Smart Litter Box Sensor

If you have an indoor cat, you’re probably all too familiar with the litter box-changing process: You peek and sniff at the litter box, and if you encounter a grim sight or bad smell—it’s time to change the litter. Once you build your own smart litter box sensor, your cue becomes a blinking light and a text message. Much nicer, right?

Check out the video above to see it in action. And look below for some shots from the prototyping process.

1665_001_rtimg_4647_rtimg_4798_rtimg_4758_rtimg_4790_rtimg_478_rtimg_4786_rtimg_4795_rtrianna-chaz-2Want one? Find out how to make your own here!

Final Project Proposal: DIY Smart Litterbox

As adults, we have the right to only be responsible for our own poop. But when you own an indoor cat, you give up that right. Your cat’s poop  becomes your responsibility.

It’s never fun to find out that it’s time to change out the litter in your cat’s indoor bathroom (i.e. litter box). Smell is the key indicator, and who likes to sniff around for a bad smell?

Enter, the smart litter box sensor:


The sensor detects the excess ammonia gas emanating from an uncleaned litter box. In response, it has two outputs: it lights up two LEDs (behind each eye in the little kitty head), and it sends an SMS (text message) to the keepers of the litter box (i.e. the pet’s owner(s)/parent(s)).

I’ve already prototyped a non-texting version of this product:


< Sketch of wiring diagram for sensor, 2 LEDs and Arduino board


< Soldering/wiring process for sensor and LEDs


< 3D-printed enclosure for the sensor, LEDs and wires (it’s too small!)

And now it’s time to add the text-sending functionality to the equation. This will require:

  • A WiFi-capable circuitboard, like the Huzzah Feather (already purchased)
  • Getting my existing code to work on this new board (work in progress!)
  • Adding a text-sending functionality by parsing through how-to guides like these:
  • 3D modeling of a new container that fits my wiring and my new circuit board!


Litterbox Monitor: sensor prototyping

I’m developing a fume-activated litterbox monitor (i.e. “your cat’s box smells bad! time to clean it!”). I’ve devoted this first prototyping to achieving full functionality in my sensor in the breadboard phase. As you can see* in the video below, I have:

Here’s a clearer look at my breadboard wiring:


And here’s a glimpse into the process whereby I concocted a water-ammonia solution with roughly the same ammonia levels as cat urine:


Healthy cat urine is allegedly .05% ammonia, among other things. So I combined 2 liters of water with 1 milliliter of ammonia to simulate cat urine. However, this concoction was too mild to impact the gas sensor enough to create a spike in the serial output, so I ended up just doubling the “resting” threshold as my “stinky-enough” benchmark.

Here are my envisioned next steps:

  • Incorporate a smaller Arduino board for a sleeker profile
  • Consider the inclusion of a WiFi-capable Arduino board, explore transforming output from LED ignition to SMS sending (i.e., “time to clean the litterbox!”)
  • Develop a chassis that can encompass all these components, convey the utility (cat-shaped?), and inspire admiration

Please  let me know your thoughts or suggestions in the comments!



*I hope! My LED is rather dim in this lighting.


Mucking about in Arduino: Smart RGBs, Potentiometers, Motors, oh my!

This week, we dove in on some additional Arduino-compatible pieces of technology—

Here’s a look at my pared-down sequence of the NeoPixel smart RGBW LED sample code:

This is what a potentiometer can do when paired with a green LED:

And here are some of the speed and acceleration variants easily achieved with a rotating motor:

Octavio the Octopus

This is Octavio.


He is a young octopus, just trying to figure out his place in the big blue sea.


He has eight tentacles. He uses them to move around, interact with his environment, and wave hello.


When it gets dark, his bioluminescent spots make him fun to be around. Here he is with a jellyfish, a recent acquaintance and new friend.

He is also very soft. So, even though he does not think of himself as a pillow, he will sometimes let you use him as one—provided you ask politely.


Thanks Octavio! And good night, Octavio.

~ ~ ~

Now, for some BONUS *~*MaKiNg PiCs*~*

the pattern (internal lines were for measuring in Illustrator):


tracing on our stretchy velvet…


all cut out…




and stitching is underway!


not shown: some soldering, tedious insertion of LED wires and stuffing into eight separate legs and a plastic orb. But now, the finishing stitches…


et voila!




What do you call an octopus with one tentacle?



But Emilio didn’t come out of thin air! Or water. No, he came from Mood Fabric, Tinkersphere, and the Visible Futures Lab.

Once I’d acquired some blue fabric and pink LED wire-bands, I was ready to put the below pattern into action:


I cut out one of each except for the ‘triangle,’ of which I needed four. Once I sewed them almost all the way together, I had to solder together this simple arrangement:


I split the 20 LEDs evenly between the head and tentacle, and then finished the stitching by hand. Which gave me this:


I think it’s safe to say Emilio’s a pretty cool-looking guy. But the party really gets started when the lights go out.



Ciao, Emilio.

Now you’re really pushing my buttons

Arduino exercises continue in week three, introducing us more intimately to LEDs and how to manipulate them.

First, I explored sketches that enabled me to use click-buttons to turn an LED on, off, and modulate its brightness:

Then, I borrowed a multicolor LED bulb from Sowmya (and some re-wiring instructions from Jingting!) to create some psychedelic configurations: