In the last two decades, microfluidic technologies have shown the great potential in developing portable and point-of care testing blood cell analysis devices. It is challenging to integrate all free-space detecting components in a single microfluidic platform. In this paper, a microfluidic cytometer with integrated on-chip optical components was demonstrated. To facilitate on-chip detection, the device integrated optical fibers and on-chip microlens with microfluidic channels on one polydimethylsiloxane layer by standard soft photolithography. This compact design increased the sensitivity of the device and also eliminated time-consuming free-space optical alignments. Polystyrene particles, together with red blood cells and platelets, were measured in the microfluidic cytometer by small angle forward scatter. Experimental results indicated that the performance of the microfluidic device was comparable to a conventional cytometer. And it was also demonstrated its ability to detect on-chip optical signals in a highly compact, simple, truly portable and low cost format which was perfect suitable for point-of-care testing clinical hematology diagnostics.
The optical signal on microfluidic chip is hard to be collected. To improve the excitation power and collection efficiency,
we introduced a simple, inexpensive fabrication method to increase the couple rate of optical fiber. This small element is
a polymer and air integrated microlens that can improve the optical signal detection. Compared to other established
protocols, this procedure allows a simple, miniaturizing and inexpensive microlens fabrication with high reproducibility.
The air microlens was produced by using direct lithograph of SU-8 resist to reduce the beam divergence of optical fiber.
Owing to its ability to achieve customized microlens for specific applications, this technique can be used in a variety of
applications, such as a blood cell counting system based on microfluidic chip.