Lateral Flow

Lateral Flow Equipment for Product Development and Manufacturing

A typical lateral flow device includes a test strip and a plastic housing. The housing can consist of more than two pieces such as ports for sample, etc.

Test strips typically include five components:

  1. Plastic backing with adhesive and release liner
  2. Sample pad
  3. Conjugate pad
  4. Nitrocellulose membrane
  5. Wick/Absorbent Pad
  6. Cover layers over the composite device (in some cases)

Materials can be supplied in roll, sheet or strip formats. The membrane is already converted for lamination onto the plastic backing. The other materials can be converted to the correct widths for processing and lamination before or after reagents are processed.

Reagent Processing

Reagent processing steps typically include the following:

Membrane

Dispensing test and control lines onto the membrane can be done before or after lamination. The blocking reagent can be dispensed in parallel with the test and control or afterwards.

The dispensing can be done with master strips or in roll formats. The typical method of dispensing onto the membrane is in a strip format using XY tables with bare membrane before lamination or master strips where the membrane has been laminated onto the plastic backing. The strip length is typically 300-500 mm. The blocking reagent can also be dispensed using a third dispense channel in parallel with the test and control lines.

The same dispensing as described above can be done on a reel-to-reel system using a roll format where the membrane is unbacked or pre-laminated to the backing material.

Line dispensing can be done with a contact or non-contact dispensing system. The non-contact is preferable, as contact dispensing leaves a small indentation on the membrane surface that degrades the quality (CVs) of the dispensed line.

Conjugate and Sample Pads

Two pads are typically processed using impregnated sheet stock, followed by drying, cutting to width, and lamination to a backing card. Web materials can be impregnated with an in-line reel-reel machine.

Common problems with degraded CVs in the finished product have been greatly improved by combining quantitative dispensing with the reel-reel or XYZ dispensing platforms. The reagent is very accurately dispensed along the lamination direction so that at each cut the lateral flow strip will have the same volume of dried reagent.

Dispensing and Impregnation Products

BioDot provides a number of dispensing and impregnation options for processing lateral flow test strips formats that can be integrated into different platforms.

FrontLine HR has a flexible dispense tip that rides on the substrate surface with the dispensed fluid emerging from dragging tip. The fluid flow rate can be synchronized with motion to create a quantitative volume per unit length of reagent on the substrate surface.

FrontLine HR dispensing is ideal for printing lines on membranes and other substrates for Rapid Tests, Immunoblots and Biochips.

This proprietary, quantitative, non-contact technology couples the BioJet “Drop-on-Demand” valve with a high-resolution syringe pump.

The BioJet HR™ meters precise amounts of reagent, incorporating the benefits of non-contact dispensing and the ability to program exact drop volumes.

BioJet Ultra™ technology offers a true non-contact picoliter liquid handling and spotting solution with drop-on-demand capability.

The dispense platform can produce a single dynamic drop volume range of 100 pL to 1.0 nl, with CV’s typically less than 5%. It is compatible with a wide range of reagent types, including aqueous, organic, and cells. The platform can be optimized to work with a high dynamic range of viscosities without additives (up to 400 cP).

BioDot’s AirJet technology uses pressurized air to atomize fluid passing through the dispensing nozzle for non-contact, quantitative aerosol dispensing. This creates a quantitative spray format, in which a dot or line can be quantitatively generated on a continuous basis.

BioDot’s proprietary technology couples the dispensing nozzle with a high-resolution syringe pump to meter exact amounts of reagents. This process produces a precise and easy to use method for dispensing microliter quantities of fluids.

The µAirJet is an aerosol type of dispensing nozzle that uses pressurized air to atomize the fluid passing through the nozzle. The nozzle coupled with a syringe pump creates a spray format, in which a line or dot can be generated on a continuous basis.

The straightforward design makes the µAirJet easy to use, clean and maintain.

Dispensing and Impregnation Platforms

BioDot provides a number of reagent dispensing platforms that are designed for a combination of R&D and production activities. In both cases the same dispensing technology is used which allows for R&D validated processes to be efficiently transferred to the manufacturing environment.

Impregnation

Bulk impregnation of sheets in baths or in-line with the RR120 is available. The RR120 has an impregnation module for dipping web materials followed by drying. Neither of these options are recommended due to the basic non-homogeneous nature of these materials which leads to variations of dried reagent concentrations. This problem is eliminated by the use of quantitative dispensing of reagents as described above.

Tandem Pumps

For continuous dispensing (no pause of a pump to refill) a tandem pump configuration is used for both FrontLine and BioJet dispensing.

Patents

BioDot has international patents for the BioJet HR™, BioJet Ultra™, AirJet, as well as the use of solenoid and aerosol dispensed heads combined with the use of syringe pumps to achieve quantitative dispensing. BioDot’s additional patents include the use of the Tandem pump configuration, which eliminates delays and line distortions due to syringe refilling cycles. BioDot holds patents in the US, China and Europe.

The ZX1010 is a flexible XY motion/dispense system with a pneumatic Z-axis and fully programmable motion and dispense parameters.

The ZX1010 is designed for simultaneous dispensing or individually dispensing lines and dots.

Using the ZX1010 platform, a maximum of 4 AirJet HR, 4 BioJet HR, 4 FrontLine HR, or 4 PolyDrop dispensers can be configured. You choose the the type and number of dispensers on your system to meet your application needs.

The XYZ series systems are powerful production tools for rapid test development and manufacturing with a larger working deck than the smaller XYZ3060 platform.

The XYZ3210 is a flexible XYZ motion/dispense system, with a motorized Z-axis and fully programmable motion and dispense parameters. The XYZ3210 is designed for simultaneous dispensing or individually dispensing lines and dots.

Using this platform, a maximum of 4 AirJet HR, 8 BioJet HR, 8 FrontLine HR, or 8 PolyDrop dispensers can be configured. You choose the the type and number of dispensers on your system to meet your application needs.

The XYZ3060 system is a powerful production tool for rapid test development and manufacturing.

The XYZ3060 is a flexible XYZ motion/dispense system, with a motorized Z-axis and fully programmable motion and dispense parameters. The XYZ3060 is designed for simultaneous dispensing or individually dispensing lines and dots.

Using this platform, a maximum of 4 AirJet HR, 8 BioJet HR, 8 FrontLine HR, or 8 PolyDrop dispensers can be configured. You choose the the type and number of dispensers on your system to meet your application needs.

The Reel to Reel system is a series of modular components configured to support your web dispensing/coating application. The system is typically used with rollstock material and runs continuously.

For continuous dispensing BioDot’s proprietary tandem pump system deliver reagents so that the web does not have to stop moving when the pump refills.

BioDot’s AD2030 platform is specifically designed to support the high motion accuracy and precision of the BioJet Ultra dispenser. BioDot’s BioJet Ultra™ technology offers a true non-contact picoliter liquid handling and spotting solution with drop-on-demand capability.

Unlike other traditional piezoelectric dispensers, the BioJet Ultra’s piezoelectric actuator can be decoupled from the capillary, enabling the use of low-cost drop-in replacement capillaries.

Vision Inspection for Lateral Flow Dispensing Platforms/Bad Part Marking

BioDot provides a variety of automated camera vision solutions in order to increase reproducibility in manufacturing as well as reliability in part inspection.

Automating the inspection process can lead to a higher quality of product and increased yield as well.

Vision Inspection

XYZ & RR120

For production level systems such as the RR120, camera vision inspection is essential for high volume manufacturing while maintaining 100% inspection. BioDot offers two camera types for the RR120 system; a high-speed inspection system and a high-speed/high-resolution version.

On membrane-based materials, the standard high-speed camera system is capable of inspecting up to five dispense lines simultaneously at rates up to 100mm/s. The standard inspection package includes inspection of line position, line width, gaps, bulges, narrow/neck-down, satellites, and concentration. Additional tools may be added based on application-specific inspection requirements.

For fiber pad inspection of conjugate dispense, a high-resolution camera can be used to inspect line position, width, deviation, concentration, gaps, and spikes. Filters can be added to enhance image quality for different reagents and materials. The same inspection system is available for card-based XYZ style systems.

AD Series Systems & Ultra

The AD series system’s vertical camera looks directly at the nest for device positioning, calibration, fiducial inspection, and pre/post dispense analysis. Controlled by BioDot’s graphical user interface, the vertical camera allows for the ultimate user-friendly experience with its simple “click to move” features.

AD Series Ultra systems consist of two cameras; (1) vertical camera looking down at the nest and (1) horizontal camera to capture dispensed drops in flight. The vertical camera has all of the capabilities as other AD series systems. The horizontal camera, unique to the Ultra set-up, allows users to capture individual drops in flight, providing real-time analysis of drop size, morphology, and velocity.

Lamination

Lamination can be performed using a manual batch process or a fully automated in-line system.

The LM5000 Clamshell assembles a lateral flow assay comprised of multiple materials onto an adhesive backing. It contains top and bottom vacuum nests to hold strip materials in place and is operated manually.

Standard or customized nest inserts are available and are easily interchangeable so that multiple assay designs can be laminated.

The LM9000 Continuous Laminating System provides continuous lamination of materials onto a plastic support backing with adhesive. Typical applications would be lamination of rapid diagnostic test strips or urine dip sticks.

Slitting, Cutting and Bottling

The CM5000 Guillotine Cutter is a robust and fully automatic system that provides high quality precision cuts. Hardened and coated steel blades improve ejection of cut strips and reduce glue build up.

Cut widths and quantities are easily programmed through a handheld terminal. Programs may be stored for system reference in development or manufacturing environments.

RS5000

The RS5000 is a web fed system where processed web material is slit into a number of thinner webs for subsequent lamination on backing cards for lateral flow, dipstick and other such devices. The machine consists of a feed reel followed by a set of individual rotary blades spaced at the desired cut web width.

The individual slit webs are then rewound onto hubs for transfer to a lamination machine. Examples would slitting sample and conjugate pads that have previously impregnated for final assembly.

Bottling Test Strips

The custom built Bottling System is designed to take either master cards or reel feed of the final laminate into the cutting of test strips for bottling. The master cards are magazine fed while the reel feed is using a large diameter reel to feed the laminate to a guillotine cutter with leading edge sensor and bad mark sensor.

The leading edge sensor insures the width of the cut strips which are dropped to a conveyor which sends the good strips to a bottling station. The final laminate is both inspected at the dispensing station for quality of dispensed lines and at the lamination machine for correct placement of individual layers.

The final laminate then portrays a combination of bad part markings which are recognized by the bad mark sensor on the cutter. Bad parts are removed at the cutter station and only passed parts go to the bottling process. The individual bottles are manually placed with and removed with manual placement of the bottle cap.

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