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.

Defect engineering of metal–organic frameworks (MOFs) has already found applications in gas adsorption, storage, and heterogeneous catalysis. However, the role of defects in determining electrical, optical, and mechanical properties of MOFs is yet to be explored. Herein, we demonstrate the white light emission properties of two defect engineered MOFs (UiO-66 and MIL-53­(Al)) through the encapsulation of lanthanide ions (Eu3+ and Tb3+). The defect sites are created by the use of a modulator (4-acetyl benzoic acid; AB) during the synthesis of MOFs. The color of the lanthanide functionalized UiO-66 could be tuned from white (UiO-66-AB) to green (Tb@UiO-66-AB), pale pink (Eu@UiO-66-AB), and yellowish-white (Tb/Eu@UiO-66-AB) when placed under a laboratory ultraviolet lamp (365 nm). Under the same conditions, the lanthanide functionalized MIL-53­(Al) showed color changes from blue (MIL-53­(Al)-AB) to cyan (Tb@MIL-53­(Al)-AB), pink (Eu@MIL-53­(Al)-AB), and white (Tb/Eu@MIL-53­(Al)-AB). The luminescence properties of all the lanthanide encapsulated modulated MOFs have been well studied. Notably, by varying the excitation wavelength, a close to white light was obtained for the Tb/Eu@UiO-66-AB material (λex = 340 nm; CIE coordinates (x = 0.3290, y = 0.3934)) and Tb/Eu@MIL-53­(Al)-AB (λex = 320 nm; CIE coordinates (x = 0.3204, y = 0.3873)). These observations indicate that lanthanide encapsulation at defect sites of MOFs allows more room for design and color tuning. The high thermal stabilities, good crystallinities, and tunable luminescence properties of MOFs reveal that these materials may have potential applications in white light emitting devices.

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