Methods for ultrasonic fabrication and sealing of microfluidics

Method of manufacturing a microfluidic device comprising an inflexible polymeric substrate, two or more flexible polymeric substrates and microfluidic channels enclosed between the substrates, the method comprising:

• a) providing a master form including rim protrusions which define an enveloping shape for the microfluidic channels to be produced and enclosed between the substrates,
• b) placing two or more flexible polymeric substrates each having a layer thickness of less than 800 μm onto the master form, wherein one flexible polymeric substrate is in contact with the rim protrusions of the master form,
• c) placing an inflexible polymeric substrate with a layer thickness of equal to or more than 800 μm onto the two or more flexible polymeric substrates, and
• d) ultrasonically welding the two or more flexible polymeric substrates and the inflexible polymeric substrate at the positions of the rim protrusions,
• wherein the inflexible polymeric substrate includes one or more preformed microfluidic channel(s) which are sealed by ultrasonically welding the flexible polymeric substrates with the inflexible polymeric substrate in step d) and wherein by using two or more flexible polymeric substrates in step d) which deform into the cavity of the master form defined by the boundaries of the rim protrusions at the same time bonding of the substrates at the rim protrusions takes place multilayered microfluidic channels are created.