This review examines the current state of the art lab-on-a-chip and microfluidic based biosensor technologies used in the detection of cardiac biomarkers. The determination and quantification of blood based, cardiac biomarkers are crucial in the triage and management of a range of cardiac related conditions, where time delay has a major impact on short and longer-term outcomes of a patient. The design and manufacturing of biomarker detection systems are multi-disciplinary in nature and require researchers to have knowledge of both life sciences and engineering for the full potential of this field to be realised. This review will therefore provide a comprehensive overview of chip based immunosensing technology as applied to cardiac biomarker detection, while discussing the potential suitability and limitations of each configuration for incorporation within a clinical diagnostics device suitable for point-of-care applications.

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We report an experimental and numerical characterization of three-dimensional acoustic streaming behavior in small droplets of volumes (1-30 μl) induced by surface acoustic wave (SAW). We provide a quantitative evidence of the existence of strong nonlinear nature of the flow inertia in this SAW-driven flow over a range of the newly defined acoustic parameter F{NA}=Fλ/(σ/R_{d})≥0.01, which is a measure of the strength of the acoustic force to surface tension, where F is the acoustic body force, λ is the SAW wavelength, σ is the surface tension, and R{d} is the droplet radius. In contrast to the widely used Stokes model of acoustic streaming, which generally ignores such a nonlinearity, we identify that the full Navier-Stokes equation must be applied to avoid errors up to 93% between the computed streaming velocities and those from experiments as in the nonlinear case. We suggest that the Stokes model is valid only for very small acoustic power of ≤1 μW (F{NA}<0.002). Furthermore, we demonstrate that the increase of F{NA} above 0.45 induces not only internal streaming, but also the deformation of droplets.

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Optical based analysis in microfluidic and lab-on-a-chip systems are currently considered the gold standard methodology for the determination of end point reactions for various chemical and biological reaction processes. Typically, assays are performed using bulky ancillary apparatus such as microscopes and complex optical excitation and detection systems. Such instrumentation negates many of the advantages offered by device miniaturisation, particularly with respect to overall portability. In this article, we present a CO 2 laser ablation technique for rapidly prototyping on-chip planar lenses, in conjunction with capillary action based autonomous microfluidics, to create a miniaturised and fully integrated optical biosensing platform. The presented self-aligned on-chip optical components offer an efficient means to direct excitation light within microfluidics and to directly couple light from a LED source. The device has been used in conjunction with a miniaturised and bespoke fluorescence detection platform to create a complete, palm sized system (%60 Â 80 Â 60 mm) capable of performing fluoro-immunoassays. The system has been applied to the detection of cardiac Troponin I, one of the gold standard biomarkers for the diagnosis of acute myocardial infarction, achieving a lower detection limit of 0.08 ng/ml, which is at the threshold of clinically applicable concentrations. The portable nature of the complete system and the biomarker detection capabilities demonstrate the potential of the devised instrumentation for use as a medical diagnostics device at the point of care. V C 2013 AIP Publishing LLC.

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This paper reports the development of a novel genotyping device specifically designed for point-of-care applications. As the results of the human genome project are applied to clinical practice there is an increasing requirement for simple to operate high-speed, potentially low-cost genotyping devices for use in the clinic. The aim of such devices is not to specifically detect a full gene sequence but to monitor the presence of specific Single Nucleotide Polymorphisms (SNPs). The instrument is designed to fulfil this specific clinical requirement. Using a FRET-based assay the instrument completes a full PCR process and then performs a melting point test to determine the exact SNPs present in the sample. Results are presented in which the instrument produces results within 18 min based upon saliva samples provided by the patient. The paper also reports successful results both with purified DNA samples and saliva-based samples which were taken from subjects after experiments deliberately aimed at confusing the instrument.

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