A lot of research has been devoted to creating electrical devices that emulate biological sensors, including:
- Visual: Cameras, color/light intensity sensors
- Auditory: Microphones, ultrasonic sensors
- Tactile: Pressure sensors, temperature sensors
- Balance: Gyroscopes, accelerometers
However, I have yet to find a comprehensive sensor/processing algorithm to detect and interpret odors. Certainly, there are "olfactory" sensors which are dedicated to a specific purpose, such as carbon monoxide detectors, and other hazardous gas detectors. But I have yet to find a general purpose sensor/processing algorithm that can readily detect and interpret odors within the range and resolution of a human nose.
Do such sensors/algorithms exist? If so, what are they and how do they work? If not, what are the primary obstacles to developing them?