Badr Omrane

Large-Area Low-Cost Flexible Plastic Nanohole Arrays for Integrated Bio-Chemical Sensing

Detection of plasmonic resonance peak shifts of nano-structured metamaterials is a promising method for sensing bio-chemical binding events. Although the concept is widely demonstrated in the laboratory environment using surface nano-structures machined at low-throughput and high-costs, practical solutions for high-volume production of an integrated sensing device are very limited. We present a concept of an integrated architecture that combines a thin layer of plasmonic nanohole sensing arrays, organic light-emitting diode illumination source, and microfluidic chip, for point-of-care, field, or lab applications. We discuss the fabrication of the sensor components. In particular, we present the improved fabrication of master nano-structure replication stamps, and demonstrate outstanding results for producing singular sheets or scale up to roll-to-roll embossing of nanohole arrays on a 2000 ft production roll. We further demonstrate that nanohole arrays embossed on flexible polyethylene terephthalate plastic sheets, when coated with 100 nm thin Au metal film, are capable of generating average plasmonic resonance shifts of 180 nm refractive index unit. Hence, we report the extraordinary transmission and plasmonic resonance shifts of nanohole arrays fabricated on roll-to-roll plastic sheets for the very first time. Our results show that the embossed nano-structures on plastic are suitable as sensor elements in our proposed integrated sensor architecture, and a promising technology for low-cost disposable applications.

Subwavelength-resolution microwave tomography using wire grid models and enhanced regularization techniques

This paper presents a new approach to handle the nonlinear microwave tomography equations for dielectric materials. The electromagnetic tomography equations are rewritten in the framework of an equivalent wire grid model loaded with resistors and capacitors to represent the permittivity and conductivity of the material. The validation of the model is performed using near-field measurements at a frequency of 2.45 GHz on devices under test made of dielectric plates of various shapes surrounded by an unbounded free-space medium. The reconstruction algorithm is based on the contrast source inversion (CSI) technique. Here, we introduce an enhanced version of the CSI cost function by adding extra regularization terms; in addition, minimization is carried out using a logarithmic barrier constraint in order to avoid nonphysical permittivity and conductivity values. The distributions of those physical properties retrieved with experimental data, for nonhomogeneous dielectric structures of known composition, are in good agreement with the expected ones. The imaging resolution is limited by the density of the wire grid meshing.

Tungsten Lamps as an Affordable Light Source for Testing of Photovoltaic Cells

An improved Tungsten light source system for photovoltaic cell testing made from low-cost, commercially available materials is presented as an alternative to standard expensive testing equipment. In this work, spectral correction of the Tungsten light source is achieved by increasing the color temperature to ∼5200 K using inexpensive commercially available filters. Spectral measurements of the enhanced light source reveal that a better spectrum match towards the solar spectrum is achieved than what has been previously demonstrated. Specifically, the improved solar spectrum match is achieved by substantial filtering of the infrared range. The proposed setup is used to evaluate the performance of both silicon and organic based photovoltaic cells.

An Improved Light Source Using Filtered Tungsten Lamps as an Affordable Solar Simulator for Testing of Photovoltaic Cells

An improved Tungsten light source system for photo voltaic cell testing constructed from low-cost, commercially available materials is presented as an alternative to current high-cost solar simulators. In this work, spectral correction of the Tungsten light source is achieved by increasing the colour temperature to ~5200 K using inexpensive commercially available filters. Spectral measurements of the corrected light source reveal that a better spectrum match towards the solar spectrum is achieved than what has been previously demonstrated by our team. Specifically, the improved solar spectrum match is achieved by substantial filtering of the infrared range. The proposed setup is used to evaluate the performance of both silicon and organic based solar cells.

Method of fabricating a convenient light source and its evaluation in PV cell laboratory testing

This paper presents a simple method of fabricating a controlled light source for photovoltaic cell testing using commercially available materials, as a

Optimized organic photovoltaics with surface plasmons

In this work, a new approach for optimizing organic photovoltaics using nanostructure arrays exhibiting surface plasmons is presented. Periodic nanohole arrays were fabricated on gold- and silver-coated flexible substrates, and were thereafter used as light transmitting anodes for solar cells. Transmission measurements on the plasmonic thin film made of gold and silver revealed enhanced transmission at specific wavelengths matching those of the photoactive polymer layer. Compared to the indium tin oxide-based photovoltaic cells, the plasmonic solar cells showed overall improvements in efficiency up to 4.8-fold for gold and 5.1-fold for the silver, respectively.

Towards Self-Powering Touch/Flex-Sensitive OLED Systems

In this work, we present a novel design for an organic light-emitting system integrated with a mechanical energy harvesting and energy storage polymer films (patent pending). The system is configured into multiple stacked layers to form a thin, flexible, and lightweight assembly. The thin “film-like” device can be deformed and flexed to generate energy up to 0.5 mW within 100 s with ease. This platform technology finds applications in energy harvesting displays, electronic papers, key-input-pads, novel packaging, smart-IDs, disposable lab-on-a-chip optomicrofluidic systems, and much more. Results on the energy storage characteristics of the ionic polymer-metal composite film, the performance of a polyfluorene-based organic light-emitting device, and the mechanical energy transduction of the piezoelectric polymer energy harvester are presented. The polymeric nature of this platform system further makes it suitable for roll-to-roll print manufacturing, supporting applications requiring high volume and low cost.

Platform for all-polymer-based pulse-oximetry sensor

The high risk of fatal infections via inappropriately disinfected medical equipment in operative scenarios are progressively prompting for better sterilization procedures in reusable equipment. The cost for thoroughly decontaminating skin-contact medical equipment such as finger-tip pulse oximeters after each use can cost hospitals several dollars per use per device; however, disposable pulse oximeter sensors at appropriately low cost can significantly alleviate healthcare expenses while virtually eliminating the risk of infections. A polymer-based pulse oximeter sensor unit that can replace traditional reusable finger-tip sensors is proposed. The unit consists of an organic photosensor module co-fabricated with an organic light-emitting-diode module under a single process on a polymer substrate. The platform is lightweight, flexible, robust, and potentially recyclable. The design considerations, architecture, and preliminary device performance results are presented. The all-polymer nature of the system promises opportunity to manufacture disposable pulse oximeter sensors at favorably low costs to replace traditional sensor clips.

Towards self-powering touch-sensitive OLED systems

In this paper, we present a novel design of an OLED system that is integrated with a mechanical energy harvesting polymer film and energy storage polymer film (patent pending). The system is configured in multiple stacked layers to form a thin, flexible, and light-weight assembly, for applications in energy harvesting displays, electronic papers, touch-input-pads, novel packaging, and much more. Initial results on the energy storage characteristics of the polymer film, the performance of a polyfluorene based OLED, and discussions on the mechanical energy transduction are presented.

Data encoding using periodic nanostructures

Successful trials have been made through a designed algorithm to quantize, compress and optically encode unsigned 8 bit integer values in the form of images using nano optical features. The periodicity of the nano scale features (nano gratings) have been designed and investigated both theoretically and experimentally to create distinct states of variation (three on state and one off state). The benefits of using a 4 state unit information carrier is been investigated through transmission models of non ergodic and ergodic signals. A thorough investigation has targeted the effects of the use of multi-varied state nano optical features on data storage density and consequent data transmission rates.