriptive video in French.

http://www.youtube.com/watch?v=Ch-gYF1v3ls&feature=youtube_gdata_player

This is Hackaday's version with English translations in the comments.

http://hackaday.com/2012/08/12/painting-a-wall-with-light-using-water-as-ink/#comment-732118

The concept is simple. It uses close proximity contacts that are bridged by water to complete the ground connection. The shape and size of the contacts are engineered to hold a water bridge in a stable position for as long as possible.

 

The concept is simple. It uses close proximity contacts that are bridged by water to complete the ground connection. The shape and size of the contacts are engineered to hold a water bridge in a stable position for as long as possible.

This is the part I was trying to figure out - I can't quite pick it out from the video nor have I found some static images with more detail.

My closest guess is that there's a pair of 'rings' around the LEDs, perhaps as simple as traces on the PCB? Then the water can bridge the gap, and there's enough contact area so the amount of water would give some control to the brightness.

Any which way, a very creative art installation, if you ask me. Too Cool!

 

My closest guess is that there's a pair of 'rings' around the LEDs, perhaps as simple as traces on the PCB? Then the water can bridge the gap, and there's enough contact area so the amount of water would give some control to the brightness.

In retrospect I guess the first video (which I hadn't had access to from where I was working yesterday) does show pretty clearly how it works.

I imagine copper trace is probably the best way to accomplish this in a reasonably do-able fabrication method, but my instinct would be to have stainless steel rings of different diameters surrounding the dome of the LED, with traces running to the back for soldering purposes. The rings would be half-embedded in the substrate, raised enough to help support water droplets from sliding down the board, but not so high that they would tend to wipe off with repeated contact.

I suspect this would be difficult to do without some high-end fabrication work, but I have no experience in such matters.

 

Links are allowed, if they are not commercial or sexual in nature. New members may run afoul of the forums auto moderation feature, but there isn't much we can do about that.

 

This gives new meaning to the term "Water Boarding"