By Isha Jain, thurj Staff
In the past, the sciences were often regarded as a hierarchy. Professor Federico Capasso – from Harvard’s School of Engineering and Applied Sciences – describes society’s original outlooks: “The fields that are more theoretical, more far from reality, particularly in science and technology, by some ill-conceived argument were viewed as superior intellectually.” But for Capasso, “this mentality is a total disaster: we create the differences between these fields. Nature does not distinguish whether a phenomenon is chemistry, physics or biology…it is a completely artificial thing.” Recently, we have come to appreciate science as more of a coplanar playing field. Every subfield exists to serve its own purpose as well as to augment progress in other subfields. One of the newest embodiments of this mantra is Harvard’s very own Center for Nanoscale Systems (CNS).
The term “nano” tends to conjure up an image of the unknown, the mysterious that resides in a parallel world, see-sawing reality and science fiction. But the groundbreaking research being conducted in the CNS seeks to conquer such ambiguities in the form of applicative innovations. It is often difficult to conceptualize orders of magnitude that deviate from our day-to-day encounters. A nanometer is 10-9 of a meter. A human hair is approximately 100 microns or 100,000 times a nanometer in width. A typical covalent bond is approximately one-tenth of a nanometer. So, what truly lies behind all the hype of this esoteric nano-world? The primary motivation driving this field of study is the increased importance of minute forces we tend to disregard on larger scales. These forces drastically alter the classical laws of physics. We enter a realm of phenomena such as quantum-tunneling, carbon nanotubes and quantum dots.
The Center for Nanoscale Systems is an endeavor by the Harvard faculty to approach multidisciplinary questions through a nanoscale lens. Rather than simply considering single units at the nanoscale level, the Center strives to understand systems built from nanoscale components. In addition, CNS serves as a technological melting pot. Supported by grants from the NSF, the center offers the Harvard research community access to a myriad of technological resources for imaging, nanofabrication and materials synthesis.
Why here? Why now? What next?
When it comes to the life sciences, Harvard’s research is in many ways unparalleled. But when it comes to engineering, more technically focused institutions like MIT tend to be seen as at the forefront of scientific efforts. With such a distinctive reputation, the center faced the challenges of establishing an Engineering and Physics based institution in the midst of a largely biology-oriented community. As Professor Capasso explains, “The advantage of CNS is that you have a lot of interdisciplinary activity, because the lines between biology, chemistry and physics are being blurred at the nanoscale level. A number of professors had the wisdom to propose a service center, a facility. These fields have developed so much that you need a centralized facility. It cannot be done in the old style garden variety manner.” CNS is now at the forefront of competitive nanotech research due to the collaborative efforts of its faculty and to the top-notch technology it houses.
Projects through a Peephole
Dr. Federico Capasso exudes a love of science. With a distinctive Italian accent, he remarks: “I like to think of myself as an engineer. I work in a number of interlocked, interdisciplinary areas. I like to bridge the gap between so called fundamental stuff, basics and applications.” In one of its projects, Capasso’s group seeks to understand a newly discovered phenomenon. Contrary to what one may believe, a vacuum is a surprisingly dynamic condition. Specific materials possess intrinsic properties at the nanoscale level. In the mid 1900s, a theory known as the Casimir effect first highlighted the existence of attractive forces between macroscale objects. Now, the Capasso group has found the first evidence of repulsive forces caused by a so called “vacuum energy”. Two plates made of special materials can now be engineered to have a levitating effect. The weight of the upper weight can be countered by the repulsive force between the two plates.
The group is also pioneering development in laser technology. “Last year our group developed a tiny laser spectrometer on a chip, something like a finger nail. The Holy Grail is to go to the longest possible wavelength. At this wavelength, light can penetrate non metallic enclosures, so it could be a substitute to x-rays. It could be used in security check points to detect weapons.”
Robert Westervelt – a Professor of Physics and Applied Physics at the CNS – works to engineer circuitry using quantum dots. It was originally believed that the number of microprocessors to fit on a chip would double every three years. However, physical laws place an upper limit on this prediction. Then came the revolutionizing idea of quantum computers, based on quantum dots. Quantum dots contain a specific number of electrons (each with an up or down spin). This is analogous to the binary system currently utilized in common computers. Westervelt has led the pioneering research of connecting quantum dots, which in turn could be used to build nanoscale circuits.
In the biotech realm, the Westervelt group has constructed a “hybrid integrated circuit and microfluidic chip”. This fusion of technologies enables researchers to trap and move thousands of small droplets and living biological cells in specific configurations. This biological etch-a-sketch has been used to move yeast and mammalian cells at speeds in the tens of microns per second.
At the forefront of integrative bio-nanotechnology at the CNS is the work of Dr. Charles Lieber. There are two approaches generally used by nanotechnologists: top-down and bottom-up. The Lieber lab focuses on the bottom-up approach to design nanoscale building blocks and then eventually build complex and elaborate systems. For example, the Lieber group devises sensory technology to detect specific protein-protein interactions or the presence of bio-hazardous materials in trace amounts. The basis of this technology is the manner in which the presence of a particular molecule can be translated into an electrical signal. In another project, Lieber attempts to model engineering at the nanoscale level off the architecture of the brain. Today’s computers have to be restricted to the concept of the 2-dimensional flat chip. Dr. Lieber has been crafting the foundation for branching nanowires, to overcome this restriction.
The Future of the CNS
Capasso, Westervelt, Liebert and many other faculty at the CNS are paving the path for integrative research in the study of nanoscale systems. As Capasso asserts, “the future lies in lowering the barrier between science, engineering and technology”. The Center for Nanoscale System combines all three: studying, modifying and creating new connections between the basic particles that make up our world.