应用于类球体细胞电旋转分析中的介电参数求解算法

Dielectric parameter solving algorithm in electrorotation analysis of spherical cells

根据薄膜理论建立了一种面向类球体细胞的单壳介电模型,分析了细胞在电旋转静流场中的受力,并由旋转力矩和斯托克斯流体阻力矩平衡原理,推导得到细胞各层介电参数方程组.利用引入压缩因子的粒子群优化算法求解细胞的介电参数,并讨论了压缩因子的变化对求解结果的影响.以Granulocytes白细胞为例进行算法验证,得到细胞膜的电导率和相对介电常数分别为7.25μS/m和10.3,细胞质的电导率和相对介电常数分别为0.487 S/m和136,且压缩因子的变化仅影响各组解的搜索概率,加速系数为2.015时所需解的搜索概率达到最高值.算法结果与白细胞介电参数的经验数据相吻合,表明该算法具有较高的精确性和稳定性.

A dielectric model with single concentric shell of spherical cells is established based on film theory. The forces of the cells in a static flow field under the action of electrorotation are ana- lyzed, and the force equilibrium equations are derived to obtain dielectric parameters of each shell by the balance of the rotating torque and the Stokes fluid drag torque. Then, the particle swarm optimi-zation algorithm improved with the constriction factor is used to solve the equations. The influence of the change in the constriction factor on the solution results is also discussed. This algorithm is val- idated with Granulocytes as an example. The calculated membrane conductivity, membrane relativepermittivity, cytoplasm conductivity and cytoplasm relative permittivity are 7. 25 μS/m, 10. 3, 0. 487 S/m and 136, respectively. Besides, the change in the constriction factor just affects the search probability of each solution, and the search probability needed gets the highest value with theacceleration factor of 2. 015. The calculated results are consistent with the empirical data, showing that the proposed algorithm can obtain high accuracy and stability.