Question about "homemade" LEDs for Medical Use

Question about \"homemade\" LEDs for Medical Use

Hey all,
I'm a medical researcher working for a Canadian hospital, and I was hoping that I could get some help from the group's collective expertise. I am attempting to construct a camera system that tracks the location of LED markers during surgery. I've been going crazy trying to find a decent LED to use in the markers that satisfies the following criteria:

-Has to be peak wavelength around 630nm give or take 10nm
-Has to have a small enough current/voltage to run off of a couple of dry cells, probably watch batteries
-Has to be "small enough" to be unobtrusive during surgery, preferably smaller than a dime
-Has to have a fairly wide viewing angle (basically the wider the better, preferably over 50 degrees)
-Has to be BRIGHT! I've tried LEDs as bright as 1000mcd and they're still far too dim. Basically the LED needs to have a visible glow from about 4 feet away (the distance to the cameras). I'm still waiting for my 12000mcd LEDs to arrive so hopefully they'll be bright enough, but in this case the better is brighter.

So that's my difficult task. Does anyone feel like tackling a biomedical engineering dilemma? I'm looking for any ideas for an LED that might be appropriate, and where I might find them? Any help would be very much appreciated.

Thanks guys,
Ryan Janssen

Re: Question about \"homemade\" LEDs for Medical Use

Might want to check out an red/orange Luxeon (no optics) running off a single 123 cell. Would give you near 180 degree light for hours. Or get a Photon or Innova microlight and try sanding the lens to diffuse the light to see if that's bright enough.

Can I ask how is the camera going to track the LED? Sounds really interesting.

Re: Question about \"homemade\" LEDs for Medical Use

[ QUOTE ]
RyanJ said:
Hey all,
I'm a medical researcher working for a Canadian hospital, and I was hoping that I could get some help from the group's collective expertise. I am attempting to construct a camera system that tracks the location of LED markers during surgery. I've been going crazy trying to find a decent LED to use in the markers that satisfies the following criteria:

-Has to be peak wavelength around 630nm give or take 10nm
-Has to have a small enough current/voltage to run off of a couple of dry cells, probably watch batteries
-Has to be "small enough" to be unobtrusive during surgery, preferably smaller than a dime
-Has to have a fairly wide viewing angle (basically the wider the better, preferably over 50 degrees)
-Has to be BRIGHT! I've tried LEDs as bright as 1000mcd and they're still far too dim. Basically the LED needs to have a visible glow from about 4 feet away (the distance to the cameras). I'm still waiting for my 12000mcd LEDs to arrive so hopefully they'll be bright enough, but in this case the better is brighter.

So that's my difficult task. Does anyone feel like tackling a biomedical engineering dilemma? I'm looking for any ideas for an LED that might be appropriate, and where I might find them? Any help would be very much appreciated.

Thanks guys,
Ryan Janssen

[/ QUOTE ]
4 feet? Even a 100 mcd light should be very visible if you're looking directly at it. Or do you mean that you want the LED to be illuminating something that's 4 feet away? (When you mention marker LEDs, it makes it sound like you just want the LED to appear as a point source on the camera.)

If you just want the emitter itself to be visible when someone (or the camera) is looking directly at it, get some surface-mount LEDs. They don't get any smaller or wide-angle, AND they have no optics so they're an extremely small point source which should improve accuracy for your camera system.

If you need it to actually illuminate something - Go for a bare Luxeon.

Re: Question about \"homemade\" LEDs for Medical Use

[ QUOTE ]
InTheDark said:
Can I ask how is the camera going to track the LED? Sounds really interesting.

[/ QUOTE ]

Its actually going to be the same system used in making motion-captured movies and video games. We have a group of cameras that capture red light and triangulate it stereoscopically, then map the markers' 3d motions in real time.
It'll be pretty slick if we can get it to work under the bright background lights of the OR - my biggest concern is that they'll be drowned out in comparison to the bright spotlights. I'll make sure to order each one of these suggestions and give them a lab test, and see which one works the best. You guys have ben very helpful - thanks again for the expert opinions!

Re: Question about \"homemade\" LEDs for Medical Use

Look to the bottom quarter of the page at the magnetic "body lights". These may be just what you're looking for. They ARE bright.

Re: Question about \"homemade\" LEDs for Medical Use

If you need a red Luxeon, I happen to have one laying around, but I don't think it's in the right wavelength range for your camera. You can probably find all the wavelength info on the lumileds site. PM if you need it.