Search

This paper presents the design and simulation of piezoelectric micro pump integrated with micro needle. The proposed micro pump adopted rectangular piezoelectric vibrator supplied with an external alternating current voltage. It has four primary components: electrodes, piezoelectric plate, PDMS (polydimethylsiloxane) membrane and channel with inlet and outlet bottom up and whole setup is constructed on a glass base. The simulations are carried out by subjecting the developed model to voltage changes, material changes which shows the satisfactory results. The micro pump possesses a flow rate of 4.1 ml/min at an input voltage 10 V with frequency 300 Hz while it is integrated with Micro Needle is having 4.67 ml/min. High pumping rates at low applied voltages making the proposed model significantly important for Transdermal controlled drug delivery applications.

During the 2000's and 2010's Raman spectroscopy has proved its potential to be used for chemical fingerprinting of biological materials. This has enabled this technique to be translated as a novel diagnostic tool for disease diagnosis with high sensitivity and specificity. Raman scattering, being a weak process, relies greatly on the power and spectral quality of the excitation source for its effectiveness. Advent of relatively high power, frequency stabilized semiconductor lasers which has relatively small form factor when compared to its gas laser counterparts enabled developing portable Raman systems for clinical diagnostics.

We report the development of a fiber-based Raman sensor to be used in tumour margin identification during endoluminal robotic surgery. Although this is a generic platform, the sensor we describe was adapted for the ARAKNES (Array of Robots Augmenting the KiNematics of Endoluminal Surgery) robotic platform. On such a platform, the Raman sensor is intended to identify ambiguous tissue margins during robot-assisted surgeries. To maintain sterility of the probe during surgical intervention, a disposable sleeve was specially designed. A straightforward user-compatible interface was implemented where a supervised multivariate classification algorithm was used to classify different tissue types based on specific Raman fingerprints so that it could be used without prior knowledge of spectroscopic data analysis. The protocol avoids inter-patient variability in data and the sensor system is not restricted for use in the classification of a particular tissue type. Representative tissue classification assessments were performed using this system on excised tissue.

We demonstrate a microfluidics-based fluorescence detection device where the filters, source, detector, and electronically controlled valves are embedded into a Polydimethylsiloxane (PDMS)-based microfluidic chip. The device reported here has been specifically designed for chlorophyll a fluorescence sensing in autonomous systems, such as oceanic applications. In contrast to a monolithic approach, the modular approach made the fabrication of this device simpler and cheaper. For fluorescence detection, an InGaN/GaN LED is used as the excitation source to specifically excite chlorophyll a; a metal-dielectric Fabry–Perot filter was used to extinguish out-of-band excitation. A simple Si photodiode is used as detector and provided with a thermally evaporated CdS emission filter to block the excitation source. This filter combination provides an excellent solution to the difficult problem of combining high-rejection excitation and emission filters in an integrated thin-film format. Furthermore, the metal-dielectric filter provides a much broader angular response than a comparable multilayer Bragg mirror, which is a key advantage in the integrated format. We use a novel paraffin wax-based valve design affords low power single-use actuation, between 0.5 and 1 J per actuation and withstands 0.6 bar differential pressure, which provides better performance than its previously reported counterparts. The remote valve-controlled operation of the fluorescence detection system is demonstrated, illustrating the measurement of a chlorophyll a solution, with a detection limit of 340 μM and subsequent valve-controlled flushing of the measurement reservoir.

We report the results of a comparative study of Fourier domain analysis (FDA) and texture analysis (TA) of optical coherence tomography (OCT) images of resected human breast tissues for binary classification between normal–abnormal classes and benign–malignant classes. With the incorporation of Fisher linear discriminant analysis (FLDA) in TA for feature extraction, the TA-based algorithm provided improved diagnostic performance as compared to the FDA-based algorithm in discriminating OCT images corresponding to breast tissues with three different pathologies. The specificity and sensitivity values obtained for normal–abnormal classification were both 100%, whereas they were 90% and 85%, respectively for benign–malignant classification.

We report a chemometric prediction of the toxicity and quality of liquor using an optofluidic sensor based upon Waveguide Confined Raman Spectroscopy (WCRS). The WCRS sensor was used to record the Raman spectra, each obtained from a 20 µl sample of a given alcoholic beverage with and acquisition time of 20 s. This was used to predict, simultaneously, both the methanol concentration (toxicity) and ethanol concentration (quality), with an accuracy of 0.1% and 0.7% by volume, respectively, using a Partial Least Squares-based chemometric model. The model sensor is shown to be capable of identifying toxic liquors, based on the test performed on different types of liquor samples. Copyright © 2013 John Wiley & Sons, Ltd.

P.G.B. acknowledges financial support from the Engineering and Physical Sciences Research Council (including the SUPERGEN programme). S.A.F. acknowledges financial support from the Austrian Federal Ministry of Economy, Family and Youth and the Austrian National Foundation for Research, Technology and Development as well as the Austrian Science Fund (FWF): P26870-N19. K.D. thanks the UK EPSRC for funding and the European Union project FAMOS (FP7 ICT, contract no. 317744). When lithium–oxygen batteries discharge, ​O2 is reduced at the cathode to form solid ​Li2O2. Understanding the fundamental mechanism of ​O2 reduction in aprotic solvents is therefore essential to realizing their technological potential. Two different models have been proposed for ​Li2O2 formation, involving either solution or electrode surface routes. Here, we describe a single unified mechanism, which, unlike previous models, can explain ​O2 reduction across the whole range of solvents and for which the two previous models are limiting cases. We observe that the solvent influences ​O2 reduction through its effect on the solubility of LiO2, or, more precisely, the free energy of the reaction LiO2* ⇌ Li(sol)+ + O2−(sol) + ion pairs + higher aggregates (clusters). The unified mechanism shows that low-donor-number solvents are likely to lead to premature cell death, and that the future direction of research for lithium–oxygen batteries should focus on the search for new, stable, high-donor-number electrolytes, because they can support higher capacities and can better sustain discharge. Postprint

The collection and rearing of krill specimens was funded by Australian Antarctic Division science programme Project 4037 (Experimental Krill Biology: Response of krill to environmental change), and Project 4050 (Assessing change in krill distribution and abundance in Eastern Antarctica). MJC is funded by Australian Research Council grant FS110200057. The OCT imaging was funded in part by the U.K. Engineering and Physical Sciences Research Council grant EP/G061688/1, the European Union European Union project FAMOS (FP7 ICT, contract no. 317744) and the CR-UK/EPSRC/MRC/DoH (England) imaging programme. DH was funded by a School of Physics and Astronomy Student Staff Council Vacation Award research studentship. Many small open ocean animals, such as Antarctic krill, are an important part of marine ecosystems. To discover what will happen to animals such as krill in a changing ocean, experiments are run in aquaria where conditions can be controlled to simulate water characteristics predicted to occur in the future. The response of individual animals to changing water conditions can be hard to observe, and with current observation techniques it is very difficult to follow the progress of an individual animal through its life. Optical coherence tomography (OCT) is an optical imaging technique that allows images at high resolution to be obtained from depths up to a few millimeters inside biological specimens. It is compatible with in vivo imaging and can be used repeatedly on the same specimens. In this work, we show how OCT may be applied to post mortem krill samples and how important physiological data such as shell thickness and estimates of organ volume can be obtained. Using OCT we find an average value for the thickness of krill exoskeleton to be (30±4) µm along a 1 cm length of the animal body. We also show that the technique may be used to provide detailed imagery of the internal structure of a pleopod joint and provide an estimate for the heart volume of (0.73±0.03) mm3. Publisher PDF

The authors thank the UK EPSRC the CR-UK/EPSRC/MRC/DoH (England) imaging Program and the European Union project FAMOS (FP7 ICT, contract no. 317744) for funding, K.D. is a Royal Society-Wolfson Merit Award Holder. Leucocytes in the blood of mammals form a powerful protective system against a wide range of dangerous pathogens. There are several types of immune cells that has specific role in the whole immune system. The number and type of immune cells alter in the disease state and identifying the type of immune cell provides information about a person's state of health. There are several immune cell subsets that are essentially morphologically identical and require external labeling to enable discrimination. Here we demonstrate the feasibility of using Wavelength Modulated Raman Spectroscopy (WMRS) with suitable machine learning algorithms as a label-free method to distinguish between different closely lying immune cell subset. Principal Component Analysis (PCA) was performed on WMRS data from single cells, obtained using confocal Raman microscopy for feature reduction, followed by Support Vector Machine (SVM) for binary discrimination of various cell subset, which yielded an accuracy >85%. The method was successful in discriminating between untouched and unfixed purified populations of CD4+CD3+ and CD8+CD3+ T lymphocyte subsets, and CD56+CD3- natural killer cells with a high degree of specificity. It was also proved sensitive enough to identify unique Raman signatures that allow clear discrimination between dendritic cell subsets, comprising CD303+CD45+ plasmacytoid and CD1c+CD141+ myeloid dendritic cells. The results of this study clearly show that WMRS is highly sensitive and can distinguish between cell types that are morphologically identical. Publisher PDF

We thank the UK EPSRC for funding, the CR-UK/EPSRC/MRC/DoH (England) imaging programme, the European Union project FAMOS (FP7 ICT, contract no. 317744) and the European Union project IIIOS (FP7/2007-2013, contract no. 238802). We thank Tayside Tissue Bank for providing us with the tissue samples under request number TR000289. K.D. is a Royal Society-Wolfson Merit Award Holder. Optical spectroscopy and imaging methods have proved to have potential to discriminate between normal and abnormal tissue types through minimally invasive procedures. Raman spectroscopy and Optical Coherence Tomography (OCT) provides chemical and morphological information of tissues respectively, which are complementary to each other. When used individually they might not be able to obtain high enough sensitivity and specificity that is clinically relevant. In this study we combined Raman spectroscopy information with information obtained from OCT to enhance the sensitivity and specificity in discriminating between Colonic Adenocarcinoma from Normal Colon. OCT being an imaging technique, the information from this technique is conventionally analyzed qualitatively. To combine with Raman spectroscopy information, it was essential to quantify the morphological information obtained from OCT. Texture analysis was used to extract information from OCT images, which in-turn was combined with the information obtained from Raman spectroscopy. The sensitivity and specificity of the classifier was estimated using leave one out cross validation (LOOCV) method where support vector machine (SVM) was used for binary classification of the tissues. The sensitivity obtained using Raman spectroscopy and OCT individually was 89% and 78% respectively and the specificity was 77% and 74% respectively. Combining the information derived using the two techniques increased both sensitivity and specificity to 94% demonstrating that combining complementary optical information enhances diagnostic accuracy. These results demonstrate that a multimodal approach using Raman-OCT would be able to enhance the diagnostic accuracy for identifying normal and cancerous tissue types. Publisher PDF

We report the development of a fiber-based Raman sensor to be used in tumour margin identification during endoluminal robotic surgery. Although this is a generic platform, the sensor we describe was adapted for the ARAKNES (Array of Robots Augmenting the KiNematics of Endoluminal Surgery) robotic platform. On such a platform, the Raman sensor is intended to identify ambiguous tissue margins during robot-assisted surgeries. To maintain sterility of the probe during surgical intervention, a disposable sleeve was specially designed. A straightforward user-compatible interface was implemented where a supervised multivariate classification algorithm was used to classify different tissue types based on specific Raman fingerprints so that it could be used without prior knowledge of spectroscopic data analysis. The protocol avoids inter-patient variability in data and the sensor system is not restricted for use in the classification of a particular tissue type. Representative tissue classification assessments were performed using this system on excised tissue.

In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demon- strate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (∼30 s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1.JBO.17.7.077006)

Raman microspectroscopy is a label-free and nondestructive technique to measure the intrinsic chemical profile of single cells. The naturally weak Raman signals hampered the application of Raman spectroscopy for high-throughput measurements. Nearly all photosynthetic microorganisms contain carotenoids that are active molecules for resonance Raman at a 532 nm excitation wavelength. Hence, the acquisition time for a single photosynthetic microorganism can be as short as 1 ms. The carotenoid bands in Raman spectra of photosynthetic microorganisms utilizing (13)CO(2) shifted when compared to the spectra of cells utilizing (12)CO(2). Here, a mixture of (12)C- and (13)C-cyanobacterial cells were counted using a microfluidic-device-based Raman-activated cell counting procedure to prove the concept that Raman spectroscopy can be used as a high-throughput method to profile a cell population.

The detection and analysis of bio-chemical analytes are important in the fields of personal healthcare, drug development, and environmental science, among others. The field of microfluidics aims to realize portable devices which can perform fast and sensitive bioanalyte detection with minimal sample preparation. Raman spectroscopy is a powerful tool for analyte detection owing to its high specificity and its ability for multi-component detection in an analyte. Combining microfluidics with Raman spectroscopy would help achieve miniaturized analytical devices that may provide rich information about a given analyte. However, the low cross-section of Raman process demands special geometries to achieve such a convergence. The majority of the previous embodiments were restricted to free-space geometry, limiting portability. However, in recent studies, fiber-based Raman detection system incorporated in microfluidics offers the opportunity to develop portable optofluidic bioanalyte detection devices. Here, we review various approaches used for using Raman spectroscopy in microfluidics for analyte detection, and various analytical approaches that could be used to enhance the detection sensitivity of Raman spectroscopy-based detection. This is followed by a detailed discussion about the fiber-based optofluidic Raman detection systems.

Fluorescence suppression using modulated wavelength Raman spectroscopy has been investigated using a fiber Raman probe and micro-Raman spectroscopy. This may lead to enhanced differentiation between normal and cancerous tissues and cells.

A fiber Raman probe based sensor is designed to be integrated into a surgical robot. The chemical information obtained from this sensor would assist tissue margin detection and surgical guidance during laparoscopic surgical procedures.

We describe the exciting advances of using optical trapping in the field of analytical biotechnology. This technique has opened up opportunities to manipulate biological particles at the single cell or even at subcellular levels which has allowed an insight into the physical and chemical mechanisms of many biological processes. The ability of this technique to manipulate microparticles and measure pico-Newton forces has found several applications such as understanding the dynamics of biological macromolecules, cell-cell interactions and the micro-rheology of both cells and fluids. Furthermore we may probe and analyse the biological world when combining trapping with analytical techniques such as Raman spectroscopy and imaging.

In this paper, we explore the propagation of light through disordered material and ask whether we can create an optimal focus in such a scenario. We use the complex modulation of the input light (i.e. modulation in both phase and amplitude) for these studies, implemented by use a spatial light modulator (SLM) and show trapping and manipulation through a static turbid medium. We then extend the system to create a tandem SLM system with an acousto-optic deflector. This has further advantages as we can now not only project light fields into turbid media but can also create interference-free mode superpositions of light fields such as Laguerre-Gaussian (LG) and Bessel modes. This is illustrated by controlled rotation of trapped particles in weighted, interference-free superpositions of LG beams of opposite order but equal magnitude.

In this paper, we utilize the incoherent superposition of nonzero order light modes. We show that this approach brings an additional degree of freedom to the generation of optical fields and notably the formation of superpositions that are otherwise unattainable through the use of refractive or diffractive optical elements and coherent or incoherent light sources. We employ this technique in two exemplary cases: first to create a field with tunable orbital angular momentum whose spatial intensity distribution remains unchanged and second to form an unusual type of "nondiffracting" light beam. Publisher PDF

We report the first implementation of the fiber based microfluidic Raman spectroscopic detection scheme, which can be scaled down to micrometre dimensions, allowing it to be combined with other microfluidic functional devices. This novel Raman spectroscopic detection scheme, which we termed as Waveguide Confined Raman Spectroscopy (WCRS), is achieved through embedding fibers on-chip in a geometry that confines the Raman excitation and collection region which ensures maximum Raman signal collection. This results in a microfluidic chip with completely alignment-free Raman spectroscopic detection scheme, which does not give any background from the substrate of the chip. These features allow a WCRS based microfluidic chip to be fabricated in polydimethylsiloxane (PDMS) which is a relatively cheap material but has inherent Raman signatures in fingerprint region. The effects of length, collection angle, and fiber core size on the collection efficiency and fluorescence background of WCRS were investigated. The ability of the device to predict the concentration was studied using urea as a model analyte. A major advantage of WCRS is its scalability that allows it to be combined with many existing microfluidic functional devices. The applicability of WCRS is demonstrated through two microfluidic applications: reaction monitoring in a microreactor and detection of analyte in a microdroplet based microfluidic system. The WCRS approach may lead to wider use of Raman spectroscopy based detection in microfluidics, and the development of portable, alignment-free microfluidic devices.

(35 Word Limit) Applications of Waveguide Confined Raman Spectroscopy (WCRS) which realizes an alignment-free microfluidic chip for Raman spectroscopic detection of analytes is described. Separately passive optical sorting techniques in optofluidics are discussed.

We report a simple, inexpensive fabrication method to fabricate polymer microlens at the apex of optical fiber. When compared to other established protocols for fabricating microlensed fiber, this procedure allows simple and inexpensive microlensed fiber fabrication with high reproducibility. Also it is possible to tune the focal length and working distance of the fabricated lens in a wider range by controlling the curing parameters such as curing power, beam shape of the curing beam and curing time. The novel curing procedure, where a specially structured curing laser beam of wavelength 405nm was used for curing, is the key factor for this extended flexibility. Once cured, the UV curable adhesive used for fabricating these lenses had a very good transmission in visible and near-IR region, making it ideal for communication and biophotonics applications. This fabrication technique can be used in a variety of applications owing to its ability to achieve customized microlenses for specific applications.

Waveguide confined Raman spectroscopy (WCRS) incorporates a fibre based Raman detection system in a microfluidic platform enabling the spectroscopic detection of analyte. It offers the possibility to develop portable, alignment free devices for bio-analyte sensing with minimal sample preparation. Ultimate sensitivity is limited by the fibre auto-fluorescence background. Here we report enhanced bio-analyte detection sensitivity by combining WCRS with continuous wavelength modulation technique. We used urea as a model analyte and the modulation parameters have been optimized to maximize the sensitivity of the device. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical transfection is a promising technique for the delivery of foreign genetic material into cells by transiently changing the permeability of the cell membrane. Of the different optical light sources that have been used, femtosecond laser based transfection has been one of the most effective methods for optical transfection which is generally implemented using a free space bulk optical setup. In conventional optical transfection methods the foreign genetic material to be transfected is homogenously mixed in the medium. Here we report the first realization of an integrated optical transfection system which can achieve transfection along with localized drug delivery by combining a microlens fiber based optical transfection system with a micro-capillary based microfluidic system. A fiber based illumination system is also incorporated in the system in order to achieve visual identification of the cell boundaries during transfection. A novel fabrication method is devised to obtain easy and inexpensive fabrication of microlensed fibers, which can be used for femtosecond optical transfection. This fabrication method offers the flexibility to fabricate a microlens which can focus ultra-short laser pulses at a near infrared wavelength to a small focal spot (~3 µm) whilst keeping a relatively large working distance (~20 µm). The transfection efficiency of the integrated system with localized plasmid DNA delivery, is approximately 50%, and is therefore comparable to that of a standard free space transfection system. Also the use of integrated system for localized gene delivery resulted in a reduction of the required amount of DNA for transfection. The miniaturized, integrated design opens a range of exciting experimental possibilities, including the dosing of tissue slices, targeted drug delivery, and targeted gene therapy in vivo.

Optical chromatography is a powerful technique, capable of separating micron-sized particles within a fluid flow, based on their intrinsic properties, including size, shape and refractive index. Briefly, particles in a fluid flow are subject to two forces, the Stokes drag force due to the fluid and then an introduced optical force as supplied by a laser beam, acting in opposite but collinear directions. According to the particle's intrinsic hydrodynamic and optical properties, equilibrium positions may form where the two forces balance, which is highly dependent on the properties of the particle and as a result provides a means for spatial separation in a sample mixture. Optical chromatography is a passive sorting technique, where pre-tagging of the particles of interest is not required, allowing for non-discrete distributions to be evaluated and/or separated. Firstly we review the current stage of optical chromatography. We present a new advance in optical chromatography potentially enabling the unique beam delivery properties of photonic crystal fiber (PCF) to be employed and integrated into microfluidic chips. Also, for the first time a finite element method is applied to the optical field in the theoretical analysis of optical chromatography, which is found to be in excellent agreement with the current ray optics model, even for particles much smaller than the optical wavelength. This will pave the way for the technique to be extended into the nanoparticle regime.

The education system of developing countries like India lack infrastructure for teaching science through demonstrations and experiments. The teaching of optics is generally based on factual data given in text books. Students are forced to believe natural phenomena without actually getting convinced themselves through observations. This imparts a big flaw in the way students understand and experience science. The International School of Photonics SPIE (International Society for Optical Engineering) Student chapter, in Cochin University of Science and Technology (CUSAT) in India comes up with their outreach activities, which is mainly aimed at giving hands on experience for school students with Optics. The pedagogy is completely in tune with the syllabus of Indian schools. This activity is being conducted by the students who are studying Photonics in University level. This gives the students a teaching experience as well. The outreach activity has been designed in two modes – Optics Fair & Optics to School.Optics Fair is a massive outreach program which has being conducted yearly since 2006. The two day event attracts more than 1500 school students as well as general public every year. The event is divided into three sections;-Primary, Secondary & Higher Secondary and the experiments are carefully chosen that the students will be able to appreciate them with their prior knowledge in optics. The basic idea put forward is “See and Believe”. In three years this event has become very popular attracting more and more students each year.Optics to School is another mode of the outreach activity where the volunteers go to schools for a one day session where optics experiments are demonstrated to students in interesting and exciting way. The idea is to reach students in the schools in rural areas who are not able to take part in the Optics Fair due to economic constraints for transportation. This activity also has been running for past 3 years successfully.The response received for these outreach activities is overwhelming. Program is successful in its mission to invoke curiosity and interest in students towards optics. Also within the given time constraint the program is able to give an insight of subject to students.

In India, the pedagogy of science education is “believe what text book says”. Providing schools with appropriate teaching materials to enhance teaching has always been a challenge in a developing country like India. Generally it is not possible for a normal school in India to afford the expensive teaching materials to teach through demonstrations and experiments. Thus students are forced to believe what text book says rather than learning concepts through experiments. The International School of Photonics SPIE (International Society for Optical Engineering) student chapter came up with ‘Optics kit’ to supplement the teaching of optics in school level. ‘Optics kit’, developed with indigenously procured components, could be sold at an affordable prize for an average Indian School. The chapter is currently selling the kit for less than $20. The content of the kit is at par with many kits already available commercially in developed countries, and the price is just 10% compared to those kits. The kit is aimed to higher secondary level students in India, where students are taught Ray optics and basics of Wave Optics. The content of the kit is developed based on this syllabus. The Optics Kit contains simple optical elements like lens, grating, polarizer, mirror, diode laser etc. The kit can be used to demonstrate optics phenomena like interference, diffraction, polarization etc. The kit was developed based on the feedback gathered by the chapter through its outreach activities. The syllabus for the kit was developed through thorough discussion with educational experts in the field of Physics. The student community welcomed the optics kit with overwhelming enthusiasm and hence the project proved to be successful in giving an opportunity for students to “See and Believe” what they are learning.

Wavelength modulated Raman spectroscopy has recently been shown to suppress the fluorescence background generated by the sample and the substrate. Here we apply this technique to collect wavelength modulated Raman spectra from 697 individual cells for a model system of circulating tumour cells that consists of leukocytes from patient's blood, acute myeloid leukaemia cells (OCI-AML3), and breast tumour cells BT-20 and MCF-7. We study the classification behaviour of wavelength modulated Raman spectra in comparison to a common background correction method in chemometrics. Classifications using a support vector machine with a radial based kernel function were compared for classical Raman spectra, average Raman spectra of each cell and wavelength modulated Raman spectra. The dataset was divided into 80% training spectra and 20% independent validation spectra. The stability of the classification was tested by performing training and validation 200 times with randomly selected datasets. The results are displayed in box whisker plots. Cell identification based on wavelength modulated Raman spectra gives similar classification rates than classical and averaged Raman spectra with a tendency of reduced accuracies and increased modelling variations. Possible explanations and strategies to further improve the wavelength modulated Raman spectroscopy are discussed.

Standardization and quality monitoring of alcoholic beverages is an important issue in the liquor production industry. Various spectroscopic techniques have proved useful for tackling this problem. An ideal sensing device for alcoholic beverages should be able to detect the quality of alcohol with a small amount of sample at a low acquisition time using a portable and easy to use device. We propose the use of near infra-red spectroscopy on an optofluidic chip for quality monitoring of single malt Scotch whisky. This is chip upon which we have previously realized waveguide confined Raman spectroscopy. Analysis on this alignment-free, portable chip may be performed in only 2 seconds with a sample volume of only 20 µl. Using a partial least square (PLS) calibration, we demonstrate that the alcohol content in the beverage may be predicted to within a 1% prediction error. Principal component analysis (PCA) was employed for successful classification of whiskies based upon their age, type and cask. The prospect of implementing an optofluidic analogue of a conventional fiber based spectroscopic probe allows a rapid analysis of alcoholic beverages with dramatically reduced sample volumes.

In this paper we discuss optical aberrations within a multiplexed optical trapping system. We analyze two of the most powerful methods for optical trap multiplexing: time-shared beam steering and holographic beam shaping in a tandem system with an acousto-optic deflector and spatial light modulator. We show how to isolate and correct for the aberrations introduced by these individual optical components using the spatial light modulator and demonstrate the enhancement this provides to optical trapping.

We report a novel fiber probe based Raman detection system on a microfluidic platform where a split Raman probe is directly embedded into a polydimethylsiloxane (PDMS) chip. In contrast to previous Raman detection schemes in microfluidics, probe based detection offers reduced background and portability. Compared to conventional backscattering probe designs, the split fiber probe we used in this system, results in a reduced size and offers flexibility to modify the collection geometry to minimize the background generated by the fibers. Also our microfluidic chip design enables us to obtain an alignment free system. As a proof of concept we demonstrate the sensitivity of the device for urea detection at relevant human physiological levels with a low acquisition time. The development of this system on a microfluidic platform means portable, lab on a chip devices for biological analyte detection and environmental sensing using Raman spectroscopy are now within reach.

We describe the realization of integrated optical chromatography, in conjunction with on-chip fluorescence excitation, in a monolithically fabricated poly-dimethylsiloxane (PDMS) microfluidic chip. The unique endlessly-single-mode guiding property of the Photonic Crystal Fiber (PCF) facilitates simultaneous on-chip delivery of beams to perform optical sorting in conjunction with fluorescence excitation. We use soft lithography to define the chip and insert the specially capped PCF into it through a predefined fiber channel that is intrinsically aligned with the sorting channel. We compare the performance of the system to a standard ray optics model and use the system to demonstrate both size-driven and refractive index-driven separations of colloids. Finally we demonstrate a new technique of enhanced optofluidic separation of biological particles, by sorting of human kidney embryonic cells (HEK-293), internally tagged with fluorescing microspheres through phagocytocis, from those without microspheres and the separation purity is monitored using fluorescence imaging.