Farid Amalou

Progress towards wafer‐scale fabrication of ultrasound arrays for real‐time high‐resolution biomedical imaging

Purpose – High‐frequency transducer arrays that can operate at frequencies above 30 MHz are needed for high‐resolution medical ultrasound imaging. The fabrication of such devices is challenging not only because of the fine‐scale piezocomposite fabrication typically required but also because of the small size of arrays and their interconnects. The purpose of this paper is to present an overview of research to develop solutions for several of the major problems in high‐frequency ultrasound array fabrication.Design/methodology/approach – Net‐shape 1‐3 piezocomposites operating above 40 MHz are developed. High‐quality surface finishing makes photolithographic patterning of the array electrodes on these fine scale piezocomposites possible, thus establishing a fabrication methodology for high‐frequency kerfless ultrasound arrays.Findings – Structured processes are developed and prototype components are made with them, demonstrating the viability of the selected fabrication approach. A 20‐element array operating...

Techniques for wirebond free interconnection of piezoelectric ultrasound arrays operating above 50 MHz

Interconnects between high frequency ultrasound (HFUS) arrays and external circuitry may be difficult and expensive because of the small element pitch, as low as 15 µm, and the large number of piezoelectric elements, up to 256. The wire bonding commonly used can be time consuming and difficult to achieve on piezocomposite material because of the relatively soft filler material. Moreover, the minimum pitch is limited by the footprint requirement for the bonding head. This requires the creation of an electrical fan-out, in turn increasing the size of the array package; this interconnect technology is disadvantageous for medical applications such as ophthalmology and dermatology. This paper proposes a wirebond free bonding process for HFUS piezocomposite arrays operating at frequencies above 30 MHz. The suggested process is integration of ultrasound “chips” with a silicon (Si) wafer using state-of-the-art fabrication techniques and materials including anisotropic conductive film, through silicon vias, powder blasting and laser machining.

Validation of a fully integrated platform and disposable microfluidic chips enabling parallel purification of genome segments for assembly

Recent progress in the field of genetic engineering has opened up the door to novel synthetic biology applications. Microfluidic technology has been emphasized as a key technology to support the development of these applications. While several important synthetic biology protocols have been developed in microfluidic format, no study has yet demonstrated on‐chip error control. In synthetic biology protocols, the purification phase is a critical error control process which enhances the reliability of the genome segment assembly by removing undesired oligos. In this context, we report the design and characterization of a fully integrated platform, demonstrating the purification of up to 4 genome segments in parallel, prior to their off‐chip assembly. The key innovation of this platform is the decoupling control strategy which eliminates the need to integrate expensive components onto the microfluidic device, enabling lower cost, disposability and rapid operation. Unlike most microfluidic chips where fluid connector plugs are needed to connect external pumps, this approach is plug‐less and the chips are simply connected to the control breadboard by clamping. Furthermore the passive chip is isolated from the active control layer thereby eliminating the risk of sample‐to‐sample contamination in the reusable parts. As a validation of this fully‐integrated system, the parallel on‐chip purification of genome segments was demonstrated with ratio of correct phenotypes after final assembly up to 20% superior to the bench controls, proving thereby the suitability of the platform for synthetic biology applications. Biotechnol. Bioeng. 2014;111: 1627–1637.

Modelling and optimisation study on the fabrication of nano‐structures using imprint forming process

Purpose – Nano‐imprint forming (NIF) is a manufacturing technology capable of achieving high resolution, low‐cost and high‐throughput fabrication of fine nano‐scale structures and patterns. The purpose of this paper is to use modelling technologies to simulate key process steps associated with the formation of patterns with sub‐micrometer dimensions and use the results to define design rules for optimal imprint forming process.Design/methodology/approach – The effect of a number of process and pattern‐related parameters on the quality of the fabricated nano‐structures is studied using non‐linear finite element analysis. The deformation process of the formable material during the mould pressing step is modelled using contact analysis with large deformations and temperature dependent hyperelastic material behaviour. Finite element analysis with contact interfaces between the mould and the formable material is utilised to study the formation of mechanical, thermal and friction stresses in the pattern.Finding...

Modelling the Nano-Imprint Forming process for the production of miniaturised 3D structures

Nano-imprint forming (NIF) as manufacturing technology is ideally placed to enable high resolution, low-cost and high-throughput fabrication of three- dimensional fine structures and the packaging of heterogeneous micro-systems (S.Y. Chou and P.R. Krauss, 1997). This paper details a thermo-mechanical modelling methodology for optimising this process for different materials used in components such as mini-fluidics and bio-chemical systems, optoelectronics, photonics and health usage monitoring systems (HUMS). This work is part of a major UK Grand Challenge project - 3D-Mintegration - which is aiming to develop modelling and design technologies for the next generation of fabrication, assembly and test processes for 3D-miniaturised systems.

Minimising the risk of defects in nano-imprint forming

Nano-imprint forming (NIF) is among the most attractive manufacturing technologies offering high yield and low-cost fabrication of three-dimensional fine structures and patterns with resolution of few nanometres. Optimising NIF process is critical for achieving high quality products and minimising the risk of commonly observed defects. Using finite element analysis, the effect of various process parameters is evaluated and design rules for safe and reliable NIF fabrication formulated. This work is part of a major UK Grand Challenge project - 3D-Mintegration - for design, simulation, fabrication, assembly and test of next generation 3D-miniaturised systems.

Microsystems technology for the separation of fetal cells from maternal blood

At present the successful diagnosis of fetal abnormalities relies on the analysis of fetal genetic material obtained through invasive procedures such as amniocentesis and chorionic villus sampling (CVS). These procedures are expensive, time consuming and have the potential to cause harm to both the fetus and mother. A review of current diagnostic techniques in the field of prenatal care is presented. State of the art developments in fetal cell separation from maternal blood are discussed. A novel device concept that uses Microelectromechanical System (MEMS) manufacturing methods and magnetic field filtration is described.