For the course “Measuring for water” (part of the minor “De Delta Denker“) thirty 3rd year Bachelor students had to develop their own sensor to measure something related to water. They used Arduino to control and process the data from the sensors. After one day getting acquainted with Arduino the students started to think about their own sensor. After three days of developing, constructing, and testing they came up with a wide variety of instruments. Tipping buckets, psychrometers to measure humidity, turbidity sensors, salt concentration meters, discharge meters, water level meters, were all developed in a short period of time. Below a short photo impression of the sensors.
See also the blog post of Rolf Hut: “Gecontroleerd klooien is een goede les” (in Dutch)