Versatile method for bonding hard and soft materials

Abstract

We report a versatile method for bonding dissimilar materials which is an important issue in the fabrication of micro- and nanofluidic devices. Recently we have demonstrated a simple, surface modification based method for irreversible bonding of thermoplastics to polydimethylsiloxane (PDMS) at room temperature. Here, we present the applicability of this technique for bonding various hard materials including metals and plastics to a soft material like PDMS. An irreversible bonding was formed when the hard material activated by oxygen plasma followed by aminopropyltriethoxy silane (APTES) modification was brought into contact with the plasma treated PDMS and incubated at room temperature. The modified surfaces were characterized by water contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The analytical data confirms the presence of silane moiety on the treated surface. The tensile strength values of the bonded devices were in the range between 40 kPa similar to 700 kPa, depending on the type of materials used for bonding. The tested hard materials include gold (Au), platinum (Pt), copper (Cu), iron (Fe), aluminum (Al), polypropylene (PP), high density polyethylene (HDPE) and Teflon and the soft materials include PDMS and butyl rubber.