Counterflow Dielectrophoresis for Trypanosome Enrichment and Detection in Blood

Abstract

Human African trypanosomiasis or sleeping sickness is a deadly disease endemic in sub-Saharan Africa, caused by single-celled protozoan parasites. Although it has been targeted for elimination by 2020, this will only be realized if diagnosis can be improved to enable identification and treatment of afflicted patients. Existing techniques of detection are restricted by their limited field-applicability, sensitivity and capacity for automation. Microfluidic-based technologies offer the potential for highly sensitive automated devices that could achieve detection at the lowest levels of parasitemia and consequently help in the elimination programme. In this work we implement an electrokinetic technique for the separation of trypanosomes from both mouse and human blood. This technique utilises differences in polarisability between the blood cells and trypanosomes to achieve separation through opposed bi-directional movement (cell counterflow). We combine this enrichment technique with an automated image analysis detection algorithm, negating the need for a human operator.

Rapid (<5 min) Identification of Pathogen in Human Blood by Electrokinetic Concentration and Surface-Enhanced Raman Spectroscopy

“…Based on the above scaling dependence equation, the importance of EHD relative to DEP increases for smaller particles while DEP becomes the dominated dynamics for manipulating bigger particles. The DEP force is approximately constant when the applied frequency is below/above the crossover-frequency ( cof ), but the magnitude of DEP force has a large difference near the cof 38. Besides, the magnitude of ACEO is also very sensitive to frequency of the applied voltage (eq.…”

Dynamic drag force based on iterative density mapping: A new numerical tool for three‐dimensional analysis of particle trajectories in a dielectrophoretic system

“…(7)- (9). (10) This dynamic drag force change is inversely proportional to the density of particles, as given below: (11) in which k density is the density scaling factor, the value of which varies depending on frequency and is empirically obtained as outlined in Supporting Information 3. The unit (m 3 ) of k density is necessary to attain a dimension-less scaling factor.…”

“…trophoresis are markedly diverse, and include sorting of suspended cells [4][5][6][7], determining cell viability [8], enrichment or depletion of target cells or cell products for detection [9], trapping cells for imaging purposes [10,11], and very recently for the controlled rotation and vibration of cells [12].…”

Lab-on-a-Chip Technologies for the Single Cell Level: Separation, Analysis, and Diagnostics

“…Some salient examples thereof are circulating tumor cells (CTC) of various types of cancer [1,[36][37][38], rare cells (e.g., sickle-cell variants of red blood cells) [39,40], parasites, like Plasmodium falciparum [1,7,10,11,[13][14][15][21][22][23]36,[41][42][43][44][45][46][47][48][49][50] and Trypanosoma spp. [8,44,[51][52][53][54][55][56][57] and even plant pathogens [26,58], as well as-after cells have been lysed-subcellular infection markers (e.g., DNA, RNA fragments) [10,11,22,43,[59][60][61][62]. Given the vast adaptability of microfluidics to any kind of single or multi-cellular assay [63], the ability to combine it with various light microscopy techniques…”