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Microsystems and Nanotechnology Division
The mission of the Microsystems and Nanotechnology Division is to advance nanofabrication technologies and use them to develop innovative integrated measurement microsystems. The division is organized into the following three groups: the Nanostructure Fabrication and Measurement (NFM) Group, Photonics and Optomechanics Group, and Biophysical and Biomedical Measurement (BBM) Group.
TECHNICAL QUALITY OF THE WORK
The generally impressive work of the Nanostructure Fabrication and Measurement Group is broadly focused on improving quality and efficiency in nanofabrication and measurement through emphasis on a closed-loop iteration process (virtuous cycles). Group presentations emphasized the traceability chain and the ways that a detailed understanding of nanofabrication and measurement impacts this chain. For example, the point was made that the transitioning of calibration tools to the field typically involves multiple steps, with each step introducing compounding errors. Therefore, nanoscale fabrication and measurement provide a direct way of improving commercial calibration tools by greatly reducing the uncertainty in the root calibration. Even measurement devices as simple as a tape ruler, which typically would be manufactured to have an accuracy less than 1 mm, rely upon root calibration at the nanometer scale. Of course, this precision is even more critical in quantum information, such as for the precise and accurate placement of quantum emitters within chip-based microcavities and also in medicine, where more efficient and higher-accuracy measurements are required in development, testing, and production of nanomedicines such as DOXOrubicin.
The NFM Group is working effectively with the Biophysical and Biomedical Measurement Group, and the Photonics and Optomechanics Group. The NFM Group expressed the belief that continued improvements made possible by the virtuous cycle will strongly impact nanophotonics in particular, where new application areas, such as frequency microcombs, are already demanding nanoscale control of macroscale resonant structures for dispersion engineering. This collaborative approach to solving problems is commendable.
The Photonics and Optomechanics Group interacts with other NIST groups and is rapidly expanding the range of research to address a wide variety of NIST problems, such as NOAC and miniaturized, integrated atomic clocks. The group has achieved a number of recent breakthroughs, such as integrated beams in multiple wavelengths for the next generation of Strontium magneto-optical traps for atomic optical clocks. The group demonstrated an accelerometer with an order of magnitude better sensitivity, based on combining their photonic expertise with their micro-electromechanical systems (MEMS) expertise. This is likely to have a significant impact on the inertial-navigation field, and like many of its other projects, it will have a large commercial impact. The photonics team is engaged in exciting projects, engineering devices at ever-higher frequencies and achieving record high Qs and using them for quantum measurements at room temperature. The scientific depth of the group’s scientists, the quality and control of the fabrication processes, and the exciting world-record research results that are being generated are impressive.
The science of biology has critical length scales, from nanometers to meters and beyond. Biology is also incredibly complex at every one of these scales. The Biophysical and Biomedical Measurement Group is tasked with the formidable challenge of performing triage on critical problems over this range of lengths and finding critical technologies and problems to address. One of the great challenges in biomedical measurement is moving from the culture dish to the three-dimensional (3D) physiological world of tissue, and probing with microelectronic sensors the chemical and physical state of tissue, both diseased and healthy. There is a unique effort by the Biophysical and Biomedical Measurement (BBM) Group in the Microsystems and Nanotechnology Division, in collaboration with the Advanced Electronics Group within the Nanoscale Device Characterization Division, to develop ultra-sensitive nanofabricated field-effect transistor pH sensors, which can ultimately be deployed in a clinical setting to probe the interior of tissue.
In collaboration with the electron-spin paramagnetic sensors being developed within the BBM Group, the researchers will begin to develop 3D models of the oxygen, pH, and other critical metabolites in tissue. It is very exciting that there is a collaboration developing with AstraZeneca, one of the COVID19 vaccine developers using the technologies being developed here.
Micro-nanofluidics plays a central role in biomedical technologies, including biological object sorting by size in a range from the nanoscale to the millimeter scale, and in developing fluidic connectivity between modular biological units. The team addressing fluidics and cytometry is developing new high-throughput, high-precision sorting technologies and measurement technologies to provide precise quantitative measurement of the extremely low flow rates often found in these systems. A challenge in the field of micro-nanofluidics is the complex and often unknown structure of the objects being transported and how they interact with other objects and surfaces. DNA nanotechnology offers an ability to design biological structures using well-defined rules that can create both novel materials and reproducible complex structures that can be used as transporters in biological systems and as precision standards.
The team researching microphysiological systems is bringing all of the above technologies together in a major effort to put a “body on a chip,” which consists of a number of interconnected modules that have tissue cultures of various organs (e.g., liver and bone marrow) to which various drugs and physiological stressors (e.g., oxygen, pH, and temperature) may be applied to ascertain in a longitudinal manner the way that the various tissue components interact with one another. This is a daunting challenge, and it would be beneficial to achieve more integration of the technologies discussed above in a 3D manner within this modular assembly of intercommunicating tissues. The impact of this technology would be vast, because so many drugs fail with increasing environment complexity.
TECHNICAL EXPERTISE OF THE STAFF
The staff of all groups within the division is well organized and well qualified, with impressive scientific depth and clear definitions of responsibility and good synergy across groups within the division.
ADEQUACY OF RESOURCES
The NFM Group operates in conjunction with the Gaithersburg cleanroom facility, vital to its mission that supports focus areas in electron-beam lithography, focused ion beam, scanning electron microscopy, atomic force microscopy, super-resolution optical microscopy, and biomolecular assembly. Work within NFM and the clean-room facility directly impact the Photonics and Optomechanics Group and the BBM Group. It will be important to maintain the cleanroom nanofabrication and characterization facilities at a state-of-the-art level. Continued support and investments in this facility will be broadly leveraged across technical groups. These facilities will also directly support NIST initiatives such as NOAC.
EFFECTIVENESS OF DISSEMINATION OF OUTPUTS
The NFM Group is doing an excellent job of disseminating the results of its work through publications, direct engagements with industry and universities, distribution of nanofabrication tools such as the nanolithography Toolbox, and the development of the JMONSEL simulator tool for precision calibration of nanoscale features in scanning electron microscopy. Dissemination of research results on the subject of nanoplastics, which is emerging as an environmental challenge with direct consequences for human health, will grow in importance.
The Photonics and Optomechanics Group’s publication rate in top-tier journals is excellent, and the rate of patent filings indicates the novel aspects of their research. The group seems tightly coupled with the NFM Group in particular and interacts with other NIST groups. Staff members also have collaborations with scientists outside of NIST and seem to be leveraging their skills in other groups to secure outside funding and expand the visibility and impact of their research.
GENERAL CONCLUSIONS
The programs within the Microsystems and Nanotechnology Division are of high quality and are well aligned with the NIST mission. The researchers are generally superb and frequently among the world’s best researchers in the areas of microsystems and nanotechnology, as evidenced by the citation data for their publications. The facilities and equipment are top notch, although there are some concerns about maintaining expensive processing systems at state-of-the-art levels. The dissemination of outputs is reasonable and appropriate, including publication in top-tier journals, cooperative research and development agreements (CRADAs) and other relationships with industry, and a steady flow of associates into and out of the organization, to and from academia, industry, and national and government laboratories. These interchanges occasionally yield permanent appointments at NIST.
RECOMMENDATION: The Microsystems and Nanotechnology Division should perform a forward-thinking analysis to address the concerns about maintaining expensive processing systems at state-of-the-art levels.
The division chief presented a plot that effectively made the point that the division staff is working in a strongly interdisciplinary manner within the division and with many other divisions across NIST. This indication that the activities within the division are not siloed—a concern for many technical organizations—was borne out by the reviews of the division’s groups.