Eurosensors edition:28 location:Brescia date:7 – 10 September 2014.
A bio- and haemocompatible packaging strategy is proposed for an implantable pressure sensor for continuous direct blood
pressure monitoring. A commercial sub-millimeter piezoresistive sensor was attached to an alumina substrate and a double
coating of PDMS and parylene-C was applied. The packaged device has dimensions of 2.6x3.6x1.8 mm. A surface modification
technique using O2 and SF6 plasma has been employed to tune the haemocompatibility of the packaged sensor. By enhancing the
intrinsic hydrophobicity of parylene it is possible to increase plasma proteins adsorption and minimize platelets adhesion on the
surface. Contact angle measurements were performed on parylene-coated PDMS samples after plasma treatment, using water and
whole pig blood. A maximum contact angle of 134° has been achieved. The influence of different plasma exposure times on the
surface wettability has been investigated. To study the stability of the plasma treated surfaces, the contact angle was measured
immediately and at regular intervals.