We present a novel and highly reproducible process to fabricate transferable porous PDMS membranes for PDMS-based Organs-on-Chips (OOCs) using microelectromechanical systems (MEMS) fabrication technologies. Porous PDMS membranes with pore sizes down to 2.0 μm in diameter and a wide porosity range (2–65%) can be fabricated. To overcome issues normally faced when using replica moulding and extend the applicability to most OOCs and improve their scalability and reproducibility, the process includes a sacrificial layer to easily transfer the membranes from a silicon carrier to any PDMS-based OOC. The highly reliable fabrication and transfer method does not need of manual handling to define the pore features (size, distribution), allowing very thin (<10 μm) functional membranes to be transferred at chip level with a high success rate (85%). The viability of cell culturing on the porous membranes was assessed by culturing two different cell types on transferred membranes in two different OOCs. Human umbilical endothelial cells (HUVEC) and MDA-MB-231 (MDA) cells were successfully cultured confirming the viability of cell culturing and the biocompatibility of the membranes. The results demonstrate the potential of controlling the porous membrane features to study cell mechanisms such as transmigrations, monolayer formation, and barrier function. The high control over the membrane characteristics might consequently allow to intentionally trigger or prevent certain cellular responses or mechanisms when studying human physiology and pathology using OOCs.

We present a novel method to easily and reliably transfer highly porous, large area, thin microfabricated Polydimethylsiloxane (PDMS) porous membranes on Lab-on-Chip (LOC) and Organ-on-Chip (OOC) devices. The use of silicon as carrier substrate and a water-soluble sacrificial layer allows a simple and reproducible transfer of the membranes to any PDMS-based OOC and LOC device. The use of IC and MEMS compatible techniques reduces significantly the fabrication time and the need of manual handling. Our method is suitable for automatic assembling systems, such as pick-and-place, crucial to significantly increase the throughput of OOC and LOC devices assembling. Membranes with 8 μm pore size and as thin as 4 μm are successfully transferred. The viability and biocompatibility of the transfer was assessed by culturing two different cell lines on an OOC with transferred porous PDMS membranes.

The half-cell potential of the Activated carbon (AC), due to its high double layer capacitance (EDL), remains stable in high ionic electrolyte. The open circuit potential (OCV) of the AC, with EDL of 40 – 50 F, shows a stable potential (10 mV variation) over two weeks in the cement pore solution (sat. Ca(OH)2). The OCV is less sensitive to the pH change from pH 8 to 12 (range inside concrete). The potentiometric response of a Ag/AgCl vs. AC pseudo-reference shows a near-Nernstian response (-51 mV/decade). The AC electrode can be proposed as a pseudo-reference for the potentiometric monitoring inside concrete.

This paper describes the design, modelling and experimental characterization of an electrochemical sensor array for on-line monitoring of fermentor conditions in a miniaturized cell assay. The sensor array is capable of monitoring viable yeast concentration, dissolved oxygen concentration, pH and temperature.

There is a growing interest in developing minute laboratories on a 'chip' (Lab-on-a-Chip) and micro-(bio)chemical reactors as clearly shown by the research efforts of many industrial companies and research institutes in recent years. The development of a new technological platform for fed batch fermentations in very small volume (10-300 μl) reactors in an array format will be described, which in the end will allow to improve production properties of micro organisms by rapid screening under industrially relevant conditions. One of the objectives (besides developing sensing technology) is to design and test methods to analyze and control mixing. This presentation addresses several mixing methods that can be used in micro-bioreactors. The micro-bioreactor is operated under extreme conditions like high biomass and product concentrations, high oxygen requirement and long residence time (3-4 days). With the help of Computational Fluid Dynamics simulations, the influence of the mixing method on the fermentation efficiency in the microreactor is described. These results will be supported by real-life experimental mixing data.