Laser Direct Write (LDW) is one of the most versatile direct-write techniques, which uniquely enable adding, removal and modifying target materials without any physical contact. Additionally, it is able to process complex materials with a resolution spanning more than three orders of magnitude, from millimetres to microns, which makes LDW process a unique technique to fabricate structures that are not possible using other techniques.

One of the unique features that the LDW technique provides is that it allows processing and modifying of a wide range of materials for fabrication of devices and structures within a research laboratory environment or even as an entire manufacturing system on the factory floor.

The key components of a LDW system normally consist of three parts: the laser source, beam delivery pathway and substrate translation system. The heart of any LDW process is always the laser source. A wide range of lasers, from ultrafast pulsed systems to continuous-wave (c.w.) systems, can be applied during the LDW process as befits different applications.

To date, many kinds of LDW systems have been used in science and engineering, and they can be classified into three main categories: LDW subtraction, where material is removed; LDW addition, where material is added; and finally LDW modification, where material is modified. The technique we have developed belongs to the last category (LDW modification), namely using the LDW procedure to modify the material in the substrate in order to form designed patterns based on light-induced photo-polymerisation.

In our work, a new approach towards the fabrication of paper-based POC diagnostic sensors is proposed, which is a simple laser-based direct-write (LDW) procedure that uses polymerisation of a photopolymer to produce the required fluidic channels in porous substrates. Furthermore, this LDW technique is also further developed and explored for introduction of a range of additional functionalities in paper-based microfluidic devices.

Over the last two and a half years we have been funded by the U.K. scientific funding body, EPSRC, via two grants to explore this work, and have filed four patents to cover various aspects of this novel laser-writing method. Furthermore, more recently, we have also received funding from our university based Network for Antimicrobial Resistance and Infection Prevention (NAMRIP) in the form of a pump-priming award to explore the use of such laser-patterned paper-platforms for anti-microbial resistance testing. We have validated the commercial usefulness of this laser-based method through a market research exercise funded by Innovate UK, and hence are in the process of starting our own spin-off company.

PhD Projects:

Laser-based fabrication of medical diagnostic devices in paper

Supervisor: Dr C L Sones
Co-supervisor: Prof R W Eason 

The broader theme of our research activity is the development of affordable, rapid and user-friendly medical diagnostic devices. This research is highly multi-disciplinary which not only draws upon expertise in laser physics/engineering and microfluidics, but also vital knowledge of biochemistry and medicine. The aim of the projects below is to develop in paper, microfluidics-based point-of-care diagnostics devices using our proprietary laser-based techniques. The strategy is to employ these innovative manufacturing methods to create custom-designed, unique microfluidic flow-patterns that when used in conjunction with adapted/modified bio-chemical assays provide additional functionalities to simple lateral-flow-type products (such rapid dipstick tests) currently in the market thus enhancing their application domains.

Project 1: The objective is the development of tests which allows the simultaneous detection of multiple biomarkers which help early-stage detection of the targeted application of tuberculosis (TB), a disease which according to the WHO Global TB Report 2015, ranks alongside HIV as a leading cause of death worldwide.,

Project 2: The focus here is the development of point-of-care diagnostics tests which allow the detection of bacterial pathogens that cause infections such as upper respiratory tract infections and urinary tract infections. These unique devices, in addition, will be designed to enable tests for the pathogens susceptibility to different antibiotics, an important pre-requisite that provides an essential guide to a GP/Consultant in prescribing the correct antibiotic required for the treatment of that specific bacterial infection.

The projects are mainly experimentally oriented, but there will be opportunities for theoretical simulations.

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