Flexiforce Sensor Calibration

Hi,

I’m a complete and utter novice when it comes to these kind of things. I’m trying to use a Flexiforce (100lbs) pressure sensor to monitor pressure in mmHg for a fabric tourniquet.

I’m falling down at the most basic step: http://www.tekscan.com/pdf/FLX-Flexiforce-Calibration-QuickStart.pdf
I’ve plotted my pressure in mmHg against resistance, and have a decently linear conductance output. Now that’s all well and good but what do I do with that information to change my code to calibrate it?

Here is my code:

// Flexiforce quick start example
// Reads A0 every 100ms and sends voltage value over serial

void setup() 
{
  // Start serial at 9600 baud
  Serial.begin(9600); 
}

    void loop() 
{
  Serial.print("Time: ");
  float time = millis()/1000;
  Serial.println(time);
  // Read the input on analog pin 0:
  int sensorValue = analogRead(A1);
  float width = 0.18; 
  float length = 0.0254* 9;    //Tourniquet measurement in meters 
  float area = width*length; 
  
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
  //float voltage = sensorValue * (5.0 / 1023.0);
  //Max mmHg (length 25') = 152, 110lbs
  
  float forceLbs = (sensorValue) *(5/1023.0)*20;
  //To calibrate: (sensorValue)*(5/1023)*y/x if linear
  float forceNewton = forceLbs*4.448221628254617;
  float pressurePascal = forceNewton/area;
  float pressuremmHg = pressurePascal*0.00750061683;
  
  
  // Print out the value you read:
  Serial.print("Force: ");
  Serial.println(forceNewton);
  Serial.print("Sensor value: ");
  Serial.println(sensorValue);
  //Serial.println(pressurePascal);
  //Serial.println(pressuremmHg);
  Serial.print("pressuremmHg: ");
  Serial.println(pressuremmHg);
  delay (3000);
}

And attached is a screenshot of my results and graph:

Please answer me as though I was a complete idiot. I would really appreciate it! Thank you

Screen Shot 2014-03-04 at 13.28.32.png