Abstract: Device and associated methods for detecting a property of a fluid. The device includes a body region and a first flexible element having a first end and a second end. The first end is fixedly located on the body region. The flexible element includes at least a first layer having a first coefficient of thermal expansion and a second layer having a second, different coefficient of thermal expansion. An electrical heater element can be arranged to heat the flexible element to induce bending of said flexible element. The resistance of a first portion of the electrical heater element adjacent the first end can be greater than the resistance of a second portion of the electrical heater element further from the first end. The device can include a heater controller arranged to supply an electrical pulse having a duration less than 5 ms to the electrical heater. The device can include a second, reference flexible element having a first end and a second end, with the first end fixedly located on the body region.