Microfluidic structures for flow cytometric analysis of hydrodynamically focussed blood cells fabricated by ultraprecision micromachining

Abstract

We present three-dimensional microfluidic structures with integrated optical fibers, mirrors and electrodes for flow cytometric analysis of blood cells. Ultraprecision milling technique was used to fabricate different flow cells featuring single-stage and two-stage cascaded hydrodynamic focusing of particles by a sheath flow. Two dimensional focussing of the sample fluid was proven by fluorescence imaging in horizontal and vertical directions and found to agree satisfactorily with finite element calculations. Focussing of the sample stream down to 5 microm at a particle velocity of 3 m s(-1) is accessible while maintaining stable operation for sample flow rates of up to 20 microL min(-1). In addition to fluorescence imaging, the micro-flow cells were characterised by measurements of pulse shapes and pulse height distributions of monodisperse microspheres. We demonstrated practical use of the microstructures for cell differentiation employing light scatter to distinguish platelets and red blood cells. Furthermore, T-helper lymphocytes labelled by monoclonal antibodies were identified by measuring side scatter and fluorescence.

Review Article: Recent advancements in optofluidic flow cytometer

“…Offthe-shelf fiber optics are readily integrated into microfabricated devices. [35][36][37][38][39] Frequently this is accomplished by the use of a fiber sleeve, 35,[37][38][39][40][41][42][43] which guides fiber insertion to correctly position the fiber ͑see Fig. 6͒.…”

Miniaturized flow cytometer with 3D hydrodynamic particle focusing and integrated optical elements applying silicon photodiodes

“…Flow cytometry based on optical inspection techniques (Shapiro 2003) has been successfully used for many years due to its distinct advantages in terms of detection sensitivity, versatility, and excellent reliability (Huh et al 2005;Ateya et al 2008;Zhang et al 2009). It offers a wide variety of detection platforms [e.g., fluorescence illumination: Tung et al (2004), Bernini et al (2006), Malic and Kirk (2007), Wu et al (2008), Fu et al (2008); extinction: Fu et al (2004), Kummrow et al (2009); and scattering measurements: Wang et al (2004), Golden et al (2009), Chen and Wang (2009)] to inspect relevant sample parameters. A suspension of particles or cells is introduced into a configurable fluidic system where they are hydrodynamically focused to significantly increase the detection sensitivity.…”

Analysis of a laminar-flow diffusional mixer for directed self-assembly of liposomes

“…19 Hydrodynamic focusing forms an integral part of a typical laminar-flow diffusionmixer. 5,6,13,[20][21][22][23] The technique uses co-flow of miscible focusing solution to confine a solution to a sub-cross-section of a channel. Groups develop various hydrodynamic focusing architectures for mitigating sticking to channel walls, 6 ensuring rapid mixing, 13,24,25 and ensuring uniform residence time among the focused solutes.…”