Development of a CTD System for Environmental Measurements Using Novel PCB MEMS Fabrication Techniques

The development of environmental continuous monitoring of physicochemical parameters via portable small and inexpensive instrumentation is an active field of research as it presents distinct challenges. The development of a PCB MEMS-based inexpensive CTD system intended for the measurement of environmental parameters in natural waters, is presented in this work. Novel PCB MEMS fabrication techniques have also been developed to construct the conductivity and temperature transducers. The design and fabrication processes are based on PCB MEMS technology that combines Cu-clad liquid crystal polymer (LCP) thin-film material with a direct write photolithography tool, chemical etching and metallization of layers of electroless nickel, gold, and platinum. The basic principles of a planar four-electrode conductivity cell and the resistive temperature device are described here as well as the integration and the packaging of the microfabricated sensors for the underwater environment. Measurement results and successful field evaluation data show that the performance of the LCP thin-film microsensors can compete with that of conventional in-situ instruments