Micro-vibrational erythrocyte sedimentation rate (ESR) for sensitive measurement of erythrocyte aggregation

The erythrocyte sedimentation rate (ESR) can act as a useful index of nonspecific disease activity in the diagnosis of inflammatory conditions. However, there are several drawbacks, including long time measurement. To promote ESR tendency, a micro-vibrational erythrocyte sedimentation rate (MV-ESR) was proposed. By controlling the profile of injecting flow rate into blood sample, air between the syringe pump and bottom of blood column was compressed and released. Micro-vibration (MV) is simple reciprocating flow including motion in both positive and negative directions in a line. It is determined as the edge of the interface between top of blood column and air is pinned under the pressure wave. From that, shear rate generated by determined MV is from 0 to 10^–2 (s⁻¹) in this study. Extremely low shear conditions may enhance the probability of erythrocyte aggregation formation. During measurement, a meniscus of separated plasma and sedimented erythrocytes was recorded using a camera. For validation of the proposed MV-ESR method, the effects of hematocrit as well as the frequency and amplitude of flow in the sedimentation tube were investigated. To quantify the enhancement of MV-ESR, the area of relative gradient (A_RG) based on a relative gradient of 1 was used. When MV with a maximum flow rate of 1 mL/min and a period of 100 ms was produced until 15 min, MV-ESR exhibited the best performance. Then, the proposed technique was used to diagnose the ESR difference between a normal and periodontitis patient. The characteristic time (λ_ESR), indicating the degree completion of the erythrocyte sedimentation, of the periodontitis patients was lower than that of the control. Based on the experimental demonstrations, λ_ESR of the MV-ESR method has significant potential in the diagnosis of inflammatory conditions and prognosis of non-inflammatory conditions.