Bonding quality test. Inertial devices are operated at high flow rates; hence, the bonding technique must provide enough strength to prevent leakage from the interface. To evaluate the bonding quality of our proposed technique, a simple 3D-printed straight channel featuring 50 µm height, 200 µm width, and 4 cm length was bonded to a 2-mm-thick PMMA layer. A high-pressure syringe pump (Chemyx Fusion 4000 Syringe Pump, Chemyx, TX, USA) was used to inject fluids inside the channel from a small syringe (6ml). Increasing the flow rate leads to the generation of Safman-Taylor fngers around the inlet, in which the most pressure in the channel present (Section S2). Safman-Taylor fngers are generated by the movement of a viscous fluid within a porous material75,76. As the bonded adhesive tape forms a porous zone between the connecting parts, this theory is applicable for the bonding evaluation. An increase in the applied pressure leads to developments of the Safman-Taylor fngers until the bonding fails. A CCD camera (DP80, Olympus, Tokyo, Japan) mounted on an inverted microscope (IX73, Olympus, Tokyo, Japan) was used for monitoring the bonding integrity. All recorded data were obtained immediately after the bonding of the 3D-printed channels to a PMMA sheet.