Protein Crystallization Chip

Dynamic counter-diffusion and dialysis crystallization screening across an integrated clamped semi-permeable membrane.

Cross-polarised optical micrograph from bottom window: birefringent lysozyme crystals grown under counter-diffusion across clamped membrane.

Material	3D-printed polymer, cellulose hydrate membrane, PMMA, anti-evaporation tape, transfer adhesive
Method	Mechanically clamped 3D-printed blocks over dialysis membrane, with lower 500 µm channel sealed via laminated optical PMMA base
Min feature	500 µm channel width
Idea to tested device	4 days

THE WORKFLOW

Crystallization screening is traditionally slow, consumes large volumes of scarce target protein, and relies on static well plates where chemical conditions cannot be adjusted mid-run. Dialysis-based microfluidics decouples the protein sample from a continuously flowing precipitant, allowing dynamic condition gradients without manual pipetting.

HOW IT WAS BUILT

The consumable is built as a hybrid 5-layer assembly. The upper conical microwell block and the microfluidic flow cell were fabricated via high-resolution SLA 3D printing. A cellulose hydrate dialysis membrane is mechanically clamped between the two blocks, creating an immediate, leak-free seal without liquid adhesives that could foul or clog the active pore matrix.

The lower 3D-printed flow cell contains a 500 µm wide fluidic channel with integrated fluidic inlet and outlet. To provide optical clarity for bottom-view inspection, the open lower channel is sealed by laminating an optically clear PMMA base plate using a transfer adhesive. Finally, the upper microwells are sealed with an anti-evaporation tape to minimise vapor loss over hours of continuous screening.

Assembled 3D-printed protein crystallization cartridge next to the 10 mm glass scale disc Assembled 3D-printed crystallization cartridge alongside the 10 mm signature glass disc: upper conical microwell block mechanically clamped over the dialysis membrane onto the lower perfusion flow cell with an optically clear PMMA base.

EXPLODED 5-LAYER ARCHITECTURE Adhesive-free membrane clamping

Optically Clear Adhesive Seal Top anti-evaporation tape cover

Seals conical microwells to minimise vapor loss and prevent sample drying during screening

3D-Printed Upper Well Block 4 conical protein microwells

Concentrates scarce protein solution directly onto the underlying membrane aperture

Cellulose Hydrate Membrane Semi-permeable dialysis interface

Mechanically clamped between blocks for dynamic salt and precipitant exchange without glue fouling

3D-Printed Microfluidic Flow Cell Inlet → 500 µm channel → Outlet

Perfuses precipitant beneath the membrane with open bottom routing for optical access

Optically Clear PMMA Base Laminated optical bottom window

Laminated to the 3D-printed flow cell to seal the 500 µm channel and enable bottom-view cross-polarised microscopy

BENCH CHARACTERIZATION

Validated using a lysozyme and NaCl model counter-diffusion system. Dynamic exchange across the cellulose hydrate membrane drives gradual supersaturation inside the microwells. Birefringent protein crystals were successfully grown and optically verified through the bottom viewing window under cross-polarised microscopy within hours.

HOW THIS APPLIES TO YOUR DEVICE

If your workflow requires dynamic dialysis, barrier tissue models, or tangential flow filtration (TFF), integrating delicate semi-permeable membranes into rigid cartridges is notoriously prone to glue fouling and leakage. This architecture proves that membranes can be mechanically clamped and sealed with anti-evaporation tapes in days. The geometry, chamber depths, well counts, and optical inspection windows can be tailored in biocompatible PMMA or 3D resins to match your exact assay protocol and microscope stage.