Stephen Macken

HDR imaging evaluation of a NT-proBNP test with a mobile phone.

The determination of NT-proBNP levels is key for the monitoring of patients with diagnosed heart failure and it is a routine measurement typically performed at health care centers, which would benefit from decentralized alternatives. Here we investigate the quantitative evaluation of a well-established NT-proBNP test using a standard mobile phone (Nokia 6720) as measuring platform rather than a dedicated instrument. A Java ME software developed for this application controls the illumination and imaging of the proBNP test under defined time intervals, which enables the composition of multi-exposure sets that are processed as high dynamic range (HDR) images for contrast enhancement. The results show that HDR processing significantly increases the sensitivity and resolution of the technique achieving a performance within the diagnostics range. These results demonstrate the feasibility to exploit a ubiquitous device to decentralize the evaluation of a routine test and identify key processing alternatives to bring the performance of such systems within the diagnostics range.

Imaging fingerprinting of excitation emission matrices.

The spectral fingerprinting of the excitation emission matrix (EEM) of fluorescent substances is demonstrated using polychromatic light sources and tri-chromatic image detectors. A model of the measured fingerprints explaining their features and classification performance, based on the polychromatic excitation of the indicators is proposed. Substantial amount of spectral information is retained in the fingerprints as corroborated by multivariate analysis and experimental conditions that favor such situation are identified. In average, for five different substances, the model shows a fitting goodness measured by the Pearsons r coefficient and the root mean square deviation of 0.8541 and 0.0247 respectively, while principal component classification patterns satisfactorily compare with the EEM spectroscopy classification and respectively explain 96% and 93% of the information in the fist two principal components. The measurements can be performed using regular computer screens as illumination and web cameras as detectors, which constitute ubiquitous and affordable platforms compatible with distributed evaluations, in contrast to regular instrumentation for EEM measurements.

Towards integrated devices for computer screen photo-assisted multi-parameter sensing

The computer screen photo-assisted technique (CSPT) utilizes consumer electronic devices such as computer screens and web cameras for distributed chemical sensing. Key to this method is the development of small and disposable sensing assays able to aid the CSPT optical detection, and the evaluation of multiple indicators. Here we demonstrate CSPT identification of fluorescent indicators from individual 100 microm SU-8 (10) pillars covering an area of 4 mm x 4 mm with a density of 47 elements mm(-2). The extraction of distinctive spectral fingerprints is aided by the exploitation of a three-band Moiré interference that enables the partial Bayer decoding of the CSPT images.

Optical properties of microstructures for computer screen photoassisted experiments

SU-8 microstructured devices aiding the fluorescence detection in computer screen photoassisted experiments are demonstrated. The structures exploit computer screens as controlled light sources and ...

Monolithic SU-8 microcavities for efficient fluorescence collection

The fabrication of capped microstructures such as channels or cavities typically involves multiple production steps. In this work, we demonstrate a fabrication procedure that enables the generation of capped monolithic microstructures of arbitrary geometry in one single SU-8 exposure step. The presented method also enables the embedment of metal self-aligned surfaces for use as electrodes or mirrors. The devices furthermore demonstrate a capability of increasing fluorescent collection, as measured by an epi-fluorescent inverted microscope, by up to 15-fold.

Colour moiré interferometry for physical sensing using a standard web camera

Digital moire patterns are an effect seen in digital pictures when a high-contrast periodic object being imaged interferes with the periodic image detector in the camera. This is often an undesired ...

Microstructured Devices for Computer Screen Photo Assisted Optical Fingerprinting of High Density Response Patterns

The computer screen photo-assisted technique (CSPT) exploit computer screens as a controlled light source and web cameras as imaging detectors. When used in combination with a disposable microstructured substrate, we demonstrate the fluorescent fingerprinting of 100 mum elements packed at 46 elements/mm . The microstructures aid the fluorescent detection by breaking the substrate confinement of the fluorescence indicators emission while separating the emitted signal from the excitation. Due to this efficient separation of light it is possible for the web camera, in zoom mode, to separate individual 100 mum structures compatible with high density response pattern generation, using a standard CSPT configuration.