Relatively inexpensive, transportable and deployable sensors are produced all over the world for a variety of analytes. Broadly defined, sensors respond to a physical or chemical property, providing an interpretable output. For our purposes, a main distinction of a sensor versus a sampler is that sensors do not require laboratory-based analyses, and provide outputs in near-real time. Though we often think of sensors as part of the electronics field, plenty of analog sensors have been available for decades. Common analog sensors include things like mercury thermometers and classic barometers. Common digital sensors include things like voltmeters. In Public Lab, we're interested in a broad variety of sensors, both analog and digital, designed for measuring chemical and physical properties in air or water. ###Air Sensors There are a ton of different air sensors on the market these days, with common analytes including carbon monoxide (e.g. smoke detectors), temperature, humidity, particulate matter, and more. Some of these sensors require a digital interface with a controller and data logger, others are analog. Please see more information [here](/wiki/air-sensors) and check out air sensors in the table below. Please add more sensors that you've used! [embed table] ###Water Sensors Water sensors are available for several analytes, such as salinity, pH, and depth. Like air sensors, water sensors may be digital or analog. Any digital water sensors that are meant to be deployed will require water-tight enclosures for the electronic components. Please see more information [here](/wiki/water-sensors), and check out and add more sensors to the table below. [embed table]...