Study on the Protective Effect of Low‑Stress Damping Pipette Connector for Fragile Oral Samples

Abstract

Oral samples consist of primary gingival cells, saliva, and dental plaque microbial communities, featuring complex compositions. Their cells and microorganisms are highly sensitive to fluid shear force. When samples are directly aspirated and dispensed by conventional pipettes, high‑velocity liquid flow generates considerable fluid shear stress, which leads to rupture of gingival cells and disturbance of microbial community structure, thereby confounding subsequent experimental outcomes such as cell culture and 16S rRNA sequencing. Commercially available slow‑aspiration pipette connectors achieve flow‑rate damping via tiny central capillary orifices. However, such orifices are prone to clogging when handling high‑viscosity samples rich in mucin like saliva, limiting their applicability to pre‑processing of oral samples. In this paper, a low‑stress damping pipette connector with labyrinth‑type flow channels is designed. Equipped with widened circuitous labyrinth channels and bottom shunt guide teeth, the device buffers aspiration‑dispensing flow velocity while avoiding clogging risks posed by high‑viscosity saliva samples. Its protective performance for fragile oral samples is evaluated through fluid impulse calculation, cell‑damage control experiments, and anti‑clogging simulation tests for high‑viscosity samples. The results demonstrate that the proposed device markedly mitigates fluid impact during pipetting and alleviates mechanical damage to primary gingival cells, while preserving the community diversity of oral microorganisms. The entire device is autoclavable, compatible with existing commercial pipettes, and requires no instrument modification for operation. It provides a low‑cost hardware solution for standardized pre‑processing of oral samples.