Sepsis arises from infection and immune dysregulation. Neutrophils play a key role in its progression, yet existing clinical tools cannot simultaneously isolate these cells and measure their functional activity.

A research team from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences and the First Affiliated Hospital of Anhui Medical University has developed a microfluidic platform for label-free sorting and functional analysis of neutrophils in sepsis patients. Their study is published in Analytical Chemistry.

The researchers designed a two-part system. The first component, a cell-sorting chip (CS chip), can extract white blood cells from a small blood sample (≤50 μL) with high purity (>80%) and viability (>90%). The second, a deformation and chemotaxis chip (CD² chip), evaluates neutrophil motility by measuring deformation time (T_D) and migration time (T_M). Integrated into a single platform, the system automates both sorting and motility assessment in just 30 minutes.

Optimization through structural design and COMSOL simulations ensured gentle flow conditions, preserving cell integrity. Experiments confirmed stable chemical gradients, reproducible sorting performance, and consistency across operators. In clinical tests, neutrophils from sepsis patients showed markedly impaired motility, with prolonged T_D and T_M compared to healthy individuals.

The researchers also introduced a Neutrophil Motility and Function Index, combining T_D and T_M into a single parameter. This index achieved excellent diagnostic accuracy and correlated strongly with standard clinical markers.

According to the team, the new system provides a rapid, label-free, and dynamic method for assessing immune function, offering promising applications in early diagnosis, precision monitoring, and treatment optimization for sepsis patients.