Capella platform

Heart of the Capella platform is a microfluidic microchip, to be hold in a specially developed chip cartridge*, and to be connected via a cartridge docking station* to a high-voltage power supply unit and, optionally, a conductivity detection unit, all of which have been developed in-house. The Capella system is supplied with LabVIEW™ based software. The different main components are described in more detail below.

CE chips

Currently, several types of standard glass chips are available. One example is the D4 design (see picture left). This is a standard cross-design for microchip CE with on-chip integrated electrodes for electrical conductivity (EC) detection (contact mode). Standard chip size is 64x5.5x1.0 mm³; standard channel width and depth are 50 µm and 12 µm, respectively; separation length is about 5.2 cm.

Chip cartridge and cartridge
docking station

Emphasis is put on the exchangeability of microchips, which are mountable in a specially developed chip cartridge* (MCC-1). Usage of the chip cartridge provides a safe and easy way for handling and operation of microfluidic glass chips in high voltage applications. Different cartridge versions are available (see picture left):

• a 4-well version, which is an open system and requires sample loading by means of a pipette/syringe

• an 8-well version, which is a closed, flushable system and is suitable for on-line applications (see below)

The cartridge is placed in a Capella CDS-1 docking station* (see picture left) by a simple click movement.

The docking station contains the electrical connections and is the user-friendly interface between the chip cartridge and the control and measurement equipment.

High-voltage power supply unit

The power supply unit PSU-4 has four programmable high-voltage output channels to control the potential of the separate chip compartments. The voltage of the PSU-4 is controlled by means of a regular PC or notebook equipped with a USB-port. The PSU-4 is supplied with LabVIEW™ based software.

Conductivity detection unit

The specially developed electrical conductivity detection unit (ECU-1; see picture) is designed for measuring signals coming from the on-chip integrated (i.e., embedded) conductivity electrodes (contact mode). The combination with the on-chip conductivity detection makes the Capella platform especially useful for determining in one run the many different metal ions and other small ions that may be present in, for example, ground water and drinking water.

Current developments

Currently, emphasis is put on redesign of the Capella platform in order to broaden the functional specifications. Other important developments that we are purseuing are the implementation of on-line sampling and CE measurement extensions, and development of alternative detection technologies such as, for example, non-contact EC detection and refractive index sensing.

*patent pending