We tried outputting the voltage using the arduino to matlab to no avail, so we upgraded to Labview. We had to install the drivers for arduino and the arduino package for labview. We learned how to create a pictoral code to measure the input voltage from arduino, create an array of numbers, graph the data in an xy plot of voltage over time, transpose the data into excel, change the time intervals and baut rate, and use a boolean clear data function.
The voltage over time was collected in numerous trials. Trials included 2 different days, different testers, with salt, without salt, with water, without water and with salt and water. This was to emulate the change of resistance on the skin due to sweat. Sweat contains a high concentration of NaCl, which conducts electricity. We found that the addition of water and salt creates a higher measured voltage. The normal voltages range from 0 to .35 Volts. With the addition of salt and water, the voltage reaches over 2 Volts. The resistance was measured across the Orings as .99 MOHMs, so that we can calculate the conductivity.
With the testing and building of the circuit, as well as coding and output now completed, our group is to focus on analyzing the data, and creating trends and graphs.
The accompanying Labview code to interpret data from Arduino
Wheatstone bridge. Modifications included adding a resistor after the third opamp to offset the voltage to zero, a voltage diver for the op amps supplying 7.5 and -7.5 volts, and 5 V directly given to the bridge.
Note: The two other designs of a less complicated wheatstone bridge, and the circuit seen in week 6 were ultimately failed designs.
Note: The two other designs of a less complicated wheatstone bridge, and the circuit seen in week 6 were ultimately failed designs.
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