Modding Steripen Adventurer (optical) for surface disinfection
April 1, 2020 10:59 PM   Subscribe

I'm trying to turn my Steripen Adventurer UV water disinfecter into something I can use on surfaces for, well you can probably guess why. Problem is that this model uses an optical sensor to sense water and prevent it from turning on elsewhere. This means, unlike older models, I can't just short the probes. Any engineering types know of a way that I might be able to bypass the optical sensor to force the UV light to turn on? Could it be as simple as covering the sensor with something I might have around? No need to warn me about voiding my warranty, messing around with UV, or unproven efficacy, please. I'm a biomedical engineer, so I'm well aware of the risks! Thanks!
posted by beammeup4 to Technology (5 answers total) 1 user marked this as a favorite
The consensus seems to be that the type and intensity of UV required to kill the coronavirus is A) Not achievable with consumer-grade equipment and B) Harmful to human beings.

There are a number of commonly-available materials that will quickly knock out the virus, including alcohol solutions greater than 70%, dilute bleach*, and regular 3% hydrogen peroxide. You'd be better off going with one of those, since you would not have any assurance that your Steri-Pen was actually effective.

* Note that bleach as sold does expire (check the date on the bottle), and that solutions mixed for disinfection use are only good for 24 hours, per the linked site.
posted by Kirth Gerson at 4:36 AM on April 2, 2020 [6 favorites]

posted by gregoreo at 4:39 AM on April 2, 2020

Best answer: My naive guess, based on the photos, is that the small clear bulb is a photodiode or phototransitor and they're relying on the difference in indices of refraction between water and air varying the amount of UV light admitted across the environment-to-plastic interface to decide whether or not to stay turned on. Depending on which plastic is used in the part, this could either make the light dimmer or brighter, but it's probably brighter. I'd suggest trying a hollow aluminum foil tunnel connecting the bottom third of the light to the sensor to make the light brighter, followed by slightly opaque things (tissue paper?) placed in between them to make it dimmer.

If you pry off the plastic plate or otherwise open it up, you'll probably find two metal wires coming out of the clear plastic bulb and soldered to a circuit board. There's a 60% chance that either shorting them (with a metal paperclip) or opening them (by cutting one) will make the device turn on. Given the batteries in this thing, you're unlikely to hurt yourself, but destroying the device is a concern. If you feel like tearing the thing apart and taking closeup photos of the inside of the clear bulb and the circuit board it's attached to, we might have more to go on. But, that's a destructive choice.

(Personally, I wouldn't trust this to disinfect water, much less surfaces. A quick lit search raises every red flag that I associate with sketchy science. But, I'm definitely not an expert in this area.)
posted by eotvos at 7:59 AM on April 2, 2020 [1 favorite]

Response by poster: Thank you, Kirth, and gregoreo, for completely completely observing the last sentence in my request and proving thoroughly helpful answers...

In regards to the best answer, I'll give the light-blocking tunnel a shot, and if it doesn't work, I'll leave it at that. Not going to potentially destroy a device with those chances, especially given that the evidence behind UV-C killing coronavirus is still lacking.
posted by beammeup4 at 9:48 AM on April 2, 2020

I'm just going to ignore your last sentence not because I think your an idiot but rather for anyone else reading this and getting ideas. You can blind yourself doing this. You can blind your pets or children too.
posted by Pembquist at 10:22 AM on April 2, 2020 [7 favorites]

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