Microfluidic electric impedance flow cytometry (IFC) chips have strong advantages over the traditional flow cytometry system because they are self-contained, disposable, economic in reagent consumption, and easier to operate. However, the throughput, sensitivity, and simplicity of the microfluidic IFC chips are inversely related to one another, and their reported impedance-based cell differentiation capability is in general limited. In this paper, we designed a sheath-less microfluidic IFC chip with a constriction structure between the detection electrodes to enhance the particle sensing performance, and built the entire sensing system around it, including the sensing circuit and data processing software. The measurement of the volume, limit of detection (∼3 μm), coefficient variation (6.83%) and other characteristics of the device was performed using the standard polymer beads. This sheath-less polydimethylsiloxane microfluidic device had a simple structure, which could maintain a single-cell sequence flow at the detection area, and displayed high signal-to-noise ratio (23.5–32.6 dB) and low coincidence ratio signals for further analysis. The throughput of the chip for single-cell screening can reach up to 172 cells per s, and thus, 10 000 cells could be analyzed in a few minutes for statistical analysis. Moreover, the electrical conductance and susceptance were found to be good at differentiating the bead/cell sizes and membrane/surface characteristics of cells/beads, respectively. These parameters were used to classify the population of a large amount of drug-treated cells (>10 000 cells per sample), displaying good performance in distinguishing apoptotic/necrotic cells from live cells. The ratios of apoptotic, necrotic, and live cells analyzed using our system were consistent with the traditional flow cytometry results (R² = 0.9796). Along with the miniaturization of the electric sensing circuit, our system can be applicable for novel, compact and easy operative (single) cell analysis systems in the future.

Tuberculosis (TB), caused by infection with airborne Mycobacterium tuberculosis (MTB), seriously threatens human health and has become a public health problem of worldwide concern. To achieve effective control of TB, rapid and sensitive detection of MTB is particularly important. At present, the common detection methods for MTB cannot meet the requirements of speed, flexibility and portability simultaneously. In this work, a multichannel microfluidic chip was developed and packaged with an ultra-sensitive silicon nanowire field-effect-transistor biosensor. The fluid system was tested and optimized through simulation, and the best conditions were determined: the flow rate was 0.3 mL min⁻¹ and the flow direction was perpendicular to a silicon nanowire. A one-way valve, a switching valve and a peristaltic pump were combined to establish a biosensor detection system to realize the automatic detection of TB samples. Then we systematically explained the factors affecting simulated exhaled breath condensate (SEBC) collection, and established and optimized the method for collection of SEBC from the perspective of collection volume and biological activity. The best collection conditions were determined for a 5 mm pipe diameter at 0 °C, and a sufficient sample volume was obtained in only 2 minutes for microfluidic detection. Then, the actual application value of the established collection method was further evaluated. Volunteers were recruited and this method was used to collect their exhaled breath condensate to analyze the collection effect. The system detected MTB in SEBC with good sensitivity (∼4 × 10⁴ particles per mL). It is expected to be further integrated and miniaturized in the future to realize point-of-care testing.