Weight Sensing Tote Bag

This instructable is for a weight sensing bag. It helps people who carry a lot in their bags and improves on scales by providing constant ambient feedback and an automatic warning alert for excess weight. 

How it works

It works by using a force sensitive resistor to measure how much the strap is pressing on the wearer's shoulder, and using the value to control how fast LEDs pulsate, or how many LEDs have lit up (when a switch is pressed), giving the user feedback. When the wearer wears excessive weight (currently calibrated at approximately 10-11 pounds), the LEDs blink rapidly to warn the wearer. The entire apparatus is powered by an AAA battery and controlled by a Lilypad Arduino, which is attached to components by conductive thread sewn into the surface of the bag. 

Illustrations and photographs of the bag are below. 

Step 1 Components

Here is a list of equipment you will need for this experiment:

Lilypad Arduino - A sewable version of the arduino microprocessor

Breakout board and USB cord - connects lilypad to computer

Lilypad battery pack

4 lilypad LEDs

Lilypad switch

Force sensitive resistor

Conductive thread - 4 ply tends to fray, but has much lower resistance than 2 ply

Needle and threader - threader is vital for 4 ply thread

Alligator clips - vital for testing circuits. Sewing is too slow to test with. 

Fabric glue and fabric paint - to seal threads

Tote bag - any thin fabric one will do 

Comments

[rimar2000]

I did not read it yet (the electronics is not my forte), but the idea is very interesting.