Dec '15
Hi, I would like to make a mat to sleep on and measure breathing using force / strain / pressure. I believe it should be possible to do this will cheap components such as https://www.robotshop.com/en/sfe-piezo-element.html arranged in an array in a mat the person would sleep on. Although the pressure changes are small, they should be quite measureable (~1% change in pressure as the lungs expand / contract). Unfortunately I have no experience in hardware so I’d like to find either an existing kit and purchase it or a detailed tutorial.
Is anyone else interested in a breathing detector like this? Thanks in advance!
Allan
1 reply
Dec '15
▶ allancto
@allan Nice project, but we’re not aware of any kit which addresses that type of application. You’d need to learn about programming, microcontroller, electronics and sensors.
Dec '15
Hi is it possible to hook up a loadcell on one channel of the loadcell shield and also an LVDT displacement transducer on the other channel of the loadcell shield?
1 reply
Dec '15
▶ mathews-2
@mathews The Load Cell Shield is intended to work with Load Cells (strain gauge devices). We didn’t test it with with displacement transducers so we can’t confirm that it’ll work.
Jan '16
Is it possible to stack two Load Cell Shields onto a single Arduino, allowing the reading of a total of 4 Load Cells? The board looks stackable in this way, but I don’t see how to change the analog input pins that would be used for the second Load Cell Shield.
1 reply
Jan '16
▶ gerald-7
@Gerald The Strain Gauge / Load Cell / Wheatstone Amplifier Shield amplifier shield uses A0 and A1 analog inputs on the Arduino.
Therefore, you unfortunately can’t stack two shields similioultanesly to read 4 Load Cells as both shields will use the same analog pin (A0 or A1).
A workaround for this is to bend the two pin headers (A0 and A1) on one of the shields and wire them to a different analog input on the Arduino (for example A2 and A3) using M/F Jumper Wires.
The same idea is used in this blog post.
Jan '16
Is there an inherent precision to this system, or is that something that can be adjusted? I’m considering this for an application that would measure the weight of pills, and distinguish between different types of pills, so it would need to have a precision in the +/-10mg range.
1 reply
Jan '16
Gday Mr Daouas My Employer has given me a project to make a very budget load cell display using four load cells under a tank. Is it possible to just parrallel all four letting them produce their own average and using that analogue input into the shield as I have seen done into other “digitisers/amplifiers”, then stacking a display(yes bending pins and re assigning as per above blog). Thankyou in advance for any consideration.
1 reply
Jan '16
▶ jeremiah
@Jeremiah The Strain Gauge Shield won’t be appropriate for this type of precise measurements. FYI, the smallest cell weight capacity we offer, which is 100g Micro Load Cell, has a +/-50mg error rating.
Jan '16
▶ paulg-7
@ Paul G You can probably use 4 load cells stacking two Strain Gauge Shields using the workaround mentioned above (bend the two pin headers (A0 and A1) on one of the shields and wire them to a different analog input on the Arduino). Then, you stack the display shield. Please note that this has not been tested. You’ll probably have to appropriately calibrate the 4 load cells in your Arduino code to obtain meaningful readings.
