Fast Response Implementation of Electroosmotic Stress Control Method in Microfluidic Chip

Stress response hysteresis behavior exists in the stress controlling by the electroosmotic effect. In this study, the response of microfluidic chip is investigated by modeling a three-dimensional resistive network, and the evolution of a number of randomly distributed viscous particles in the Polydimethylsiloxane (PDMS) matrix is calculated demonstrating that the change in the conductance of the microfluidic chip is determined by the amount of tunneled particles of solution in the reservoir. Besides, when the interval of agglomerated particles is below the cutoff distance of 150.58 nm, it has a wide range of the relative resistance rate of change. Therefore, the high sensitivity of the microfluidic chip is effectively obtained by adding PDMS matrix material particles to the conductive liquid to fully fill the spacing of the agglomerated particles. Moreover, by comparing the sensitivity and hysteresis of conductive liquids containing different proportions of KCl, it is proved that the conductive liquid containing 2 mol % KCl has the higher sensitivity and the lower hysteresis. On this basis, the corresponding stress control process is analyzed. It is proved that the stress response characteristic of microfluidic chip is proportional to the control voltage. Moreover, under the control of voltage with continuous waveform, by overshooting the control voltage and advancing the phase by π/12, the phase compensation of the unknown time loss in the control method is carried out to ensure that the stress response hysteresis is reduced. When the phase difference between the character of stress output and the waveform of input voltage is within 0.5 s, the character of stress output has ideal and stable waveform characteristic. Therefore, this study realizes the fast response in the process of stress regulation by electroosmotic effect, which provides the technical support and innovative application for precise stress control by the electroosmotic effect.