Lensless imaging for point-of-care testing.

We show a platform that merges a microfluidic chip with lensless imaging for CD4(+) T-lymphocyte counting at resource-limited settings. To capture CD4(+) T lymphocytes, anti-CD4 antibody was immobilized on a microfluidic chip. The captured cells were detected by a charge coupled device (CCD) sensor using lensless shadow imaging techniques. Gray scale shadow images of captured cells on the chip (24 mm x 4 mm x 50 mum) were enumerated in three seconds using an automatic cell counting software. The device achieved 70.2 +/- 6.5% capture efficiency, 88.8 +/- 5.4% capture specificity for CD4(+) T-lymphocytes, 96 +/- 1.6% CCD efficiency, and 83.5 +/- 2.4% overall platform performance (n = 9 devices). This integrated platform has potential for point-of-care testing (POCT) to rapidly capture, image and count specific cell types from unprocessed whole blood.