A lateral flow assay device comprising a conjugate pad for receiving a quantity of fluid, and a membrane comprising a test line for determining whether the fluid comprises a target analyte. The device includes an actuator connected to a moving element comprising a shaft or a wheel. A first magnet is connected to the backing of the membrane. Second and third magnets are connected to the moving element. The actuator moves the moving element between first and second positions. In the first position, the opposite poles of the first and second magnets attract each other and maintain a gap between the membrane and the conjugate pad separate. In the second position, the similar poles of the first and third magnets repel each other and close the gap between membrane and the conjugate pad, allowing the fluid to flow from the conjugate pad into the membrane and the test line.