The microfluidic immunosensor device is fabricated by the injection molding method. The master stamp was fabricated using a micromilling process. The size and thickness of the stamp were 95 × 95 mm and 1.2 mm, respectively. We used a plastic microinjection mold machine (A270C 400-100, ARBURG, Lossburg, Germany) to produce the microfluidic device in order to achieve cost-effectiveness and facilitate mass production. Once the chip was fabricated, chromium (50 Å) and gold (100 Å) were coated on the detection area for further immobilization of GBP-H1a. In this work, the ultrasonic bonding method with an ultrasonic bonder (2000X, Branson, Danbury, CT, USA) was employed to bond the COC chips. For this purpose a melting line with a height of 20 μm was made around microchannels. Once the ultrasonic energy was applied to the COC plates, the sonic energy was intensively localized on the top of the melting line. After the lines were immediately melted and then cooled, both COC plates were tightly bonded with each other to fabricate the plastic-based microfluidic device.