Devices and methods for controlling collection of liquid sample are described. In an example, a microfluidic device can include an analytical device and an actuator. The actuator can be connected to the analytical device. The actuator can be operable to absorb fluid. The actuator can guide the absorbed fluid to an input layer of the analytical device. The actuator can deform in response to an occurrence of an absorption condition. A degree of deformation of the actuator indicates a volume of fluid collected by the analytical device.