In assembling a portion of a microfluidic device by conducting bonding action by contacting faces of opposed bondable materials, one comprising a flexible sheet, the method, while maintaining continual contact of the faces in a region R2 until bonding is completed, of employing repeated make-and-break-contact manufacturing protocol on a region R1 of the contacted faces of the bondable materials, thereby over time neutralizing the tendency for permanent bonds to form in the region R1, thus to enable making and breaking actuated movements of the region R1 of the flexible sheet relative to the portion of the other material that it opposes.