The fabrication of microarray chips
and the precise dispensing
of nanoliter to microliter liquids are fundamental for high-throughput
parallel biochemical testing. Conventional microwells, typically featuring
a uniform cross section, fill completely in a single operation, complicating
the introduction of multiple reagents for stepwise and combinatorial
analyses. To overcome this limitation, we developed an innovative
valved microwell array. Using ultraviolet (UV)-curing resin three-dimensional
(3D) printing, these multilayer configurations can be rapidly fabricated
through direct template printing and polydimethylsiloxane (PDMS) casting.
Each microwell incorporates a microvalve structure, truncating fluids
within the upper metering well and allowing transfer to the bottom
reservoir well under centrifugal force. Sequential operations enable
the introduction of multiple reagents, facilitating orthogonal combinations
for complex assays. We explored four types of valving methods: DeepWell,
Expansion, Bottleneck, and Membrane valve, each offering varying degrees
of design complexity, operational efficiency, robustness, and precision.
These methods constitute a versatile toolkit to accommodate a broad
spectrum of analytical requirements. Our innovative approach redefines
microwell architecture, direct manufacturing techniques, and stepwise
fluid dispensation in microarrays.