Optimized personnel flow with minimal contamination: development and validation of an air-barrier cleanroom for cell products processing

Introduction

Cell processing facilities for regenerative medicine require strict prevention of cross-contamination. However, the typically employed sealed, multi-room layout increases energy demands and capital costs due to heating, ventilation, and air-conditioning (HVAC), and restricts staff mobility. We devised a semi-open (SO) cleanroom that eliminated doors between the cell processing room (CPR) and adjoining corridor, while maintaining unidirectional airflow as a barrier. This study rigorously compared four interface variants—plain opening, wing walls, push–pull ventilation, and a conventional swing door—to verify whether operational flexibility can be achieved without compromising particle content performance at the CPR–corridor interface.

Methods

Computational fluid dynamics (CFD) simulations reproduced two connected rooms separated by a 900 × 2000-mm² opening, supplied at 23 m³/min (35 air changes per hour) constantly. Four interfaces were evaluated: plain opening, 100–500 mm wing-wall panels, push–pull ventilation adjusted to a 0.75 ratio, and a conventional swing door. A 1-m/s cross-draft emulated personnel transit. Identical full-scale mock-ups were built; particle image velocimetry (PIV) quantified airflow vectors, and optical counters logged 0.5-μm aerosols during 5-min exit and entry. The primary endpoints were the inflow particle concentration ratio across the opening and the cumulative adjacent-room transfer proportions.

Results

CFD showed all layouts leaked ≤0.011 %, with a 1 m/s walking draft, push–pull kept inflow below 0.05 %, halving 500-mm wing-wall performance and outperforming plain openings. The PIV confirmed significant differences in airflow velocity distributions under each condition in the case of the exit. The semi-open layout without doors showed a lower proportion of vectors pointing opposite to the forward direction than the conventional layout in both the exit and entry cases. Particle counts supported this: push–pull transferred 0.013 % of particles on exit, 32.8 % on entry, giving overall migration to the adjacent room of 0.0043 %.

Conclusions

The SO cleanroom concept suppresses fluctuations in particle content at the CPR–corridor interface while eliminating physical doors, enabling flexible personnel flow and obviating extra HVAC zones. Push–pull ventilation delivered the most robust containment against walking-induced disturbances, whereas the 500-mm wing walls offered a passive, power-free alternative with moderate protection. With worst-case inter-room transfers below 0.05 %, SO designs can rationally replace conventional door-sealed rooms, substantially reducing energy and construction costs in regenerative medicine manufacturing.