Using smartphones in experimental physics teaching offers many advantages in terms of engagement, pedagogy and flexibility. But it presents drawbacks such as possibly endangering the device and also facing the heterogeneity of available sensors on different smartphones. We present a low-cost alternative that preserves the advantages of smartphones: using a microcontroller equipped with a large variety of sensors that transmits data to a smartphone using a Bluetooth low-energy protocol. This device can be lent to students with little risk and used to perform a wide range of experiments. It opens the way to new types of physics teachings.