Making Patterns

These days, the sound of drilling at the University of Canterbury is usually associated with the huge amount of construction going on after the earthquakes, but sitting in Maan Alkaisi’s office on the fifth floor of the Electrical and Computer Engineering building, the drilling outside his office signifies something far more auspicious. “So you’re witnessing the sign with my name being changed. I got promoted to full professor,” he says. Alkaisi arrived in New Zealand in 1995 without a job, having left Iraq for Algeria and then Jordan four years earlier because of the Gulf War. Soon after arrival in Christchurch he had an interview at the University of Canterbury and was working again. “I started from zero, from a fixed term lecturer position to now achieve the position of full professor,” says Alkaisi. “It’s really pleasing when your hard work is recognised in the end.” Richard Blaikie was at the University at that time, and Alkaisi says, “I remember he took me to the lab and we had a mask aligner that was 30 years old, and a hot plate. These were the facilities, and somehow he convinced me that we could do nanotechnology. And we did it!” In the space of two years, Alkaisi and his team demonstrated that contrary to previous theories, the diffraction limit of UV light did not limit the size of structures of 100 nanometres or less. Using evanescent near field optical lithography (ENFOL), and a mask containing pattern information that was in intimate contact with the imaging layer, he was able to print patterns at 70 nanometres using UV light which has a wavelength of 465 nanometres. The paper was published in Applied Physics Letters in 1999 and has more than 170 citations. “I think it was that paper that really put us on the map,” he says. After developing the technologies to make nanoscale structures, Alkaisi started applying them. “I did my PhD back in the late 1970s on solar cells, and kept that interest,” he says. The team started to fabricate solar cells using surface texturing to reduce reflections over the entire visible range by creating nanoscale pyramids which act as light trapping elements. “In addition to the nanopyramids, we’ve also started to incorporate nanoparticles, to improve their efficiency even more,” says Alkaisi of collaborative work with Richard Tilley from Victoria University and Vladimir Golovko from the University of Canterbury. Both are investigators with The MacDiarmid Institute. The next step is to extend silicon technology to glass, and a PhD student, Amalraj Peter Amalathas started in December 2013 to apply patterning, texturing and film thickness to develop solar cells in smart windows. “I’m really very excited about this because all buildings have a lot of glass, whether it’s a house or a hundred-storey building,” says Alkaisi. “So the glass has a dual functionality, it’s a building material that you use anyway, but by coating it with some photovoltaic devices or thin films, it will also produce electricity.” Another stream of research for Alkaisi is using nanoscale and microscale patterns to understand how biological cells behave and interact. With a multidisciplinary team, including John Evans from the  University of Otago, Christchurch, he developed “bioimprint” technology (a soft lithography technique for replicating biological cells). High resolution images of cell membranes are captured and then printed onto different materials, like polystyrene, plastic permanox, glass and polymer called PDMS. Cells are then cultured on these bioimprints, to see how they behave and then compared with cells grown on flat surfaces, or cells grown on lithographically defined patterns, like microscale or nanoscale gratings, pillars, and holes. “Different cells like different patterns,” says Alkaisi. “They have their own personality.” Alkaisi has another Postdoctoral researcher, Isha Mutreja, trying to understand why cells behave differently on different substrates by looking at their surface chemistry, and what makes cells adhere and grow on the imprinted pattern as opposed to flat substrates. “As an engineer, I look at the physical and mechanical aspects and the topography to see if these have any influence. When engineers work with doctors, and biologists, and chemists, we all think differently, outside of the square and from completely different angles,” says Alkaisi. The research has implications for understanding the role that physical and mechanical forces have on cell growth, and in particular cancer cells. It may also lead to better bone implants. “When we grow a cell on these replicas, the cell sees a pattern that looks like themselves. That might improve the communication between cells and substrates, and might make the material not only biocompatible, but possibly bioactive.” Another possibility is that 3D printing could allow nanoscale features and structures of the bioimprint to be incorporated into 3D scaffolds. “That would be really very interesting,” says Alkaisi. All of Alkaisi’s work rests on making patterns and then utilising them. “Lithography is a key tool for almost all electronic and optoelectronic devices,” he says. “It is the technology we use to define the structures, so any limitations in the lithography will be reflected on what kind of devices and structures we can make.” As a founding member of The MacDiarmid Institute, Alkaisi says the formation in 2002 of The MacDiarmid Institute was a “huge relief” as it enabled the purchase of an electron beam lithography machine which allowed features to be written as small as 12 nanometres. Other purchases included a state of the art mask aligner, and an RFDC magnetron spattering system.various helpful technologies that have been integral to their continued research. “The MacDiarmid Institute is not only about equipment, although that is a huge help. It’s the network of people, it’s the contact, it’s the collaboration. It’s the fact I can ring someone like Richard Tilley and ask him for some materials, or ask him to measure something for me,” says Alkaisi. “I realised when I got to New Zealand, that it’s a small country, the resources are limited, and the only way to really get anywhere is to collaborate, instead of competing,” he says. “The MacDiarmid Institute has offered that collaborative environment, sharing of expertise, sharing of facilities. It has really helped a lot, I am grateful for what happened, and I’m sure it’s helping many others too.”