Open-Source Microcontrollers for Science - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 60

To make the work of programming sketches really easy, I strongly recommend utilizing
libraries whenever possible. Libraries provide extra functionality for use in sketches. For ex-
ample, they are used when working with hardware or manipulating data. The open-source
Arduino programming community has probably already-writen libraries for most of the in-
dividual mini-programs you need to write to get your own piece of open-source hardware
working. To use a library in a sketch, select it from the Sketch > Import Library menu. This
will insert one or more #include statements at the top of the sketch and compile the library
with your sketch. For a list of libraries, see htp://arduino.cc/en/Reference/Libraries . Some of
the most commonly used libraries are included with the Arduino software, but the global col-
lection of open-source libraries is continually expanding and also being developed for other
Arduino-compatible boards (e.g. Sanguino, Lira, TinyDuino, etc.). If your research demands
installing non-Arduino libraries, see this very straightforward guide. 25 As you research group
becomes more adept at using Arduinos, you may want to develop your own libraries and as
discussed in Chapter 2 , share them to benefit from the global open-source support. For step-
by-step instructions, see the Arduino hacking tutorial. 26

4.5 Example: The “Polar Bear” Open-Source

Environmental Chamber
Arduino microcontrollers can be used with a combination of relatively inexpensive supple-
ments available in any hardware store or Wal-Mart to replace very sophisticated and expens-
ive research tools. Consider the research-grade environmental chamber. An environmental
chamber is simply an enclosed volume, in which the temperature and humidity are controlled.
They are required for many experiments where it is important to control the environment
in disciplines as far removed as biology to civil engineering to materials science. Our group
was interested in the effects of temperature and humidity on the solidification and mechanical
properties (e.g. interlayer adhesion) of various polymers undergoing an extrusion process. 27
We looked online for commercial environmental chamber systems that would be appropriate
(both humidity and temperature range and the necessary volume to it a RepRap 3-D print-
er comfortably). Our requirements were modest and flexible, but the lowest cost commercial
solution was still over US$6500. This seemed unnecessary considering the functionality of the
device so we decided to make our own. The design that follows highlights some of the func-
tionality of the Arduino including the ability to both measure and produce an output based
on that measurement.
In addition, the open-source environmental chamber showcases the Arduino's ability to
solve research-related instrumentation challenges for a small fraction of the cost of commer-
cialized solutions. It is unlikely that you will want to use our environmental chamber design
for the same purpose as our lab, but if you need a similar environmental chamber—perhaps a
larger one with a greater temperature range—the underlying code and design we have deve-
loped is easily adapted. This again is the power of open source, you or anyone else will have
a much easier time designing and building an environmental chamber after finishing reading
this section and having access to our code. As many people begin to use this design, improve
it, and feed it back into the community; the next time my lab needs an environmental cham-
ber, I am quite confident we will have access to a superior designs (e.g. higher performance
for less cost).
This system was designed and built in less than a semester by Rodrigo Faria, an under-
graduate student researcher in my group with assistance with other members of the group