LED photomodulation device for biology project

Hi there,

For those of you who don't know, NASA studies have shown that light emitted from LED's at specific wavelengths are capable of stimulating and speeding the wound healing process in animal and human tissue. The technology has exciting applications in other areas too, namely; pain relief, dermatology and cancer treatment.

I've decided to assemble such a device for my school biology project.

For flexibility, the device should should have three detachable heads:
- one that irradiates between approx. 550nm and 650nm (peak 600/610 nm)
- one that irradiates between approx. 650nm and 750nm (peak 690/700 nm)
- one that irradiates between approx. 750nm and 900nm

Must output a minimum power density of 60 mW/cm2 or as powerful as the super-luminus LEDs will go
Light source must produce an efficient collimated beam to concentrate energy within a 1-10 cm2 area (depending on cost)
LED driver module must have the ability to output a continuos beam

Nice to have features:

The LED driver module should have the ability to output strobed pulses
- adjustable pulse rate of 1 hz - approx. 100hz
- pulse width of 1 - 4 milliseconds

Being self-confessed electronics twit, I would like to use off-the-self components as far possible i.e. purchase the driver as a distinct unit. As far as,I've heard the Lumiled Luxeon LED's are the most powerful ones on the market and they are available in multiple colors, emitting light in defined wavelengths.

Do you have any suggestions on what component I could purchase to achieve the above within a limited budget. So far I have been unable to find a driver to drive the Lumileds which have a strobe capability.

Any ideas would be much appreciated

Thanks so much

monsterbeam

monsterbeam

That is an interesting project! As soon as the New Years Eve hangovers wear off, I am certain that the many wizards in this forum will give you more than ample ideas on how to do this.

Good Luck! /ubbthreads/images/graemlins/party.gif

Hopefully the more tech savy here can help you. I am particularly interested in the procedure.

What exactly is your project. What are you trying to prove or achieve.

I have been following the news on the healing properties of leds for some time. I am particularly interested in the research done by Harry Whelan at the UW Milwaukee. His research was on the regeneration of damaged retina's in mice. Having a degenerative retinal disease that is slowly blinding me, I am trying to find out if this could be a possible treatment.

Cool project, I'm up for it but think you might want to do a bit of looking into what can be done with currently available devices. I suggest:

Don's LED types

as a starting point.

The optics will also take some thought, as will the doseage levels you're asking for. You may have to resort to lower levels for longer times?

I can easily sort out the electronics for you.

Anyway, I'll help you cobble something together (once you sort it out a bit more), but don't haunt this forum often, send me a PM?

Doug Owen

Totally out of the blue and with no sound reasoning behind it, but have you considered laser diodes instead of leds? I don't know, but maybe they can get you the power levels and maybe the frequencies that you need. Like I said, don't know a thing about them, other than the baldness-brush I mentioned in the SAD thread claims to use laser diodes instead of leds - I figured they were claiming functionality based on the same studies you are looking at.

Yeah, I've thought about it but for reasons explained below apparently LEDs are more suited for biostimulation applications (and much safer to handle which is a big plus!)

"LEDs are similar to laser diodes in as much as they have the bio effects, but they differ in the way the light energy is delivered. A significant difference between LEDs and laser diodes is the power output. The peak power putput of an LED is measured in milliwatts, while a laser diode is measured in watts. However, this difference, when considered alone is misleading, since the most critical factor, that determines the amount of light energy delivered is the duty cycle of each diode.
An LED usually has a 50% duty cycle. That is, the LED Pulse is "ON" for 0.5 seconds and "OFF" for 0.5 seconds versus the 200/1,000,000,000 (200 billionths) of a second burst from a Laser Diode at 1 Hertz/pulse per second. Moreover, an LED is "on" 50% of the time and "off" 50% of the time, regardless of what Frequency/Pulses per second setting is used. On the contrary, the Laser Diode is "on" for 0.000000000005 of a second and "off" for 0.999999999995 of a second. In short, the LEDs emit more than 33% light energy, than a comparable laser diode, because of the substantially longer duty cycle, eventhough the peak power output is less.
LEDs do not deliver enough power to damage cellular tissue, but they do deliver enough light energy to stimulate a response. With a low peak power output, but high duty cycle, the LEDs provide a much gentler delivery of light energy.
Moreover, LEDs do not produce coherent or collimated Light, but they do generate a monochromatic (single-wavelength) light beam, which a laser diode also does. Non-collimation and the wide-angle diffusion of the LED confers upon it a greater ease of application, since light emissions are thereby able to penetrate a broader surface area."

[ QUOTE ]
monsterbeam said:
The LED driver module should have the ability to output strobed pulses
- adjustable pulse rate of 1 hz - approx. 100hz
- pulse width of 1 - 4 milliseconds


[/ QUOTE ]
This could probably be done with a couple of 555 timer ICs. I think they're capable of sourcing or sinking up to 300ma without an external power transistor, which gets you into the Luxeon range.

For a quick and dirty driver, you could hack one of those blinking LED bicycle-lights. /ubbthreads/images/graemlins/grin.gif

[ QUOTE ]
monsterbeam said:
Yeah, I've thought about it but for reasons explained below apparently LEDs are more suited for biostimulation applications (and much safer to handle which is a big plus!)

"LEDs are similar to laser diodes in as much as they have the bio effects, but they differ in the way the light energy is delivered. A significant difference between LEDs and laser diodes is the power output. The peak power putput of an LED is measured in milliwatts, while a laser diode is measured in watts...."

[/ QUOTE ]

This is not necessarily true. There are any number of few miliwatt LASER diodes, in fact I suspect they easily outnumber the Watt and larger ones many hundreds of times over (there's a lot of LASER pointers out there.......). CW units like the pointers no doubt outnumber the pulsed ones. They have been studied, a web search will find some 'evidence' on their behalf.

An excellent opportunity exists, IMO, with low power LASER diodes that aren't columnated, that is you can use a beam of all the same color (monochromatic), in phase (coherent) but not a 'dangerous' pinpoint beam. I don't think they should be dismissed.

The best call seems to be options to change LEDs as well as the drive levels (total output) and wave form.

I'm still willing to take part.....

Doug Owen

Doug, thanks for your offer to help. I sent you a PM. Did you receive it?

I remember (something in New Scientist within the past 3 months) mention that laser light, but not LED light, can actually sort small objects -- they move to the 'dark' areas and away from the 'light' areas that we see as the speckled effect from laser light. The article suggested that components within cells may also be moved around by this effect, that was where the research was going next. And it mentioned that tinnitus, among other things, is being treated with red laser illumination.

I assume that's using something low powered enough that the laser beam doesn't shine in one ear and out the other -- although, when the ringing in the ears gets really bad, that'd be tempting. So I hope this stuff works out.