Design and fabrication of a multipurpose compliant nanopositioning architecture
Author(s)Panas, Robert M. (Robert Matthew)
Massachusetts Institute of Technology. Department of Mechanical Engineering.
Martin L. Culpepper IV.
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This research focused on generating the knowledge required to design and fabricate a high-speed application flexible, low average cost multipurpose compliant nanopositioner architecture with high performance integrated sensing. Customized nanopositioner designs can be created in ~~1 week, for <$1k average device cost even in batch sizes of 1-10, with sensing operating at a demonstrated 59dB full noise dynamic range over a 10khz sensor bandwidth, and performance limits of 135dB. This is a ~~25x reduction in time, ~~20x reduction in cost and potentially >30x increase in sensing dynamic range over comparable state-of-the-art compliant nanopositioners. These improvements will remove one of the main hurdles to practical non-IC nanomanufacturing, which could enable advances in a range of fields including personalized medication, computing and data storage, and energy generation/storage through the manufacture of metamaterials. Advances were made in two avenues: flexibility and affordability. The fundamental advance in flexibility is the use of a new approach to modeling the nanopositioner and sensors as combined mechanical/electronic systems. This enabled the discovery of the operational regimes and design rules needed to maximize performance, making it possible to rapidly redesign nanopositioner architecture for varying functional requirements such as range, resolution and force. The fundamental advance to increase affordability is the invention of Non-Lithographically-Based Microfabrication (NLBM), a hybrid macro-/micro-fabrication process chain that can produce MEMS with integrated sensing in a flexible manner, at small volumes and with low per-device costs. This will allow for low-cost customizable nanopositioning architectures with integrated position sensing to be created for a range of micro-/nano- manufacturing and metrology applications. A Hexflex 6DOF nanopositioner with titanium flexures and integrated siliconpiezoresistive sensing was fabricated using NLBM. This device was designed with a metal mechanical structure in order to improve its robustness for general handling and operation. Single crystalline silicon piezoresistors were patterned from bulk silicon wafers and transferred to the mechanical structure via thin-film patterning and transfer. This work demonstrates that it is now feasible to design and create a customized positioner for each nanomanufacturing/metrology application. The Hexflex architecture can be significantly varied to adjust range, resolution, force scale, stiffness, and DOF all as needed. The NLBM process was shown to enable alignment of device components on the scale of 10's of microns. 150μm piezoresistor arm widths were demonstrated, with suggestions made for how to reach the expected lower bound of 25[mu]m. Flexures of 150[mu]m and 600[mu]m were demonstrated on 4 the mechanical structure, with a lower bound of ~~50[mu]m expected for the process. Electrical traces of 800[mu]m width were used to ensure low resistance, with a lower bound of ~~100[mu]m expected for the process. The integrated piezoresistive sensing was designed to have a gage factor of about 125, but was reduced to about 70 due to lower substrate temperatures during soldering, as predicted by design theory. The sensors were measured to have a full noise dynamic range of about 59dB over a 10kHz sensor bandwidth, limited by the Schottky barrier noise. Several simple methods are suggested for boosting the performance to ~~135dB over a 10kHz sensor bandwidth, about a <1Å resolution over the 200[mu]m range of the case study device. This sensor performance is generally in excess of presently available kHz-bandwidth analog-to-digital converters.
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 227-241).
DepartmentMassachusetts Institute of Technology. Department of Mechanical Engineering.
Massachusetts Institute of Technology