Lateral flow assays (LFAs) use capillary flow of liquids for simple detection of analytes. While useful for spontaneously wicking samples, the capillary flow inherently limits performing complex reactions that require timely application of multiple solutions. Here, we introduce a technique to control capillary flow on paper by imprinting roadblocks on the flow path with water-insoluble ink and using the gradual formation of a void between a wetted paper and a sheath polymer tape to create timers. Timers are drawn at strategic nodes to hold the capillary flow for a desired period and thereby enable multiple liquids to be introduced into multistep chemical reactions following a programmed sequence. Using our technique, we developed (i) an LFA with built-in signal amplification to detect human chorionic gonadotropin with an order of magnitude higher sensitivity than the conventional assay and (ii) a device to extract DNA from bodily fluids without relying on laboratory instruments.

Extremely rare circulating tumor cell (CTC) clusters are both increasingly appreciated as highly metastatic precursors and virtually unexplored. Technologies are primarily designed to detect single CTCs and often fail to account for the fragility of clusters or to leverage cluster-specific markers for higher sensitivity. Meanwhile, the few technologies targeting CTC clusters lack scalability. Here, we introduce the Cluster-Wells, which combines the speed and practicality of membrane filtration with the sensitive and deterministic screening afforded by microfluidic chips. The >100,000 microwells in the Cluster-Wells physically arrest CTC clusters in unprocessed whole blood, gently isolating virtually all clusters at a throughput of >25 mL/h, and allow viable clusters to be retrieved from the device. Using the Cluster-Wells, we isolated CTC clusters ranging from 2 to 100+ cells from prostate and ovarian cancer patients and analyzed a subset using RNA sequencing. Routine isolation of CTC clusters will democratize research on their utility in managing cancer.

A monolithic 3D-printed microfluidic device integrated with stacked layers of functionalized leukodepletion channels and microfiltration for the negative enrichment of circulating tumor cells directly from clinically relevant volumes of whole blood.

No abstract

A typical microfluidic device sorts, captures or fractionates sample constituents by exposing them to discriminating microenvironments. Direct electronic acquisition of such manipulation by a network of integrated sensors can provide a fast, integrated readout, replacing otherwise required microscopy. We have recently introduced a sensor technology, Microfluidic CODES, which allows us to multiplex resistive pulse sensors on a microfluidic device. Microfluidic CODES employs a network of micromachined coplanar electrodes such that particles passing over these electrodes produce distinguishable code sequences. In this paper, we explain the design process to specifically generate an orthogonal digital code set for an efficient and accurate demultiplexing of the sensor signals. We also introduce an equivalent circuit model for a network of code-multiplexed resistive pulse sensors by utilizing the Foster-Schwan model and conformal mapping, to model dynamic cell-electrode interaction in a non-uniform electric field. Our results closely match with both experimental measurements using cell lines and finite element analysis. The coding and modeling framework presented here will enable the design of code-division multiplexed resistive pulse sensors optimized to produce desired waveform patterns to ensure reliable and efficient decoding.

A disposable magnetophoretic cytometer with a multiplexed electronic readout for quantitative membrane antigen profiling.

Membrane antigens are phenotypic signatures of cells used for distinguishing various subpopulations and therefore, are of great interest for diagnosis diseases and monitoring of patient in hematology and oncology. Existing...

Reliable and routine isolation of circulating tumor cells (CTCs) from peripheral blood would allow effective monitoring of the disease and guide the development of personalized treatments. Negative enrichment of CTCs by depleting normal blood cells ensures against a biased selection of a subpopulation and allows the assay to be applied on different tumor types. Here, we report an additively manufactured microfluidic device that can negatively enrich viable CTCs from clinically-relevant volumes of unmanipulated whole blood samples. Our device depletes nucleated blood cells based on their surface antigens and the smaller anucleated cells based on their size. Enriched CTCs are made available off the device in suspension making our technique compatible with standard immunocytochemical, molecular and functional assays. Our device could achieve a ~ 2.34-log depletion by capturing > 99.5% of white blood cells from 10 mL of whole blood while recovering > 90% of spiked tumor cells. Furthermore, we demonstrated the capability of the device to isolate CTCs from blood samples collected from patients (n = 15) with prostate and pancreatic cancers in a pilot study. A universal CTC assay that can differentiate tumor cells from normal blood cells with the specificity of clinically established membrane antigens yet require no label has the potential to enable routine blood-based tumor biopsies at the point-of-care.