Week 6:


     This week, our designated group members doing the electrospinning went into the Materials Engineering Department lab and mixed the chemical compounds that will be used to do electrospin polyethylene and the polyethylene and carbon black compounds.  They also learned from experienced electrospinners some of the variables needed to be set to spin polyethylene.  After the compounds have set for a while they will electrospin the fiber next week.
     In the engineering lab this week, the we figured out how to use the load cell by calling the company who created it.  We borrowed a power supply to apply 5 volts and a volt meter to read the voltage for ensuring that the load cell worked properly which it did.  We also researched how the load cell actually works.  The way it is used is through a series of resistors.  As the resistors stretch due to pulling on the load cell, the output voltage changes due to the change in resistance.  Using this output voltage, the force applied to the load cell can then be determined.  Finding this will then allow for the calculation of the stress and strain on the fibers tested.  Below is an image of the circuit board that is normally used in a load cell.  It shows how the series of resistors work to give a voltage output based on the bending of the circuit board [5].

Figure 1:  Circuit Board of a Load Cell [5]

     Now that we have figured out how the get the load cell working, the next job is to find a way to attach it to the NXT model we created.  It has to be attached in a way that it will be immobile, so the voltage reading is as accurate as possible.