Friday, November 19, 2010

Nerd Science - Measuring

The days where a grizzled scientist would disappear into a basement lab - struggling to calibrate a breadboard apparatus for months on end - finally emerging victorious with a carefully measured value that earns him the esteem of his colleagues - yes, those days still exist. BUT, they don't have to be the way for everyone. Very detailed and accurate measurement tools exist for everyone...for a price. 

Here is a list of equipment I have used for projects large and small, some published! 

DAQs - electrical voltage and current measurements are among the most simple and easy measurements to make...heck, a trip to the hardware store will get you millivolt scale values. But, if you want a portable instrument with 16 bit accuracy or automatic aquisition, that's a different story. 

Sometimes you just want to build a weather station to install two hundred feet deep in a mine drift that intercepted a natural cavern in an attempt to estimate the cave volume by measuring airflow. If that's the case, this instrument is a great device. Very high accuracy, good support, and easy to use. I paid for my data logger out of pocket, installed it in the cave in California, and returned to find it stolen by vandals three days later. Just because he sells it as a wind datalogger does not mean it should only be used as a weather station - any voltage measurement is supported. 
Wind Data Logger- http://www.aprsworld.com/wind2/

If you want a dirt simple platform, easy enough for high schoolers to program, and a large variety of instruments, some of which are actually useful, TI Vernier Instruments is the way to go. This line of DAQs was originally developed to interface with TI calculators, but have since expanded to include 12 bit handheld portable devices. The magnetometer is top of the line for the value and performance. 
TI Vernier - http://www.vernier.com/

National Instruments is the lab-standard and the labview software is the programmable interface that runs the show. Expect to pay for as much performance as an off-the shelf platform can provide. I have heard that students who learn labview can pretty much name their price if willing to work as a labview programmer. I suspect those rumors are largely exaggerated. 
Labview - http://www.ni.com/labview/

Portable XRF - My favorite device in existance is the handheld X-ray Fluorescence Spectrometer. First of all, the instruments look like big phasers - which gives them instant nerd cred. These devices use a radioactive source, a small pellet of some isotope or a miniaturized x-ray tube, which illuminates a sample. The x-rays scatter off the surface and a silicon sensor measures the spectra of that light. There is some magic in a small computer and you get a list of elements that the spectrometer can see. Yes, there are some problems, but you do have access to the original data and it is really not suitable for measurements on material that is completely unknown. These things are best for measuring arsenic, lead and a few other heavy metals with a well characterized matrix and good standards - accurate to a few PPM at RCRA concentrations. These things would be great if they didn't cost as much as a car, and not just any old Chevy, I'm talking new BMW sedan prices here. Also you need a special certification and probably a registration with Homeland security since you are carrying around a radioactive ray gun of doom (at least that is what it looks like when the state patrolman finds it in the trunk of your car).

This is the name brand device, I attended a training session that says I am qualified to operate their devices - even have a piece of paper that says so. This is the Cadillac of handheld XRFs, but they were too durned expensive. 
Thermo Niton - http://www.niton.com/ 

So, we ended up renting one of these devices instead. This brand is a Toyota, but it would still be loaded Highlander prices if you wanted to buy one. The one I used did not have the fancy yellow racing stripes. 
Innov-X - http://www.innovx.com/

What analytical or semi-analytical equipment have you used?

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