The present invention concerns a microfluidic device for mechanically induced trapping of molecular interactions comprising at least a first unit cell and a second unit cell, each unit cell comprising - a membrane chamber comprising a membrane, - a flow channel crossing the membrane chamber and having an inlet and an outlet, and the flow channel crossing the first unit cell being different from the flow channel crossing the second unit cell. Another object of the invention is a method for isolation of specifically bound nucleic acids to target molecules on said microfluidic device followed by its recovery and identification.