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We present a microfluidic surface-enhanced Raman scattering (SERS) sensor for rapid and label-free biomolecular detection. Our sensor design mitigates a common limiting factor in microfluidic SERS sensors that utilize integrated nanostructures: low-efficiency transport of biomolecules to nanostructured surface which adversely impacts sensitivity. Our strategy is to increase the total usable nanostructured surface area, which provides more adsorption sites for biomolecules. Specifically, a nanoporous gold disk (NPGD) array, a highly effective SERS substrate, has been monolithically integrated inside a microfluidic chip. Individual NPGD is known to feature an order of magnitude larger surface area than its projected disk area. The increased surface area arises from nanoscale pores and ligaments three-dimensionally distributed in the NPGD, which manifest themselves as high-density SERS hot-spots. High-density NPGD arrays further guarantee large coverage of these hot-spots on the microchannel floor. The sensor performance has been demonstrated using Rhodamine 6G to quantify spatial uniformity and determine the shortest detection time. Next, the sensor is applied to detect two biomolecules, dopamine and urea, with unprecedented detection limit and speed compared to other existing microfluidic SERS sensors. The sensor holds great promise in point-of-care applications for various biomolecular detections.

Abstract. We report stamping surface-enhanced Raman spectroscopy (S-SERS) for label-free, multiplexed, molecular sensing and large-area, high-resolution molecular imaging on a flexible, nonplasmonic surface without solution-phase molecule transfer. In this technique, a polydimethylsiloxane (PDMS) thin film and nanoporous gold disk SERS substrate play the roles as molecule carrier and Raman signal enhancer, respectively. After stamping the SERS substrate onto the PDMS film, SERS measurements can be directly taken from the "sandwiched" target molecules. The performance of S-SERS is evaluated by the detection of Rhodamine 6G, urea, and its mixture with acetaminophen, in a physiologically relevant concentration range, along with the corresponding SERS spectroscopic maps. S-SERS features simple sample preparation, low cost, and high reproducibility, which could lead to SERSbased sensing and imaging for point-of-care and forensics applications.

A method is proposed to synthesize oxide nanoparticles in insulators, using metal-ion implantation and following thermal oxidation, which introduces less damage compared to the sequential implantation of metal ions and oxygen ions. Ni-oxide nanoparticles are formed in O2 gas flow at ∼800°C for 1h, through thermal oxidation of Ni metal nanoparticles, which were introduced in SiO2 by charging-free negative ion implantation of 60keV. After the oxidation, optical absorption in the visible region, which is due to Ni metal nanoparticles in the specimen, disappears, and a steep absorption edge of insulator NiO appears around ∼4eV. Simultaneously, the large magnetization of Ni metal nanoparticles changes to a weak magnetization of antiferromagnetic NiO nanoparticles. The nanoparticle formation is confirmed by transmission electron microscopy observation.

The commutation torque ripple in the six-step square-wave driving mode of the brushless DC motor affects the motor performance and generates mechanical vibrations and noise when used for industrial applications. The cause of commutation torque ripple is analysed in this study and a non-linear transient model of the phase current during the commutation interval is developed. According to the transient-current model, the commutation voltage and the time required to produce a constant torque can be calculated without current sampling; this makes the control system easier to realise in industrial applications, and reduces the need for a high performance controller. Based on the pulsewith modulated chopping method and quasi-Z-source net, the proposed control system can adjust the motor speed using a constant-voltage power supply and reduce the commutation torque ripple over the entire speed-adjustable range. A torque transducer is used to measure the dynamic torque ripple in the experiment. The results show that the proposed commutation torque-ripple reduction strategy can reduce the dynamic torque ripple by about 70% in both simulation and experiment compared with the traditional driving methods. Torque ripple in BLDCM driving systemThe torque ripple of the BLDCM is formed by three components: cogging torque, reluctance torque and mutual torque [23]. Cogging torque is a common shortcoming in PM motors, and can be minimised during motor design. PM motors with surface mounted

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Optical coherence tomography (OCT) provides signi¯cant advantages of high resolution (approaching the histopathology level) real-time imaging of tissues without use of contrast agents. Based on these advantages, the microstructural features of tumors can be visualized and detected intra-operatively: However, it is still not clinically accepted for tumor margin delineation due to poor speci¯city and accuracy. In contrast, Raman spectroscopy (RS) can obtain tissue information at the molecular level, but does not provide real-time imaging capability. Therefore, combining OCT and RS could provide synergy. To this end, we present a tissue analysis and classi¯cation method using both the slope of OCT intensity signal vs depth and the principle components from the RS spectrum as the indicators for tissue characterization. The goal of this study was to understand prediction accuracy of OCT and combined OCT/RS method for classi¯cation of optically similar tissues and organs. Our pilot experiments were performed on mouse kidneys, livers, and small intestines (SIs). The prediction accuracy with¯ve-fold cross validation of the method has been evaluated by the support vector machine (SVM) method. The results demonstrate that tissue characterization based on the OCT/RS method was superior compared to using OCT structural information alone. This combined OCT/RS method k Corresponding authors.