The frequency at which the induced particle dipole goes to zero, known as the crossover frequency, is highly dependent on the surface conductance of the particle. We have shown previously that DNA hybridization on the surface of a 100 nm functionalized silica particle leads to detectable surface conduction changes which make it possible to detect DNA hybridization reactions by simply measuring changes in particle suspension crossover frequency (cof).
In this work we utilize the above mentioned phenomena to detect the malaria species Plasmodium falciparum in an infected red blood cell suspension. Additionally, it is shown that DEP can not only be used as a genetic sensor, but can also be utilized to optimize the conditions for which particle surface hybridization takes place. By varying the particle surface concentration of oligonucleotide it is shown that a suspension cof can determine the optimal surface concentration for which hybridization can occur. Additionally, since the cof is sensitive to the length of the DNA strand, we also demonstrate the ability to identify different species of malaria based on differences in their PCR amplified DNA lengths.