First off, I'm pretty much a newbie here. So if you think I'm in the wrong forum, or I am not being clear enough just let me now. Thanks.
Yes, you are in the "wrong forum" with this posting - this posting has -nothing- to do with LEDs, or multiplexing - next time, put your post in a better spot (something like this would probably go in Motors, Mechanics and Power).
I am trying to control a Miga NanoMuscle (http://www.migamotors.com/Media/NM706-Super-TechNote.pdf) using my Arduino FIO. I have a opamp set up to run a pin buffer (http://www.datasheetcatalog.org/datasheets/228/53986_DS.pdf). The signal is being sent through pin 13 of the FIO to pin 3 of the opamp.
At best, a 741 can source only about 40mA of current from its output pin. This is also the maximum amount of current that an output pin on a standard Arduino can provide. With that said, your "datasheet" for the Miga NanoMuscle doesn't seem to supply any information on what its current needs are, but I am willing to bet that such an SMA actuator, since it is basically a resistor, will require much more than 40mA of current to move. I would first find out what its current needs are...
You need to go back to http://www.migamotors.com/Downloads.html and download the "Complete NanoMuscle NM70 and Rotary Actuator Package" (last App and Tech Notes link); uncompress it, and look in the directory "NanoMuscle-Technical-Data". Inside that directory you will find a document entitled "NM70-Super.pdf" - that is the "real" datasheet (I believe, based on your picture) for the device you have.
If you read page one, you will find out a couple of important things: The maximum voltage (as far as I could tell) for the HS device is 4.0V @ 470mA, while the HE version is 3.5V @ 410mA - you don't say which version you have (and I can't tell from your low-res pic). You need to figure that out, because it is important. Once you know that, you then know what you need to actuate it (you also need to read the entire datasheet, because it has a lot of other important info about the mechanical actuation needs, electrical needs, etc).
That 741 won't actuate it; you need to drive it with a transistor or mosfet, minimum - but you need to calculate everything carefully so you only supply the needed voltage, and that your part can supply the needed current (not just any old transistor or fet will do - but most small fets should be up to the task). The logic level output of your FIO should be ok (I think it is 3.3V HIGH, right?); so you'll need a transistor or fet with a "fully on" voltage level of 3.3V or less, and a current rating of at least 500mA (or greater - I would shoot for 600mA), so it can supply the current to the NanoMuscle.
Likely you haven't harmed the NanoMuscle in your experiments; but the 741 might be toast (since you were trying to draw more current than it could supply) - but the 741 can be a hardy beast, so who knows!
Hope this helps...