It is provided a microfluidic analytical device and platform for autonomous immunoassays such as ELISA comprising a porous layer having at least one slot therein and a porous arm extending from the porous layer and pivotable about the arm's root, the porous arm being pivotable between an off position wherein the porous arm is spaced away from the slot and an on position wherein the porous arm is disposed in the slot and the hydrophilic element spans the slot to define a fluid flow path across the slot; a heat-responsive shaped memory polymer (SMP) disposed underneath the porous layer, the SMP being elastically deformable in response to being heated to move the porous arm between the on and off positions; and a heat source in heat-conducting contact with the SMP to elastically deform the SMP.