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• SIMPLE Chip (Microfluidic Chip with Vacuum-based Propagation)

SIMPLE Chip (Microfluidic Chip with Vacuum-based Propagation)

Self-powered integrated microfluidic point-of-care low-cost enabling (SIMPLE) chip

Portable, low-cost, and quantitative nucleic acid detection is desirable for point-of-care diagnostics; however, current polymerase chain reaction testing often requires time-consuming multiple steps and costly equipment. We report an integrated microfluidic diagnostic device capable of on-site quantitative nucleic acid detection directly from the blood without separate sample preparation steps.

https://advances.sciencemag.org/content/3/3/e1501645

Demonstrates multiplexing and propagation

Device Setup

Fig. 1 (A) The simple operation protocol requires minimal handling and no external pumps or power sources. Users may simply drop blood/amplification reagent mix into the inlet and then the chip performs automatic sample preparation. (B) The chip is then incubated on a reusable heat pack, and end-point isothermal digital amplification of nucleic acid is done (RPA). Scale bar, 2 mm. (C) Dye-loaded chip for visualization of microchannels. Red shows fluidic channels. Blue shows the main vacuum battery system. Green shows the auxiliary vacuum battery system. (D) Digital microfluidic patterning enables reagent patterning with common laboratory equipment. Left: After chip bonding. Right: Amplification initiator concentrated asymmetrically using a microapex stencil (see fig. S3 for details). Scale bars, 100 μm (black) and 1 mm (yellow). (E) Side view of the digital plasma separation design, which removes blood cells via sedimentation and skims plasma into dead-end wells for digital amplification. (F) The vacuum battery system frees the chip from external pumps or power sources for pumping. Vacuum is prestored in the large “battery” voids. Fluid is pumped by slowly releasing the prestored vacuum potential via air diffusion through lung-like structures.

Equipment Used + Workflow

A 2-layer PDMS chip is fabricated with microwells, a microcliff structure (useful for blood plasma separation), channels, vacuum batteries (punch holes in the bottom chip that become vacuum voids after keeping in -95kPa overnight), and is stored in a vacuum pouch for use.

The vacuum working is given in movie:

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https://advances.sciencemag.org/highwire/filestream/194472/field_highwire_adjunct_files/4/1501645_movie_S4.mov

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The Amplification initiator is pre-patterned on the top of each microwell and Blood + RPA mix is filled into each well using the vacuum-battery driven flow. The chip is incubated on a chemical heating pack and then fluorescence is used to detect nucleic acid.

Key Points

• Vacuum-Battery Driven Flow

• Chip made for Multiplexing

• Cons: No sample prep/extraction, no portable detection method