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By capillary electrophoresis (CE) in miniaturized lab-on-a-chip devices, integrated DNA sequencing and genetic diagnostics have become feasible. We introduce a principle of parallel optical processing to significantly enhance analysis capabilities. In a commercial microfluidic chip, a plug of DNA molecules was injected and the DNA molecules were CE-separated with a high relative sizing accuracy of >99%. Through an optical waveguide inscribed by femtosecond-laser writing a laser was launched perpendicularly into the microfluidic channel. A photomultiplier collected the fluorescence signals from a small detection window with a limit of detection of ~8 DNA molecules. In our approach, different sets of exclusively end-labeled DNA fragments are unambiguously identified by simultaneously launching several continuous-wave lasers, each modulated with a different frequency, detection of the frequency-encoded signals at different fluorescence wavelengths by a single ultrasensitive, albeit color-blind photomultiplier, and Fourier-domain frequency decoding. As a proof of principle, fragments from independent human genomic segments, associated with genetic predispositions to breast cancer and anemia, are simultaneously analyzed in a single flow experiment. This novel method of modulation-frequency-encoded fluorescence excitation opens new opportunities in genetic diagnostics. It enables the identification of end-labeled DNA samples of different genetic origin during their electrophoretic separation, opening perspectives for intrinsic size calibration, malign / healthy sample comparison, and exploitation of multiplex ligation-dependent probe amplification.

We use direct femtosecond laser writing to integrate optical waveguides into a commercial fused silica lab-on-chip (LOC). We fabricate high quality waveguides intersecting the microfluidic channels and use them to optically address with high spatial selectivity their content. Fluorescence from the photoexcited volume is efficiently collected at a 90 degrees angle by a high numerical aperture fiber, resulting in a compact and portable setup. Our approach is quite powerful because it allows the integration of photonic functionalities, by simple post-processing, into commercial LOCs, fabricated with standard techniques. By taking advantage of the unique three-dimensional capabilities of femtosecond laser writing, more complex functionalities, such as splitters or Mach-Zehnder interferometers, can be implemented.

We use direct femtosecond laser writing to integrate optical waveguides into a commercial fused silica capillary electrophoresis chip. High-quality waveguides crossing the microfluidic channels are fabricated and used to optically address, with high spatial selectivity, their content. Fluorescence from the optically excited volume is efficiently collected at a 90 degree angle by a high numerical aperture fiber, resulting in a highly compact and portable device. To test the platform we performed electrophoresis and detection of a 23-mer oligonucleotide plug. Our approach is quite powerful because it allows the integration of photonic functionalities, by simple post-processing, into commercial LOCs fabricated with standard techniques.

Ultrafast laser writing of waveguides in glasses is a very flexible and simple method for direct on-chip integration of photonic devices. In this work we present a monolithic optofluidic device in fused silica providing label-free and spatially-resolved sensing in a microfluidic channel. A Mach-Zehnder interferometer is inscribed with the sensing arm orthogonally crossing the microfluidic channel and the reference arm passing over it. The interferometer is integrated either with a microchannel fabricated by femtosecond laser technology or into a commercial lab-on-chip for capillary electrophoresis. The device layout, made possible by the unique three-dimensional capabilities of the technique, enables label-free sensing of samples flowing in the microchannel with spatial resolution of about 10 microm and limit of detection down to 10(-4) RIU.

Durable K + -selective chemically modified field effect transistors (CHEMFETs) with functionatized polysiloxane membranes have been developed. Polysiloxane membranes of different polarity, i.e., with different amounts of (cyanopropyl)siloxane groups, incorporating a free or covalently bound hemispherand as the ionophore and free or covalently bound tetraphenylborate axons as ionic sites, were investigated for their performance as sensing membranes. The CHEMFETs based on polysiloxane with both ionophore and anonic site covalently attached to the membrane matrix showed K + responses within almost Nerstian slope in the range of concentration 10 -4 -10 -1 M in the presence of 0.1 M Na + (log k K,NA Pot =-3.2)