Spatially programmable deterministic lateral displacement for multi-stage microfluidic separation

Deterministic lateral displacement (DLD) is a widely used microfluidic technique for continuous size-based separation. However, a conventional uniform DLD array is characterized by a single critical diameter (D_c) fixed by its geometry, restricting its ability to fractionate complex samples containing multiple particle populations. Here we present a DLD platform that spatially programs the geometrically estimated D_c after fabrication by thermally modulating the pillar geometry along a single array. Two independently controlled Peltier elements establish a longitudinal temperature field that progressively changes the pillar diameter and inter-pillar gap, generating an estimated D_c(x) profile ranging from 4.7 to 19.2 μm within an array fabricated with uniform initial geometry. As particles traverse the array, size-dependent transitions between bump and zigzag migration modes occur at different positions, producing distinct cumulative lateral displacements and enabling sequential separation within a single device. Using the three-outlet architecture, the device further enables reconfigurable grouping of a four-component particle mixture into three outlet fractions by shifting the applied temperature window. Furthermore, the platform selectively isolated tumor cells, white blood cells, and red blood cells from diluted whole-blood samples spiked with MCF-7 cells. A descriptive assay indicated high post-processing viability of the MCF-7 cells. By enabling post-fabrication programming of the operating separation profile, this work demonstrates how the same physical array can be reconfigured for different separation tasks by changing the applied temperature window.