- Using a Puck or Shim
- ELF System and Calibration
As far as we know, sensors can handle humidity but not water saturation/submersion. They are not considered to be waterproof, even though the outer material (mylar) is. One reason is that the connector/tab area has an opening for connection of the traces.
From what we have heard from customers who use the sensors around magnetic fields, there is little or no effect. We do not know what would be the response of the ink around radiation.
Depends on the temperature the lights are exuding. Sensors can handle up to about 180 degrees in some cases, but 165 degrees is the maximum recommended. See data sheets.
Yes, to a small degree. We have designed the sensor with both traces to one side of the sensor so there is minute amount of space through which noise can travel.
Using a Puck or Shim
A puck/shim is an object that is used between sensing area (button) and load that serves as a funnel for a load that is too large (portion outside sensing area), or as an enlarger for a load that is too small (less than 70% of sensing area, or area of less than 0.077 square inches).
Must be between 70% (0.2625 inches / 6.67 mm) and 100% of sensing area diameter.
Plastic is best. Rubber is more sensitive than plastic, and steel is less.
We wouldn't use something like a cheese-grater surface because it will puncture the sensor. Smooth bumps are best. Sandpaper surface is questionable...should be fine as long as there is no shearing/sliding.
If the load you are measuring is made of a hard material, like metal, using a plastic puck would give more accurate readings. Also, if your load is too big, use a puck to capture the load that falls outside of the sensing area. If load is less than 70% in size (e.g. a pen point) than sensing area, you need to use puck so PSI is lower.
A flat surface is best. Materials can make a difference on output, see above.
Breaking it in. This conditions contacting surfaces of the ink, which will improve performance and repeatability.
Could be greater than standard ± 5% error.
The inks are resistive: the greater the constant force, the less the resistance.
2-3 seconds for constant load. If using 'spongy' load, could take 10 seconds.
Imagine tapping your fingers or typing. Time between can be short...no exact time. Calibrate in time frames you will be using when testing/measuring.
This is the weight you should apply when conditioning the sensor, 110% of the maximum load you will be measuring. That way you get higher resolution around the load with which you will measuring.
Recondition the sensor every month, if haven't used it for that long. Store your sensors in recommended, protected environment.
ELF System and Calibration
30 grams / 0.066 lbs.
The current system electronics allow for 1 sensor input at a time, but you could use multiple ELF systems hooked up to a serial port adapter. You would need to run a separate instance of the ELF software for each sensor. (requires 2.01 patch)
Calibrating allows you to: adjust the gain/sensitivity of each sensor and select unit of measure (grams, pounds, newtons, etc.) by converting raw percentage units to calibrated units. If you use the sensor without calibrating it, the data you get shows as a percentage of the maximum range of the sensor. Furthermore, there is variance between sensor runs, which could give different resistance values when applying the same load if not calibrated prior to testing.
You should calibrate as you would test: use same load weights and materials, temperature and time intervals.
No, you should calibrate to 110% of the test load so the sensor and system shorten the force range to give greater resolution. This is the same as adjusting the gain/sensitivity of the sensor.
At no load, the resistance is 5M Ohms. At full load, it is 20k Ohms.
If you need to adhere the sensor to a surface, apply the adhesive to the shaft of the sensor, not to the sensing area. We wouldn't recommend adhering the load to the sensor because any adhesive can apply a load. Also, an adhesive (e.g. glue) could make the load uneven.
The durablity of the FlexiForce sensor depends on the conditions to which it is exposed: magnitude of the load, the interface material, and the direction of the load (minimize shear). Under "normal" limits, the sensor typically can perform up to 1,000,000 cycles/applied loads. Our tests were performed by applying a 50 lb. impact load on the sensor, which was between two pieces of metal.
Temperatures that are too high or low, water-submersion, sharp objects, sandpaper or similar surface.
If you apply a load that is a bit more than the maximum force range (say, 10% more), you shouldn't damage the sensor. However, you should stay within the given force range.
The sensor is made to be flexible, but don't fold on sensing area.
We do not recommend cutting the sensor. But, you could cut along the shaft of the sensor as long as your electronics were touching the leads.
You need to build your own circuit (see A101 data sheet for example) and connect that to a device that will read output (e.g. oscilloscope, voltmeter, etc.).
FlexiForce is a trademark of Tekscan, Inc.