A micromachined double lumen microdialysis probe connector with incorporated sensor for on-line sampling

In this paper, a micromachined double lumen microdialysis probe connector f or on-line, in-vivo sampling is presented. The connector forms an integral part of a double lumen type microdialysis probe and guides the flow of samp le fluid ('dialysate') directly into a flow cell with space for integrated sensors. Basically, the connector is a sandwich construction of two, multis tep KOH etched silicon wafers which, after bonding allows the easy insertio n of two concentric fused silica capillaries, required to construct the pro be. For the experimental evaluation of the performance, in this work, a chl oride selective sensor was integrated in the flow cell of the connector to continuously measure the chloride concentration in the dialysate flow. It w ill be shown that by adopting micromachining techniques, the induced lag ti me of the measurement can easily be decreased by a factor of more than 5, a s compared to a conventional probe connected to a flow-through sensor. Anot her benefit of the proposed direct coupling of double lumen microdialysis p robes and microfluidic structures in silicon, is the fact that all critical fluidic connections, especially the probe/sensor connection, are kept insi de, making the microanalysis system more rigid. (C) 2000 Elsevier Science S .A. All rights reserved.