There are sensors sensitive enough to pick up minute ... There are hundreds of different Arduino builds on the internet, but if you have the know-how, you can create gadgets no one else has ...

The sensor shown here is essentially two plates mounted side-by-side, attached to an Arduino Nano using the ... with a dielectric constant that is different enough from the air surrounding the ...

It runs on an Arduino MEGA 2560 PRO (or similar microcontroller) and supports a wide array of additional hardware including pressure transducer, water level sensor, flow meter, OLED display ...