Hi,
I need to measure weights ~ 1KG for a project and am looking to see what the most compact way of doing so is. I looked at FSRs but they are not repeatable or accurate. I couldn't find a good way of using a MEMS pressure sensor for measuring weight.

The next best option is to use a load cell like this one

http://www.ebay.com/itm/like/221642694047?lpid=82&chn=ps

I have seen them in kitchen scales, and assume them to be accurate. I tried to hook one of these up to an INA125 and Arduino board, but needed to press it really hard to get a reading. Do I need to stick this load cell to a substrate to generate strain.

Thanks

 

hi,
The load cell you linked to has the attached specification.
If you use 10Vdc excitation it will output 1mV/Vex = 10mV at 1Kg full scale.
It is customary to use a Instrumentation amplifier [IA] to amplify the low level signal to a more useful voltage.
A typical IA gain would be set for 5Vout/10mV = 500, the 5Vout would then be converted using an ADC converter, if you planned to display the weight digitally.
E
Description:

• Model:Weighing Sensor
  Rated Load: 1Kg
  Rated Output: 1.0mV/V±0.15mV/V
  Zero Output: ±0.1mV/V
  Creep: 0.03%F.S./30min
  Input End: Red+ (power), Black-(power)
  Output End: Green+(signal), White-(signal)
  Recommended operating voltage: 3 ~ 12 VDC
  Maximum operating voltage: 15 VDC
  Input Impedance: 1115±10%Ω
  Output Impedance: 1000±10%Ω
  Protection class: IP65
  Total Size: approx. 3.15 x0.50 x 0.50 inch
  Cable: 0.8 x 20 cm (diameter x length)
  Material: Aluminum Alloy

Do I need to stick this load cell to a substrate to generate strain.

This load cell is designed for mounting between a Base plate and the weigh platform.