Question 1

How do I choose between label-based and label-free sorting?

Accepted Answer

The choice follows the target population. When a reliable surface biomarker distinguishes the cells, affinity capture or fluorescence triggering gives high specificity. When no clean marker exists, or when labels would perturb downstream function, physical contrast in size, deformability or dielectric response becomes the practical route, usually at the cost of specificity.

Question 2

Which performance metrics must a sorting thesis report?

Accepted Answer

Purity, recovery, enrichment factor and throughput belong together, because improving one typically degrades another. Define each with the counting method used, state the input population composition, and give viability after sorting. A single headline number without its trade-off partners is the most common weakness examiners identify.

Question 3

What fabrication route suits early device iterations?

Accepted Answer

Soft lithography with elastomer casting from a photoresist master remains the fastest route for iterating geometry, since a new design can be tested within days. Once the geometry stabilises, thermoplastic moulding or glass bonding improves reproducibility, optical quality and solvent tolerance, and better represents how a manufactured device would behave.

Question 4

How is clogging and fouling controlled during long runs?

Accepted Answer

Upstream filtration, careful sample preparation and buffer additives that reduce cell aggregation address most blockages. Surface passivation with protein blockers or polymer coatings limits non-specific adhesion, and channel geometry can be designed to avoid stagnation zones. Report run duration, sample concentration and failure frequency rather than only successful runs.

Question 5

How should a device be benchmarked against established methods?

Accepted Answer

Run matched samples through the chip and through a reference method such as flow cytometry or magnetic separation, using the same gating definitions and counting approach. Spiked mixtures with known ratios establish accuracy at defined abundance, and biological samples across several donors test whether performance holds outside idealised conditions.

Question 6

What evidence shows sorted cells remain functional?

Accepted Answer

Viability staining immediately after sorting is a minimum. Stronger evidence comes from function retained downstream, such as proliferation, differentiation capacity, cytokine response or intact transcriptional profiles by sequencing. Comparing shear exposure between the chip and a conventional sorter supports claims that the gentler route preserves fragile primary cells.

Question 7

Do rare-cell applications need different validation?

Accepted Answer

Yes. At very low target abundance, purity becomes sensitive to a handful of contaminating events, so counting statistics and confidence intervals matter more than point estimates. Validation usually requires spiking experiments across several orders of abundance, together with sufficient replicate runs to characterise variability at the lowest concentration tested.

Biotechnology

Biotechnology

Research Frontiers in Microfluidic Cell Sorting Technologies