To get an air sample in the past it required a human to be on site, fill up a canister with the sample, and drive back to the lab. The can autosampler autonomously collects up to 16 samples, which could span anywhere from a day at a sample every hour to two weeks with a sample taken every day. The autosampler allows experiments to run autonomously for up to two weeks at a time. If there are any errors that occur during the sampling, an email will be sent out notifying the technician of any possible errors.
The machine is lightweight, and easy to use. It is designed to fit eight cans on top and another eight underneath. The pump is connected to a relay controlled by the computer so it can be activated on demand. The power supplies and control boxes are mounted to the base along with a two-way switcher valve. There is enough room to easily attach cans up to 2 liters, larger ones can be fitted with a small hose attachment. It can also be used in an aircraft to take samples automatically or manually. Operating in an enclosed, dynamic environment necessitates quiet operation and a minimized amount of vibration.
The first prototype Can Autosampler is comple. Currently, we are working on the custom computer control application that will execute a state-machine algorithm. The state machine diagram (Figure 12) shows the different steps that the machine follows to take samples. The central loop in the diagram represents a series of operations required for each sample collected. After the loop is completed 16 times, the instrument goes to the finish state and turns off.
The top of the instrument is composed of a web-like series of silica steel tubing converging into the 16-position stream select valve. The cans are attached to the top by the hand tightened quick-release fittings. The plumbing must be airtight because the air samples may need to be contained for up to two weeks.
The next version of the autosampler will contain its hardware internally. The 16-position stream select valve will most likely be replaced by an array of solenoids. This might also be true for the two-way valve. The solenoids are much less expensive and are easier to work with. By enclosing all the hardware internally, the second generation will have one power cord and one USB cable instead of the complex system of wires on the current version.