Sebastian Böhm

Chip-to-world interfaces for high-throughput lab-on-a-chip devices

Chip-to-world interfaces are of prime importance for the implementation of lab-on-a-chip devices in high-throughput environments. In this contribution, a matrix of interfacing methods for bi-directional small liquid exchange between chip based microchannels and robotics is presented. The central underlying principle is the use of a hydrophobic coated micromachined port in the channel wall giving direct access to the liquid inside.

Chapter 15 Microdialysis based lab-on-a-chip, applying a generic MEMS technology

Publisher Summary This chapter presents the integration of a microdialysis probe with a silicon chip, which contains the sensors, as well as calibration facilities to calibrate the sensors and a pump for the liquid handling. Because the chip contains all relevant system components for the chemical analysis, it is in fact a lab-on-a-chip. Glucose as well as potassium concentrations have been measured successfully with the system. The microdialysis concept involves the use of a hollow fibre, made partly of a semi-permeable membrane material. Originally microdialysis was introduced for monitoring neurotransmitter release in the brain, but has now become a frequently used research tool for the investigation of chemical compositions in many other tissues or body compartments. If the plastic connector of a microdialysis probe can be replaced by a silicon connector in which the sensors are placed, the better of the two systems are combined. In the case of developing the microdialysis lab-on-a-chip, the chosen generic technology consists of etching the channels and cavities into a silicon substrate, depositing metal electrodes onto a glass wafer, and bonding the silicon substrate to the glass cover.

High Pressure Gas-Liquid Mixtures Generated in a Micro-Electrolysis Cell

In this work a micro-electrolysis cell is presented that allows the rapid generation of high pressure gas-liquid mixtures. The stainless steel electrolysis cell (150 µl volume) is constructed as an integral part of an automotive pressure sensor, allowing the on-line monitoring of the generated pressure. By the application of an electric current between two platinum electrodes inserted in the electrolyte filled cell, hydrogen and oxygen gas was generated with pressures up to 1350 bar. First experiments were performed to investigate the catalytic back-reaction of the generated hydrogen/oxygen mixture at the surface of the platinum electrodes. By the application of a compensation current to keep the internal pressure at a constant value, the rate of the back reaction could be established. It follows that the catalytic back-reaction rate increases exponentially above a pressure of 800 bar. As the proposed method of in-situ high pressure gas generation is intrinsically fast and safe due to the small cell volume, a large number of these cells/reactors can form a platform for (chemical) high throughput experimentation (HTE).