Microfluidic system for detectingmalaria-infected red blood cells using impedance measurementcoupled with electromagnetic force

Abstract

Malaria is one of the most life-threatened diseases caused by Plasmodium parasite. Malaria is preventable and curable, mainly due to the factor of time and management of the spread. In other words, a rapid detection with high accuracy will contribute to more effective treatment process. In this research, we introduced the new technique implemented microfluidics, dealing with the manipulation of blood cells using magnetic force, and impedance measurement measuring the signal changes of electrical impedance between a couple of electrodes. According to the distinct magnetic properties of normal red blood cells and malaria-infected red blood cells, the experiment was designed to compare the impedance of these two blood types at the symmetrical distance along two outlets. One of which used electromagnetic field to pull malaria cells to flow into more than the other. By the capability of distinguishing the signal resolution, the differentiation of changes in impedance would refer to discriminated percentage parasitemia of malaria. From the preliminary experiment, our microfluidic channel could divide similar number of beads and amount of fluid volume for both outlets. When we applied electromagnetic field on only the side near one outlet, the number of magnet beads on that side is greater than the other. Moreover, impedance measurement was tested with various plastic bead density which is at 2x105, 3x105, and 6x105 beads/ml in static test, and 6x105, 7.5x105, and 1.5x106 beads/ml in dynamic test. These results shared the same trend that the resistance was greatly increased, while the reactance was gradually increased when the density was increased. Similarly, we used normal mouse blood, 10% and 44% parasitemia malaria-infected blood to be our experiment samples in both static and dynamic test. The results showed that the difference of signal between normal mouse blood, 10% and 44% malaria-infected blood could be discriminated when we applied electromagnet at 15V and 24V. In case of 44% malaria-infected blood, significant change in resistance and reactance was found which specially increased in the outlet where magnetic force was not applied. When applied magnetic field, the outlet without the magnetic force had less infected blood cells and lower cell density that has two countering effects on the impedance in such a way that higher and lower resistance would be obtained, respectively. From our experiments, the results suggested the stronger influence of blood type on the impedance as the total resistance increases at this outlet. In the future, after the further development, we hope that the impedance different ratio would more precisely translate into the percentage parasitemia.