Electronic Diaper

Long gone are the days of peeking at a diaper to determine if it's that time or not.  You know what I'm talking about.  Introducing the Electronic Diaper:  a high-tech interior garment for infants with a sensor that monitors your child's comfort level.  It provides instant audible feedback by way of a buzzer as well as a persistent optical sensory notification system by way of an  LED.  In theory, it works by making use of a voltage divider which is extremely sensitive to wetness at the tip of the probe.  When wet, electricity flows across the leads of the probe but with some resistance.  The voltage drop is measured through the microcontroller's analog to digital converter every second.  As soon as any voltage is detected, a buzzer goes off like a siren followed by chirps at 5 second intervals for as long as wetness is detected.  The LED turns on and stays light indefinitely, however, at the onset of wetness.  So after a diaper change, a reset is required.

 

Step 1: Bill of Materials

Hardware
PC with serial port
PIC burner and dev board w/ POT, DB9 serial (for debugging and development) 
Serial cable (for debugging)

PCB making stuff
Single sided Copper clad board (3" x 3")
Paint thinner
Hydrogen Peroxide
Muratic Acid
Plastic tray
Laser printer
Laminator
magazine w/ thin and glossy pages

Components
PIC Microcontroller 16F88
18 pin socket
LED
buzzer
220 Ohm resistor
1 MOhm resistor
4.7 KOhm resistor
0.1 uF catalytic capacitor
on/off switch
2 lead ribbon cable


Software
Digital Diaper software by carlitos (hex and source code)
Eagle Software (if you wish to modify PCB)
JAL compiler (if you wish to modify code)
Tera Term Pro (for debugging)

Miscellaneous
Paper
tape
Permanent marker
Hot glue and gun
Cloth
Scissors

Comments

[mowdish]

This is a brilliant idea. That said, the buzzer worries me a little. It didn't sound to bad in the video, but if your baby doesn't like the sound, then this is classic negative reinforcement. If your baby loves the sound, then it is positive reinforcement. Probably not healthy either way. If you put in a delay of 1 or 2 minutes, then your baby won't associate the peeing with the noise.

[Dr Qui]

Bit of a double edged sword maybe.

Now there an Oprah I cant wait for "my dads crazy invention makes me pee myself every time I hear a fire truck, ambulance, police siren etc"  LOL

A negative sound would be of use in the nappy around potty training time.

You could put one in a potty that has a positive sound.

The flashing LED is a good idea.

Keep up the good work.

[carlitos]

That would be great. Then I come out on Oprah riding my antique bicycle!
Looked it up, and this stuff is actually patented and a wireless version for seniors is already out. Hm

[Dr Qui]

I'm almost certain the potty with this in it is patented too.

Here's a theme tune for when you ride you bike around Oprah's couch. :-)
http://www.youtube.com/watch?v=uoC7kuFV3oY

[carlitos]

That's so true. What was I thinking!
A high-end solution is to have a wireless WI-FI transmitter and effectively send a text to a cell-phone instead of a buzzer like caitlinsdad suggested.
I could do this with a wifly RN-121, but it will get really bulky if it isn't already. 
Maybe one day Huggies will come out with these.  Each diaper could 
have embedded conductive thread where you clip on a SMT board inside a pocket.  Like if diapers were not expensive enough already!

    if (firstiswet) then
+       delay_1s(120) -- wait 2 minutes 
       dobuzzchime 
   

[mowdish]

I wonder if you could do it with an RFID tag. Break the circuit on the tag so that it is only functioning when moisture is detected. Then the RFID reader and wireless (or wired) transmitter could be in the crib/stroller/etc.

BTW, is there enough water in poop for your probe to detect?

[carlitos]

I have not worked with RFID and reading about them sounds like a good idea with an active tag.

Good question. I'm guessing yes, there is enough most of the time.

I think one of these days I'll "install" it during a nap and hope she does not mind when she wakes up. Maybe I can catch that rare moment in the name of science and report back.

[hubi]

Hi,
this is a cool idea!!!
but you could do all of this with only one 555, easier with two

[caitlinsdad]

Ha, it should really tweet a message to the nanny to attend to the diaper change...

[neuropol]

Every time a child goes to the bathroom a buzzer goes off and lights start flashing. I can see a pavlovian response later in life. I like it.

Maybe this could be adapted for coworkers?

[Foxtrot70]

Interesting, there are possibilities of miniaturization, more importantly have you tried to get a patent?

[jeff-o]

Ha, that's fantastic. I think my son and daughter would try to yank it right off though! Be sure to let us know if your test subject ever gives it a try.

[depotdevoid]

Oh, that's hilarious! Thanks for sharing!