Doom playing on a pregnancy test

I mean, if it works it works. All these “cheap paper tests” are doing is reacting to specific chemical signature - but it’s cheap and accurate.

I would imagine replicating this with wholly solid state instrumentation would be incredibly expensive by comparison versus a simple photodiode check.

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Do they even do ‘wholly solid state’ for something like this?

It looks like there are a number of people(here’s one, it cites some others) poking at using other-than-optical inspection of the outcome of the usual lateral flow immunoassay, exploiting the electrical properties of the metal nanoparticles the antibodies are bound to, which looks higher tech than just wrapping the optical sensor around a test strip and may have advantages in terms of accuracy; but is undeniably still just leaning on the antibodies and capillary flow behavior to do the actual work.

If you wanted to really go all out in that direction you could probably make it look good; replace the functional-but-banal fiber pad with some cool MEMS microfluidic arrangement and monitor the movement of the metal particles with a really, really fine-grained network of resistive or capacitive elements fabricated doped into the MEMS structure; much scientific, such laboratory-on-a-chip, wow; but you’d still be making the antibodies do the actual work.

Does anyone know if there are viable options for semiconductor chemical sensors; or is that straight into “yeah, you want a tricorder, yes, we all sympathize; no, we can’t help you” territory?

Now play “Skyrim”…

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Yes, all of this is true. However he does replace the processor and battery and pcb and memory with an equivalent circuit. The display was not useable, but he seems to have found another one that works, and is driving it with 4 cables like the original. The general purpose LCD is probably cheaper than the special “not pregnant” display, and takes more programming to drive. The pee sensors were not needed, but a keyboard was.

I am happy he has proved his point. He shows the computer power in the pregnancy test could play the same game I remember playing on a Sun workstation in the 90’s, using reasonable substitutions. He could probably re-use the original processor and fit it in the original case if he was prepared to do some hairy surface mounting, but why bother?

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What’s really ingenious about the device is that it turns itself on when pee connects two electrodes on either side of the “analogue” stripe.

But someone else’s began, obviously. Congratulations!


Glucometers have a base unit and one uses test strips to make the test, but the LC dis bigger, have more memory and normally an rs-232/IrdA/USB/Bluetooth interface to download the dat to a computer and make analysis, but of course a glucose test is a regular thing and has a more complex setup to compensate errors.
This looks a simple optical comparator and a timer, and a pregnancy test isn’t a lifelong thing. But anyway having a strip and an instrument to measure it should be cheaper anyway.

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Based on the units I’ve seen, you’re right - a glucometer would’ve supported more of the game.

After only three years as a diabetic, my mother had about six of these among her effects. What jumped out at me wasn’t the differing claims about accuracy, but the difference in the test strips (with limited to no compatibility across multiple meters). With the extra waste because of that, along with the cost of the strips themselves, that device would’ve supported even more Doom. :money_with_wings:


That could easily be solved with a reset button and a replaceable paper strip. Supply the test with one reader and a pack of strips. Put in a new strip, reset the reader, pee on the strip. Of course, then they wouldn’t sell as many. That tells me the chips must be even cheaper than I thought. Otherwise they could make money using the same business model as diabetic test strips.


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