Fabrication of polymer-based micro devices: Formulation and study of the paste

We investigate in the present work the fabrication of polymer-based micro-fluidic and micro-mechanical devices using sacrificial, resistive/conductive pastes, through a screen-printing process. An organic sacrificial paste is first screen-printed onto a substrate, building the future empty space (channels, cavities…) where it lies. Then, a resistive paste based on thermosetting polymer resin and graphite is deposited onto the previous layer. Finally, the sacrificial paste is removed at 150 °C by sublimation through the composite, thus yielding the desired pattern. For such applications, the key is naturally the formulation of the pastes. In a previous work, we already proposed a potential formulation for the organic sacrificial paste, based on polyols [1]. In the present paper, we will focus on the formulation of the cover paste, which must be adapted rheologically for the screen-printing process, but also chemically due to strong potential interactions between the sacrificial layer and the over-layer. Finally, micro-devices such as simple fluidic channels and suspended structures were produced and shown to be operational, demonstrating the high potential of our process.