Dosing systems

Electronic syringe module ESr

The electronic syringe modules ESr work with glass or disposable syringes and can dose drops with a minimal volume of 1 μl. Due to the electronic piston drive, the ESr can automatically dose precise liquid volumes. The achievable dosing rates depend on the utilised syringe. Rates from 0.01 μl/s to 55.30 μl/s can be realised.

Electronic syringe module for oscillation ESr-M

By analysing the shape of oscillating pendant drops, additional parameters like the surface or interfacial compression modulus, surface or interfacial dilatation elasticity and the surface or interfacial dilatation viscosity can be determined.

The electronic syringe module ESr-M is designed for creating sinusoidal oscillating and relaxing pendant drops. The ESr-M fits on a manual or electronic dosing positioning system. The ESr-M features the following technical specifications:

• frequency range of drop oscillation: 0…20 Hz (viscosity dependent)
• harmonic volume (area) mode: typically 5…20 μl constant part, dV = 0…20 μl (for viscosities < 50 mPas)

FDDS FlexDrop dosing system

The FDDS FlexDrop dosing system with its innovative dosing technology and precise control doses small drops as small as 25 picolitres, with pinpoint accuracy and reproducibility.

An essential requirement for an accurate contact angle measurement is that the drops only wet the test surface. The microlitre-sized drops dosed with a standard dosing system have base diameters in the millimetre range, depending on the contact angle. When analysing micro-structured samples like printed circuit boards, small medical products, precision mechanics, assembly components, wires and single fibres, the challenge is to dose especially small drops.

• Flexible configuration: Dosing heads for drop volumes in the nanolitre or picolitre range are available for the FlexDrop dosing system. The system can also be equipped with two dosing heads at the same time. This allows simultaneous measurements of two droplets on structures as small as one square millimetre.
• Measurement on delicate surface structures: The smallest surface structures can be precisely analysed with droplets as small as 25 picolitres.
• Measurement with viscous suspensions or inks: Using individual test liquid cartridges makes it possible to perform measurements even with viscous suspensions or inks.
• No cleaning of the cartridge: The cartridge for test liquids can be exchanged in a few simple steps. This makes it easy to avoid cross-contamination.
• Easy cleaning of the sample surface: Due to the small droplet size, they evaporate quickly. This is particularly advantageous for quality control measurements, as the components can then be further used.
• Surface energy determination with one click: With two dosing heads, the surface energy of solids can be determined at the touch of a button.

FDDS brochurefile_download

Pressure-based double dosing system DDS-P

With the pressure-based double dosing system DDS-P, two liquid drops can be dosed onto a solid sample simultaneously. This allows the surface energy of a solid to be determined quickly and easily.

The DDS-P is primarily designed for the test liquids water and diiodomethane, but other liquids can be used as well. The liquid reservoirs hold enough liquid for up to 3000 individual measurements.

The OCA software uses the DDS-P to dose two drops, automatically measures their contact angles and determines the surface energy—all with just one click.

• fast analysis of the surface energy of solids
• objective and user-independent results
• quality assurance of coatings, surface treatments and other production processes
• surface characterisation in research and development departments with high sample throughput rates
• evaluation of surface cleaning processes

DDS-P brochurefile_download

Dosing positioning systems

The aforementioned dosing systems are mounted to the OCA contact angle meter using a dosing positioning system. Different dosing positioning systems allow either for a manual positioning of one or two dosing systems or an automatic electronic positioning of up to four dosing systems.

Manual dosing positioning systems

The single direct dosing system SD-DM can be used to manually position one dosing system. It is the ideal entry level solution for investigating surfaces and interfaces with the pendant drop method. The SD-DM consists of one dosing module carrier with fine adjustment screws for the axial and horizontal needle positioning and a connection cable.

The double direct dosing system DD-DM consists of two dosing module carriers with fine adjustment screws for the axial and horizontal needle positioning and two connection cables.

Electronic multiple direct dosing systems DDE/x

The electronic multiple direct dosing system DDE/x facilitates electronic selection and precise positioning of up to four dosing systems. The DDE/x can be controlled with the TP 50 control panel and via the OCA software. Due to the ability to electronically select and position different liquids above a sample, the determination of the surface energy of solids can be easily automated.

The DDE/x features the following technical data:

• vertical travel distance of a syringe module: 20 mm; resolution ±0.04 μm
• horizontal travel distance of a syringe module: ±4.9 mm; resolution ±0.2 μm

Dosing syringes and needles

The accessories for the contact angle meters of the OCA series include a wide range of dosing syringes and suitable needles. Inside the electronic syringe module ESr, gas-tight glass syringes can be used, as well as cost efficient disposable syringes, with filling volumes between 100 μl and 3000 μl.

For use with glass syringes, stainless steel needles as well as stainless steel needles with PTFE coating are available. For use with the disposable syringes, disposable needles are also available.

Hydrophobisation kit for dosing needles

For a proper pendant drop evaluation and an easy placement of drops for the sessile drop method, wetting of the outer needle surface should be avoided. The hydrophobisation kit contains a specially formulated coating liquid, which can be used to treat needles before use. After treatment, the needle surface is highly hydrophobic and unwanted wetting is less likely.

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