Carbon nanotubes (CNTs) are one of the most widely studied and commercially attractive nanoparticles studied to date. Their commercial success is best quantified by the production volume of CNTs, which is growing exponentially, and is currently estimated at 5000 ton/yr. In part, this success can be attributed to the physical properties of CNTs, some of which are unlike any other engineering material (e.g. Young's Modulus of 1 TPa, a tensile strength of 100 GPa, thermal conductivities up to 3500 Wm-1K-1). However, these off-the-chart properties only apply to high quality individual nanotubes whereas most commercial applications require tens to millions of carbon nanoparticles to be assembled into one device. Unfortunately, the mechanical and electronic figures of merit typically drop by at least an order of magnitude in comparison to the constituent nanoparticles once integrated into an assembly. It is therefore critical to develop new manufacturing processes which enable assembling CNTs in a controlled fashion and to integrate these CNT aggregates in devices. These devices are extremely challenging to manufacture reliably, not only because of challenges in the synthesis and assembly of CNTs but also because these fragile CNT structures need to be interfaced with electrodes for electrical read-out, and often need to be in contact with gases or liquids for sensing, microfluidic, biomedical and energy storage applications. In this EPSRC Adventurous Manufacturing grant, we demonstrate a multi-scale manufacturing approach that allows to individually optimise different device length scales in an approach that has never been attempted previously. Bringing these manufacturing methods together is challenging because they rely on different alignment processes and have different thermal budgets, but when integrated correctly, phase 1 of the project demonstrated that they enable the manufacturing of radically new nanomaterial based devices. Ultimately, this new set of manufacturing techniques form a platform technology that can be used to solve a multitude of engineering problems and find applications in chemical sensors, biomedical applications, microfluidics and actuators. This project is partnering with UK based manufacturing companies to ensure that the processes developed in this project are embedded in the UK industry and become easily accessible to both academic and industrial stakeholders.

This proposal falls under the Manufacturing with light call and investigates the use of digital multimirror devices (DMDs) to perform controlled laser ablative machining, and multiphoton polymerisation for subtractive and additive laser-based manufacturing respectively. We will process a range of materials such as metals, semiconductors, paper, high value items such as gemstones, as well as polymers and biocompatible polymers. DMDs are computer-addressable arrays of reflective mirrors (typically up to one million mirrors per chip), which can have a pattern such as a letter, logo or even a full-page display imposed on the array surface. A laser pulse can then be reflected off the patterned mirror array and the image demagnified by several orders of magnitude before being directed to the workpiece intended for machining. The laser energy density at the workpiece can be high enough to cause ablative material removal or multiphoton polymerisation in the exposed regions, thereby 'printing' a minified version of whatever was displayed on the DMD. Rapid laser-based single-shot machining of complex patterns at micron (or even smaller) size scales is a novel and industrially-relevant process technology. The programme here is to extend our DMD-based machining to the manufacturing sector, in areas such as security, safety, anti-counterfeiting, MEMS and silicon photonics, biocompatible templates and more. The programme will optimise this laser-based processing technology and then apply it to the widest range of materials across the identified user spectrum. We will engage with engineers and technologists as well as laser-based manufacturing companies who have a need for rapid, low cost and flexible processing techniques.

Chemical separations are critical to almost every aspect of our daily lives, from the energy we use to the medications we take, but consume 10-15% of the total energy used in the world. It has been estimated that highly selective membranes could make these separations 10-times more energy efficient and save 100 million tonnes/year of carbon dioxide emissions and £3.5 billion in energy costs annually (US DoE). More selective separation processes are essential to "maximise the advantages for UK industry from the global shift to clean growth", and will assist the move towards "low carbon technologies and the efficient use of resources" (HM Govt Clean Growth Strategy, 2017). In the healthcare sector there is growing concern over the cost of the latest pharmaceuticals, which are often biologicals, with an unmet need for highly selective separation of product-related impurities such as active from inactive viruses (HM Govt Industrial Strategy 2017). In the water sector, the challenges lie in the removal of ions and small molecules at very low concentrations, so-called micropollutants (Cave Review, 2008). Those developing sustainable approaches to chemicals manufacture require novel separation approaches to remove small amounts of potent inhibitors during feedstock preparation. Manufacturers of high-value products would benefit from higher recovery offered by more selective membranes. In all these instances, higher selectivity separation processes will provide a step-change in productivity, a critical need for the UK economy, as highlighted in the UK Government's Industrial Strategy and by our industrial partners. SynHiSel's vision is to create the high selectivity membranes needed to enable the adoption of a novel generation of emerging high-value/high-efficiency processes. Our ambition is to change the way the global community perceives performance, with a primary focus on improved selectivity and its process benefits - while maintaining gains already made in permeance and longevity.

In this instrument development project we will be designing, constructing and testing two laser systems producing UV light pulses with sufficient energy to mark, cut or drill various non-ferrous engineering materials, be it removing small amounts precisely or in a wholesale manner that accompanies an explosion of the target material. The key advantages of the proposed systems are that they will be efficient and offer unique properties for the emitted light that cannot be found in any other laser system in the world. The first is the colour, or wavelength, of the light that will be shorter than almost all other solid-state laser systems; next and for just one of the instruments, the energy in each pulse and their frequency of arrival will be comparable to the smaller industrial-standard excimer gas lasers, which are used for many processes in the electronics manufacturing industry but rely on toxic and corrosive gases and very high voltage discharges to generate the UV light; while the second instrument will have one thousand times less energy per pulse than the first, it will deliver the same number more pulses per second, making it very useful for rapid precision micro-processing, where speed and accuracy are a premium. For us to be able to make these novel laser systems we will exploit an old technology that has re-emerged as a potential platform architecture, cryogenic cooling. Cryogenic cooling applied to high energy laser systems with high average powers has become accepted as the credible route toward laser driven fusion reactors and extreme-peak-power laser facilities (NIF - https://lasers.llnl.gov/, DiPOLE - at STFC Rutherford Appleton Laboratory (RAL) http://www.stfc.ac.uk, HiLASE - http://www.hilase.cz), clearly evidence of the potential efficiency of the approach. Employing this method we will develop a platform technology that underpins both of the systems detailed above and will enable the unique characteristics of our proposed manufacturing laser instruments. At the end of the project we will have developed a clear route for transferring the knowledge to enable the manufacturing of these lasers and begun testing their performance for materials processing in collaboration with UK laser micro-processing industrial partners.