The bulk of the currently available biosensing techniques often require complex liquid handling, and thus suffer from problems associated with leakage and contamination. We demonstrate the use of an organic electrochemical transistor for detection of lactate (an essential analyte in physiological measurements of athlete performance) by integration of a room temperature ionic liquid in a gelformat, as a solid-state electrolyte.

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A smartphone application, called CAnal, was developed as a colorimetric analyzer in paper-based devices for sensitive and selective determination of mercury(II) in water samples. Measurement on the double layer of a microfluidic paper-based analytical device (μPAD) fabricated by alkyl ketene dimer (AKD)-inkjet printing technique with special design doped with unmodified silver nanoparticles (AgNPs) onto the detection zones was performed by monitoring the gray intensity in the blue channel of AgNPs, which disintegrated when exposed to mercury(II) on μPAD. Under the optimized conditions, the developed approach showed high sensitivity, low limit of detection (0.003 mg L-1 , 3SD blank/slope of the calibration curve), small sample volume uptake (two times of 2 μL), and short analysis time. The linearity range of this technique ranged from 0.01 to 10 mg L-1 (r 2 = 0.993). Furthermore, practical analysis of various water samples was also demonstrated to have acceptable performance that was in agreement with the data from cold vapor atomic absorption spectrophotometry (CV-AAS), a conventional method. The proposed technique allows for a rapid, simple (instant report of the final mercury(II) concentration in water samples via smartphone display), sensitive, selective, and on-site analysis with high sample throughput (48 samples h-1 , n = 3) of trace mercury(II) in water samples, which is suitable for end users who are unskilled in analyzing mercury(II) in water samples.

A bstractThis work presents the fabrication, characterisation and the performance of a wearable, robust, flexible and disposable chemical barcode device based on a micro-fluidic platform that incorporates ionic liquid polymer gels (ionogels). The device has been applied to the monitoring of the pH of sweat in real time during an exercise period. The device is an ideal wearable sensor for measuring the pH of sweat since it does not contents any electronic part for fluidic handle or pH detection and because it can be directly incorporated into clothing, head-or wristbands, which are in continuous contact with the skin. In addition, due to the micro-fluidic structure, fresh sweat is continuously passing through the sensing area providing the capability to perform continuous real time analysis. The approach presented here ensures immediate feedback regarding sweat composition. Sweat analysis is attractive for monitoring purposes as it can provide physiological information directly relevant to the health and performance of the wearer without the need for an invasive sampling approach.

A microfluidic chip with an integrated planar microcoil was developed for Nuclear Magnetic Resonance (NMR) spectroscopy on samples with volumes of less than a microliter. Real-time monitoring of imine formation from benzaldehyde and aniline in the microreactor chip by NMR was demonstrated. The reaction times in the chip can be set from 30 min down to ca. 2 s, the latter being the mixing time in the microfluidic chip. Design rules will be described to optimize the microreactor and detection coil in order to deal with the inherent sensitivity of NMR and to minimize magnetic field inhomogeneities and obtain sufficient spectral resolution.

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aWe report the design, fabrication, and characterization of practical optofluidic valves fabricated using laser printer lithography. Valves are opened by directing optical energy from a solid-state laser, with similar power characterisitcs to those used in CD/DVD drives, to a spot of printed toner where localized heating melts an orifice in the polymer layer in as little as 500 ms, connecting previously isolated fluidic components or compartments. Valve functionality, response time, and laser input energy dependence of orifice size are reported for cyclo-olefin copolymer (COC) and polyethylene terephthalate (PET) films. Implementation of these optofluidic valves is demonstrated on pressure-driven and centrifugal microfluidic platforms. In addition, these "one-shot" valves comprise a continuous polymer film that hermetically isolates on-chip fluid volumes within fluidic devices using low-vapor-permeability materials; we confirmed this for a period of one month. The fabrication and integration of optofluidic valves is compatible with a range of polymer microfabrication technologies and should facilitate the development of fully integrated, reconfigurable, and automated lab-on-a-chip systems, particularly when reagents must be stored on chip for extended periods, e.g. for medical diagnostic devices, lab-on-a-chip synthetic systems, or hazardous biochemical analysis platforms.

We present the fabrication, characterisation and performance of four novel ionic liquid polymer gels (ionogels) as photo-actuated valves incorporated into microfluidic manifolds. The ionogels incorporate benzospiropyran units and phosphonium based ionic liquids. Each ionogel is photo-polymerised in-situ in the channels of a poly(methyl methacrylate) micro-fluidic device, generating a manifold incorporating four different micro-valves. The valves are actuated by simply applying localised white light irradiation, meaning that no physical contact between the actuation impulse (light) and the valve structure is required. Through variation of the composition of the ionogels, each of the micro-valves can be tuned to open at different times under similar illumination conditions. Therefore, flows through the manifold can be independently controlled by a single light source. At present, the contraction process to open the channel is relatively rapid (seconds) while the recovery (expansion) process to re-close the channel is relatively slow (minutes), meaning that the valve, in its current form, is better suited for single-actuation events.