Tyler Lorig and David Elmes - Washington and Lee University
Pam Dalton and Michele Gould - Monell Chemical Senses Center
David Zald - Vanderbilt University and
Jose Pardo - VA Medical Center, Minneapolis
all hope that, should you construct such a device, you will use it safely and successfully. We make this information available in the hope that it will provide you with better control of your stimulus and allow you to reduce exposure durations to your subjects. This information is completely within the public domain and we encourage entrepreneurs to construct and resell similar devices. Obviously, we can make no warranties about devices constructed by others.
The design described here is a modification of a design by Lorig,T.S., Elmes, D.G., Zald, D.H. & Pardo, J.V. (1999). A computer-controlled olfactometer for fMRI and electrophysiological studies of olfaction. Behavior Research Methods, Instruments & Computers, 31,370-375.
Below you will find a list of concerns that you should address as you construct any odor delivery device:
1. Flow rate - If you provide an unheated and unhumidified air stream into the nose, it is quite possible to cause your subject discomfort and possible injury through nasal drying. The olfactometer described here does not heat or humidify air so it is especially important to limit the amount of air reaching the subject. This is best done in two ways: 1) Reduce the flow rate (1.5L/min is usually acceptable) AND 2) limit exposure to blocks of approximately 5 min with 1-2 min rest periods between blocks.
2. Contamination - Contamination can arise from the air supply and contact with the subject. Contamination in the air flow may be through particulates or pathogens. Particulate contamination can come from the room air or dust in drying tubes or charcoal filters. Take care to use and regularly replace the filters in your system. Pathogens can come from the air stream if it is raised to body temperature and humidified and/or if there is some media for bacteriological growth. It is a good idea to occasionally test the air stream by exposing agar Petri dishes to the air stream and evaluate culture growth. The largest potential source of contamination arises between subject testing. The nosepeice or mask should always be replaced between subjects or thoroughly disinfected.