Fig. 5.

Microfluidic technologies for HIV diagnosis. Principles of diagnosis: (A & B) Immunoaffinity, (C) electrical impedance and (D) RT-PCR. (A) Captured CD3 + CD4 + lymphocytes were stained and counted automatically by the designed software. This device allows 100 × faster speed in identifying immuno-stained lymphocytes for HIV detection. Reprinted with permission from Alyassin et al. (2009). (B) Left panel shows the sequence of steps the sample undergoes as it moves through the equipment-free microfluidic device (m-chip). Right panel illustrates the various steps of the immunoassay. The reduction of silver ions on gold nanoparticle conjugated with specific antibodies for signal amplification, facilitating readout without the use of expensive optics. Reprinted with permission from Chin et al. (2011). (C) Whole blood is introduced and RBCs are lysed, leaving a supposedly pure population of white blood cells. Total number of lymphocytes is counted followed by capture of CD4 + and CD8 + lymphocytes with microposts. Differential electrical impedance signals of the cells provide information on the degree of contamination and number of target lymphocytes. Reprinted with permission from Watkins et al. (2013). (D) RT-PCR integrated into microfluidic channel. Top panel shows the schematic and the bottom panel shows the actual device. Valves are created to isolate different steps of the process such as incubation, reaction and detection. Reprinted with permission from Lee et al. (2008).