Not sure what would be the best chip to use in the following application

Okay, so, I live with my dad. He’s a mess and a entry-level pack rat. I’m the person who does the dishes. I don’t know what he does, but he plays around at the sink a lot. He clogs up the drain and then just leaves the sponge to stew in bacteria water. I really hate this. We used to get into arguments about it, but I just put a sign and for about 1 week the sponge was squeezed out and put outside of the sink. Well, I guess it’s true that you can’t teach a boomer-dog new tricks, cus it’s back to floating in disgusting water nearly all the time except for when I fish it out.

I want to find some kind of cheap RFID chips that I can secure in some way inside the damn sponges. It guess I can reuse the chip, but I’d rather have chips that are relatively disposable. Anyway, I want it where some kind of super bright LEDs flash and some extremely annoying siren goes off until the sponge is placed back in a certain spot.

I more or less know how to do all of this, except for what would be the best chip to use for this.

I could use a few ideas, lol. He’s going to think I’m nuts, but it’s so gross and I hate it so much!!

Hm you could probably do it with some HF glassies bough off Ali in packs of a hundred, an Arduino, an RFID shield, a buzzer, some LEDs and a 3d printed housing. Maybe some potting reisin given that it will be near water all the time. There are also sticker tags that are often also waterproof, but I don’t know how well these would resist wringing the sponge out.
I thing a ntag216 would do the trick, but could be wrong. Maybe others will chip in?


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I love the idea of a technical solution, but how about a cheap and easy alternative?

If you really wanted to go technical, I would be looking at UHF.
Let me know if you need a further point in the right direction…

Hmmm any particular reason for that?

Yeah I guess UHF is the wrong approach… we’re talking about placing an object on a known spot (chip in sponge, reader where you put it).

I honestly don’t know what the advantages and disadvantages of UHF are :sweat_smile:

This is funny and spiteful and I love it. You could use the xAC v2 and install it under the sink, and put the antenna either right up against the other side of the drain or cut a hole and have it sticking through with some silicone caulk to seal it. All you would need is cheap compatible glass tags from alibaba. The only issue is if the stainless steel from the sink will interfere with the signal. If it works just have the relay on the xAC turn on a bright LED light strip


Haha MOQ 1-5k per roll, 5-10 rolls

Hmm. For me it says MOQ 500 and $0.07-$0.25 per unit, so only $125 + $24 for a lifetime of clean sponges. I call that a win. You can also buy them in much smaller quantities on ebay for like $2 a piece

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Go for “laundry tags”… small, black abs plastic that can hold up to anything, and great range …


Passive or powered

In saying that, since you are talking about a sink full of water, the lower the frequency the better it transmits though water.
So 125kHz would also be a good option.

Personally HF would be further down my lists for testing.

You could look at Bluetooth, but based on 2.4GHZ the attenuation through water is not very good.
(Although I have used some Bluetooth diving and got about 1m range which would be enough for your use)

Laundry tags I know they make them in UHF and LF and I think they do HF but not 100% on that
Your antenna is a major part of the build and how you go about that.

What is the sink made of?

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Reminds me the Victoria Secret RFID tags.

Depending on your sponge, you could add a plastic tag that don’t mind to be wet.
An Arduino, Reader, Buzzer.
Sponge gets removed from in front of the reader and a countdown timer starts.
After some seconds the reader will check that the sponge has been returned to its place, if not BEEP BEEP BEEP BEEP.
You could aim to “train” your dad by making him get the sponge close to the reader every few seconds even before he finish using it, so he will get used to the motion of putting it back in its place.

But to be honest, the most probable thing that will happen is that he will disconnect the noisy shit or plain old smash it with a hammer until it shuts up.

UI vs UX

If he is not consciously against putting the sponge back in its place, you don’t need to be so “offensive” with a loud noise, a blinking LED indicator should be enough. Maybe a message?


Nice artwork Ryu, you clever little dude! :+1:t3:

What are “HF glassies”? I’m assuming HF is High Frequency, but what is “glassies”? Sounds like some kind of cool new drug, lol.

Yeah, or, honestly, I could make some kind of retractable tether like the ink pens at a bank.

I mostly want to go the technical route though to gain experience because the general idea of this translates to a ton of different things. Also, it’s a good excuse to learn about RFID, which although I know a little, still trips me up sometimes.

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While I do have plans to turn the entire house into some kind of futuristic automatic space habitat I really do not want to start drilling holes in things until the entire system has gone through a few revisions first.

With “glassie” I was refering to the x-series glass-encapsulated “pill”-shaped tag form factor, that is often implanted using an injector.

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Really like the way you made the unit there. He will definitely just put the sponge back as that is way easier and less effort than destroying it. Also, he will think it’s somewhat funny.

What kind of tag is that in the first picture?

Pretty sure that is a UHF tag