In this study the plasma polymerised acrylic acid (ppAc) biocompatible films has been shown potential usefulness to bond any types of two substrate materials without applying a load at room temperature (???25 oC). To understand the bonding mechanism of plasma ppAc film at room temperature the interfacial adhesion is an important factor in determining the performance and reliability of MEMS/NEMS systems. In this paper the effect of covalent bonding between two chemically activated surfaces has been discussed. It is also know that at small roughness values at interface the adhesion is mainly due to van der Waals forces acting across extensive non-contacting areas. Therefore, the contribution of both covalent bonding and van der Waals forces at contact and non-contact areas at the interface respectively has been also discussed in this paper. Advantages of this bonding technique in fabrication of recycled and reusable MEMS/NEMS, bio-MEMS/NEMS, organic micro/nano fluidic devices, lab-on-a-chip etc. has been also discussed.