If the RayDrop has been manipulated (for cleaning or maintenance) the four screws might not be tightened enough.
Use an allen key to tighten.
You can calculate a scale factor which will correct the measured flow-rate returned by the FLOW UNIT.The different FLOW UNIT models are calibrated to provide an accurate reading when used with the corresponding fluid, water or isopropyl alcohol.For the FLOW UNIT models XS/XL, only one single calibration for water is available. For the FLOW UNIT models S/M/L, two calibrations are available: Water and Isopropyl alcohol.The FLOW UNIT can be used to handle different fluids not originally calibrated for. When possible, select a standard calibration field that most closely matches your fluid.For example, water calibration can be used for water based solution and isopropyl alcohol calibration for hydrocarbons or oil. The calibration can be selected and switched in the software.In order to obtain accurate flow-rates for alternative fluids, it is necessary to use correction factors (scale factor), to convert the displayed value into the actual value. The scale factor can be added in the software. Adding the scale factor ensures that the flow sensor reading is now accurate for the target fluid.
With the XS FLOW UNIT, the diameter of the capillary is small: 25 µm, so depending on the size of your system, you may need to push your fluids harder to obtain a given flow-rate. Then the maximum pressure drop between the sides of the XS FLOW UNIT model at maximum flow-rate is 0.8 bar.
Yes, we recommend filtering all solutions before starting your experiment. The presence of dust can block the nozzle.
For some fluid controllers, the settling-time may be long. For this reason, the transition phase after an order change in the fluid controller takes much longer, depending on the nature of the fluid controller. Visit us on www.fluigent.com for further information.
Some fluid controllers are unable to limit the fluctuations of the flow-rates around a mean ordered value because of the mechanical actuation they use. How to connect tubing to the FLOW UNIT models Therefore, the flow-rate within your system can be an imprecise response to the fluid controller. Visit us on www.fluigent.com for further information.
Make sure that all tubing is well flushed before connecting the RayDrop.
FLOW UNIT models are highly sensitive and should be properly cleaned to always maintain high performance. With proper care and maintenance, the FLOW UNITs can last many years. No cleaning or improper cleaning may leave deposits on the internal capillary wall which could result in measurement deviations and even clogging. Cleaning the sensor after use and before storing the device for a long period of time should prevent the sensors from any damage.Do not allow the sensor to dry with media in the capillary tube without flushing clean first. Also try to avoid letting the filled sensor sit for extended periods (depending on your liquid).Before storing the sensor, always drain of fluid, flush with cleaning agent, blow out, and dry the capillary.
Cleaning and flushing of the FLOW UNITs should consider the nature of the materials that were being pumped through them. Typically, one should select a cleaning solution that is safe for the FLOW UNIT (the inside surface) and the rest of the set up but yet will dissolve the type of samples that were in contact with the surface.For FLOW UNIT XS, S and M, fluids have to be compatible with PEEK & Quartz glass.For FLOW UNIT L and XL, fluids have to be compatible with PEEK & Borosilicate glass.
The following steps are recommended for water-based solutions, in the right order:• Rinse all your system with water.• Clean the FLOW UNIT with a non-foaming detergent.The detergent needs to be compatible with FLOW UNIT, the rest of your set-up (microfluidic chip, especially) and fluids used during your experiment.• Remove all the contaminants thanks to a disinfectant (for example, Javel bleach).• Rinse the Javel bleach (or the selected disinfectant) with water.• Rinse all you system with isopropanol. Thanks to this final step, you won’t leave any trace on your Flow Unit.• Then, sensor yellow plugs must be installed for storage
It is important to clean the RayDrop after each experiment in order to prevent clogging.
Refer to the good practice guide for the detailed procedure.
Integrate the FLOW UNIT to the microfluidic system with the dedicated tubing & fittings.
For L or XL FLOW UNIT model:
For XS, S or M FLOW UNIT model:
Connect the USB cable between the computer and the Flowboard.
The green led is now switched on.
Then connect the FLOW UNITs to the Flowboard.
• Make a fresh 1% solution (10 grams per liter) in cold or warm water. If available, use warm water below 130F (55°C). For difficult soils, use very hot water (above 150F or 65°C) and use double the recommended amount of detergent.• Circulate solution slowly for at least 1/2 hour.• RINCE THOROUGHLY—preferably with running water.• Drying can affect residues and corrosion. Impurities from rinse water can be deposited during evaporation. To minimize this, Dry with techniques that physically remove rinse water from the substrate such as isopropyl alcohol final rinse.
The FLOW UNITS have to be plugged to either Flowboard or to FlOW EZ, which allows the communication between the FLOW UNITS and the computer.
In general, any cleaning by mechanical means should be avoided. Never enter the sensor flow path with sharp objects that could scratch the glass surface.
Furthermore, no abrasives or liquids containing solids that can grind the surface clean should be used. Anything that affects the glass wall will cause deviations in the measurement performance or permanently damage the sensor.
Strong acids and bases should also not be used to clean the sensor. Acids can sometimes be used in low concentration and at low temperatures. Before using the acid check how compatible it is with borosilicate 3.3 glass (Pyrex® or Duran®).
It is possible to add a filter in the fluidic path. As an example, you can find among Idex products, biocompatible precolumn filters (references A-355, A-356). These filters are designed for use with 1/16’’ OD tubing. You can choose either 0.5 µm (A-700) or 2 µm (A-701) frit version to filter particles from you flow path.
Working with multiple liquidsSwitching between multiple liquids can leave transient deposits in the form of liquid layers inside the glass capillary. This is especially common for insoluble liquids, but can happen even with miscible liquid combinations. For example, when IPA is followed by water in a sensor without drying in between, large offsets can be observed for hours after switching to water. If possible, dedicate a separate sensor for each different liquid to be measured. If not possible, use caution when switching media and clean properly.
Working with waterWhen working with water it is recommended not to let the sensor dry out. All salts and minerals in the water will deposit on the glass and are difficult to remove. Although salt solutions are particularly prone to problems, even clean water can still contain enough dissolved minerals to form a deposition layer. Flush with DI water on a regular basis to prevent build-up. If you still encounter problems, occasionally flush the sensor with slightly acidic cleaning agents.When working with water containing organic materials (sugars, etc.) microorganisms often grow on the walls of the glass capillary and form an organic film that can be difficult to remove. Flush on a regular basis with solvents such as ethanol, methanol or IPA, or with cleaning detergents to remove organic films.
Working with silicone oilsWhen working with silicone oil it is recommended not to let the sensor dry out. Silicone oils can be cleaned out using special cleaners. Check with your silicone oil supplier for cleaning agents compatible with glass surfaces.
Working with paints or gluesWhen working with paints or glues it is critical not to let the sensor dry out. Often, depositions of paints and glues cannot be removed anymore after they have dried. Flush the sensor with cleaning agents recommended by your paint or glue manufacturer that are compatible with glass. Ensure that you have found a good cleaning procedure before performing the first tests, and always clean shortly after emptying the sensor.
Working with alcohols or solventsUnlike most other fluids, alcohols and solvents are not critical and a short flush of isopropanol (IPA) is sufficient to clean the capillary walls.
Other liquids or applicationsIf uncertain about your application and how to clean the flow sensor, please contact FLUIGENT for additional support at email@example.com
Most of the times, flow-rate peaks represent air bubbles. In order to get a stable measured flow rate, you have to remove all the air bubbles into your set-up. To achieve this, flush your set up by applying a higher pressure until air bubbles disappeared. Besides, you own flow controller might not deliver a stable flow. Contact us for more information.
The following section explains how you can calculate this scale factor and shows an example with a fluorinated oil: FC-40.A method for providing a known flow-rate is required to work out the scale factor for the selected fluid. This could be a syringe pump, a peristaltic pump or a pressure regulator delivering fluid onto a precision balance with volume calculated from known density. Here is an example using MFCS™-EZ.Make a table that contains the time for each measurement, results from weighing scale, the flow-rate of the pump and the data measured by the FLOW UNIT. A minimum of 3 measurements is recommended for each flow-rate.The principle of the experiment is to inject the FC-40 through the desired FLOW UNIT model connected to the FLOWBOARD. Then simultaneously you record the flow-rate given by the software and you measure the weight of fluid you have collected over a chosen period of time. Knowing the density of the fluid, you are able to define the actual flow-rate.Note that if a peristaltic or a syringe pump is used, one has to wait until the target flow-rate is reached (settling times can be long) and to calculate an average flow-rate due to the pulsations.
You can find cleaning procedures in the FLOW UNIT cleaning procedure. Concerning specifically the XS FLOW UNIT, it may withstand pressures up to 200 bar, so is it possible to use high pressure or flow-rate pumps in case of clogging.
The FLOW UNIT sensors are already temperature compensated, so they work in a range of 10°C to 50°C. This can be useful if your device needs to fit within an incubation chamber.
Leaks can sometimes appear if the fluidic connectors are not tightened enough.
Check that all the connectors are attached firmly.
(Be careful not to over tighten or your tubing may be blocked by pinching)
Open the top plugs of the RayDrop.
Return to the RayDrop filling state.
Refer to the application note protocol.
• The flow-rate calculated by the FLOW UNIT is based on a temperature diffusion-advection measurement with the glass capillary. If your fluid is not pure water (or isopropanol) you first need to add a scale factor to calibrate your FLOW UNIT.• There might be a leak within your system. Please check if your system is completely tight before going any further.• This might be because of your screwed fitting. Please unscrew and then re-screw it.• Your fluid controller may not be as precise as the FLOW UNIT sensor.
As chemicals, can be used ethylacetate, ethanol or IPA. (The nozzle material is not compatible at long-term use with dichloromethane)
Yes the diameter of the capillary is small: 25 µm, so depending on the size of your system, you may need to push your fluids harder to obtain a given flow-rate. Then the maximum pressure drop between the sides of the XS FLOW UNIT model at maximum flow-rate is 0.8 bar.