To gain an understanding of the application requirements our fluidics experts ask questions such as:

• Is the fluid stable of temperature?
• Does the viscosity change over time?
• Is the viscosity particularly high or low?
• Will evaporation change concentrations?
• Does the fluid have unique storage requirements?
• Does it require mixing?
• How should a user interact with the fluid?

With an understanding of the fluidic requirements, our engineers can then go about the process of selecting, customizing or developing components, connections and workflows that meet the design need.

Typically, fluid needs to be stored either on-consumable or on-machine for any diagnostic device. There are a many factors that guide the implementation of a storage solution, some of which are:

Temperature – Is refrigeration or heating required?
Volatility – Does the fluid pose a fire risk or is evaporation a major concern?
Time-based effects – Will viscosity change, or will crystallization occur?
Volume – Are the volumes in the <1mL range and is wastage a commercial concern?
Throughput– How much and how often will the fluid be accessed?
Uesr interaction – How are the fluids maintained or replaced?

Invetech’s fluidic experts have designed fluid storage solutions from large bulk containers that last for many days in a high to medium throughput setting, user-accessible bulks that contain medium value volatile reagent and low-volume extremely high value reagent containment and sensing systems that allow for the most precious of reagents to be used sparingly with minimal waste.

There is a wide range of options for moving fluid throughout your instrument to execute your assay. From simple pipetting systems to fully integrated fluidic systems that supports complex and sensitive end-use components.

Invetech has designed and put into production many different instruments with a range of fluid transport implementations. For example, for a medium throughput histology auto-stainer we designed a fully integrated fluidic system that managed volatile, non-volatile, crystalizing and self-degassing fluids. We utilized many different types of valves, pumps, tubing and sensors to ensure that each fluid was stored and transported correctly so that the staining results were world-leading.  For a point-of-care immunology diagnostic device that ran highly sensitive chemiluminescent assays from a single open-well input consumable, we implemented a miniaturized yet incredibly capable pipetting system.  For our cell therapy applications, we have designed multiple types of fully enclosed, aseptic tube-sets that are acted upon externally by active pumping and sensing devices.

Blending, dissolving, emulsifying or suspending are just some of the many mixing methods that you may require when designing fluidic processes. Implementing these methods into an automated device can be achieved using a variety of technologies from simple stirring mechanisms all the way through to more advanced systems such as ultrasonic mixers or dedicated microfluidic mixing chips.

The challenges presented in mixing often focus on three areas:

• Homogeneity: Hard to mix fluids or fluid-solid suspensions may require more powerful mixing systems or variable workflows in order to achieve the desired results.

• Cross-contamination: Particularly prevalent in micro-fluidic applications, ensuring that mixing does not result in contamination of subsequent assay steps due to splashing, pumping or thermally driven flow is a risk that is controlled via geometric changes, active components such as valves or through workflow adjustments.
• Damage: Over-mixing may cause damage to the assay fluids or contained media such as cell or DNA fragments. Phenomena such as lysing of biological components may occur. Selecting the appropriate mixing method and apply a suitable amount of energy over time will minimize or eliminate damage effects.