Instructables member markaleung made one of those sensible wearable electronic concepts I love for their simplicity and sensibility in regard to the functionality offered: the Weight sensing Tote Bag.
Knowing the weight of a bag, especially when flying somewhere can be a question of how much money we have to shell out when in front of the check-in counter.
This DIY weight sensing bag might not be extremely accurate nor will it be the most critical part of a plane trip but knowing the weight that presses on your shoulder all day long should concern you to avoid health problems in the years ahead.
To get a ‘feeling’ of your bags weight a force sensitive resistor in the shoulder strap measures how hard the strap is pressing on the shoulder. The pressure value is then used to control how fast LEDs pulsate or how many LEDs will be lit up to indicate preset weight values.
No worry you don’t have to go around with blinking light from your bag, the system is designed to light up only when a button is pressed to give off a light code telling the approximate weight. Very smart and sensible design.
The heavy, sensible lifting in form of converting the pressure sensor data into light effects is done by a LilyPad which is powered by one AAA battery.The provided Arduino code is calibrated at approximately 10-11 pounds but can be modified to your specific needs.
Click over to the very detailed DIY instructions including the LilyPad Arduino source code to give you a quick start.