Design and Applications of Coordinate Measuring Machines

Coordinate measuring machines (CMMs) have been conventionally used in industry for 3-dimensional and form-error measurements of macro parts for many years. Ever since the first CMM, developed by Ferranti Co. in the late 1950s, they have been regarded as versatile measuring equipment, yet many CMMs on the market still have inherent systematic errors due to the violation of the Abbe Principle in its design. Current CMMs are only suitable for part tolerance above 10 μm. With the rapid advent of ultraprecision technology, multi-axis machining, and micro/nanotechnology over the past twenty years, new types of ultraprecision and micro/nao-CMMs are urgently needed in all aspects of society. This Special Issue accepted papers revealing novel designs and applications of CMMs, including structures, probes, miniaturization, measuring paths, accuracy enhancement, error compensation, etc. Detailed design principles in sciences, and technological applications in high-tech industries, were required for submission. Topics covered, but were not limited to, the following areas: 1. New types of CMMs, such as Abbe-free, multi-axis, cylindrical, parallel, etc. 2. New types of probes, such as touch-trigger, scanning, hybrid, non-contact, microscopic, etc. 3. New types of Micro/nano-CMMs. 4. New types of measuring path strategy, such as collision avoidance, free-form surface, aspheric surface, etc. 5. New types of error compensation strategy

Responsive nanostructures for controlled alteration of interfacial properties

Responsive materials are a class of materials that are capable of “intelligently” changing properties upon exposure to a stimulus. Silk ionomers are introduced as a promising candidate of biopolymers that combine the robust, biocompatible properties of silk fibroin with the responsive properties of poly-l-lysine (PL) and poly-l-glutamic acid (PG). These polypeptides can be assembled using the well-known technique of layer-by-layer processing, allowing for the creation of finely tuned nanoscale multilayers coatings, but their properties remain largely unexplored in the literature. Thus, this research explores the properties of silk ionomer multilayers assembled in different geometries, ranging from planar films to three-dimensional microcapsules with the goal of created responsive systems. These silk ionomers are composed of a silk fibroin backbone with a variable degree of grafting with PG (for anionic species) or PL or PL-block- polyethylene glycol (PEG) (for cationic species). Initially, this research is focused on fundamental properties of the silk ionomer multilayer assemblies, such as stiffness, adhesion, and shearing properties. Elastic modulus of the materials is considered to be one of the most important mechanical parameters, but measurements of stiffness for nanoscale films can be challenging. Thus, we studied the applicability of various contact mechanics models to describe the relationship between force distance curves obtained by atomic force microscopy and the stiffness of various polymeric materials. Beyond considerations of tip size, we also examine the critical regions at which various commonly used indenter geometries are valid. Following this, we employed standard AFM probes and colloidal probes coated with covalently bonded silk ionomers to examine the friction and adhesion between silk ionomers layers. This technique allowed us to compare the interactions between silk ionomers of different chemical composition by using multilayer films containing standard silk ionomers or silk ionomers grafted with polyethylene glycol PEG. This led to the unexpected result that the PEG grafted silk ionomers experienced a higher degree of adhesion and a larger friction coefficient compared to the standard silk ionomers. Next, we move to microscale responsive systems based on silk ionomer multilayers. The first of these studies looks at the effect of assembly pH and chemical composition on the ultimate properties of hollow, spherical microcapsules. This study shows that all compositions and processing conditions yield microcapsules that show a substantial change in elastic modulus, swelling, and permeability, with maximum changes in property values (from acidic pH to basic pH) of around a factor of 6, 1.5, and 5, respectively. In addition, it was discovered that the use of acidic pH assembly inverts the permeability response (i.e. causes a drastic reduction in permeability at higher pH), whilst the use of PEG largely damps any observable trend in permeability, without adversely affecting the swelling or elastic modulus responses. In the second part of these studies, we constructed tri-component photopatterned arrays for the purpose of creating self-rolling films. This study demonstrated that the ultimate geometry of the final rolled shape can be tuned by controlling the thickness of various components, due to the creation of a stress mismatch at high pH conditions. Additionally, it was revealed that pH-driven, semi-reversible delamination of silk ionomers from polystyrene exhibited a change in both magnitude and wavelength with the addition of methanol treated silk fibroin as a top layer. Finally, we showcase examples of biologically compatible systems that incorporate non-polymeric materials in order to generate tunable optical behavior. In one study, we fabricated composite nanocellulose-silk fibroin meshes that contained genetically engineered bacteria that acted as chemically sensitive elements with a fluorescent response. The addition of silk fibroin was found to drastically improve the mechanical properties of the cellulose composite structures, safely contain the bacteria to prevent efflux into the medium, and protect the cells from moderate ultraviolet radiation exposure. The final study concludes with the creation of a self-assembled segmented gold-nickel nanorod array used as a responsive element when anchored into a hydrogen-bonded polymer multilayer. Because of the mild tethering conditions and the magnetic nickel component, the nanorods were able to tilt in response to an external magnetic field. This, in turn, allowed for the creation of a never before reported magnetic-plasmonic system capable of continuously-shifting multiple surface polariton scattering peaks (up to 100 nm shifts) with nearly complete reversibility and rapid (<1 s) response times. Overall, this research develops the understanding of the fundamental properties of several different species of silk ionomers and related polymeric materials. This understanding is then utilized to fabricate pH-responsive systems with drastic changes in modulus, permeability, and geometry. In the end, the research prototypes two types of systems with optical responses and chemical/magnetic stimuli, using materials that are chemically (i.e. silk fibroin-based) or structurally (i.e. multilayers) translatable to future work on silk ionomers. These projects all serve the purpose of advancing the understanding of materials and assembly strategies that will allow for the next generation of bioinspired responsive materials.Ph.D

Manufacturing Metrology

Metrology is the science of measurement, which can be divided into three overlapping activities: (1) the definition of units of measurement, (2) the realization of units of measurement, and (3) the traceability of measurement units. Manufacturing metrology originally implicates the measurement of components and inputs for a manufacturing process to assure they are within specification requirements. It can also be extended to indicate the performance measurement of manufacturing equipment. This Special Issue covers papers revealing novel measurement methodologies and instrumentations for manufacturing metrology from the conventional industry to the frontier of the advanced hi-tech industry. Twenty-five papers are included in this Special Issue. These published papers can be categorized into four main groups, as follows: Length measurement: covering new designs, from micro/nanogap measurement with laser triangulation sensors and laser interferometers to very-long-distance, newly developed mode-locked femtosecond lasers. Surface profile and form measurements: covering technologies with new confocal sensors and imagine sensors: in situ and on-machine measurements. Angle measurements: these include a new 2D precision level design, a review of angle measurement with mode-locked femtosecond lasers, and multi-axis machine tool squareness measurement. Other laboratory systems: these include a water cooling temperature control system and a computer-aided inspection framework for CMM performance evaluation

Development of a high-speed high-precision micro-groove cutting process

A high-speed, high-precision chip formation-based micro-groove cutting process has been developed for cutting grooves in metals with nearly arbitrarily shaped cross-sections, which have widths and depths of a few hundred nanometers to a few microns, and lengths of tens of millimeters. A flexible tool, consisting of a single-point cutting geometry mounted on the end of a small cantilever, is moved along a workpiece surface while a constant cantilever deflection is maintained to apply a cutting load. Depth of cut for a given tool shape is determined by cutting load and workpiece material properties. A major advantage of the flexible tool concept is increased depth of cut precision. Furthermore, the use of a flexible tool enables the process to be robust against machine tool registration error, guide misalignment, and component inertial deflections. The process was implemented by fitting a 5-axis micro-scale machine tool with a specially constructed micro-groove cutting assembly. Early, experiments using diamond-coated AFM probes as tools demonstrated process viability up to cutting speeds of 25 mm/min and chip formation at the sub-micron scale. However, AFM probe geometries proved too fragile for this demanding application. High quality tools with improved cutting geometries were designed and fabricated via focused ion beam machining of single-crystal diamond tool blanks, and tool edge radii of 50 - 64 nm were achieved. The improved tools enabled well-formed rectangular grooves to be cut in aluminum at up to 400 mm/min with widths of 300 nm to 1.05 microns and depths up to 2 microns. Complex compound v-shaped grooves were also produced. Virtually no tool wear (less than 20 nm) was observed over a cutting distance of 122.4 mm. Small amounts of side burr formation occurred during steady-state cutting, and exit burr formation occurred when a tool exited from a workpiece. Parallel 1.05 micron wide grooves were controllably cut as close as 1.0 micron apart, and machining of intersecting grooves was successfully demonstrated. To better understand process mechanics including chip formation, side burr formation, and exit burr formation at the small size scale involved, a 3D finite element model of the process was developed. Validation with experimental results showed that on average the model predicted side burr height to within 2.8%, chip curl to within 4.1%, and chip thickness to within 25.4%. An important finding is that side burr formation is primarily caused ahead of a tool by expansion of material compressed after starting to flow around a tool rather than becoming part of a chip. Also, three exit burrs, two on the sides of a groove and one on the bottom of a groove, are formed when a thin membrane of material forms ahead of a tool and then ruptures as the tool exits a workpiece. Finally, conclusions about the process are drawn and recommendations for future work are presented

Combining Focused Ion Beam Patterning and Atomic Layer Deposition for Nanofabrication

For nanofabrication of silicon based structures, focused ion beam (FIB) milling is a top-down approach mainly used for prototyping sub-micron devices, while atomic layer deposition (ALD) is a bottom-up approach for depositing functional thin films with excellent conformality and a nanometer level accuracy in controlling film thicknesses. Combining the strengths of FIB milling with ALD provides new opportunities for making 3D nanostructures. In FIB milled silicon, the gallium implanted surface suffers from segregation and roughening upon heating, which makes the thermal stability of the as-milled substrate a concern for the following ALD processes which are typically performed at temperatures of 150 ℃ and higher. This study aimed to explore methods for improving the thermal stability of FIB milled silicon structures for the following ALD processes. The other aim was to fabricate nanostructures by alternately using FIB milling and ALD approaches on silicon and oxide thin film materials. The experiments were started on the reduction of gallium implantation during FIB milling of silicon substrates using different incident angles. Oblique incidence of the ion beam was found an effective method for improving the thermal stability of the FIB milled silicon surfaces by decreasing their gallium content. The improved thermal stability allowed to apply ALD Al2O3 on the FIB milled surfaces to make nanotrenches. Wet etching in KOH/H2O2 was found as a second method for improving the thermal stability by removing the gallium implanted silicon layer. ALD Al2O3 thin films can be applied as milling masks to limit amorphization of silicon upon FIB milling. With the aid of KOH/H2O2 etching, nanopore arrays, nanotrenches and nanochannels were fabricated. ALD grown Al2O3/Ta2O5/Al2O3 multilayers were FIB milled and wet etched to form both 2D and 3D hard masks. The fabricated 2D masks were used for making metal structures which are applicable for electrical connections. Thin film resistors were also fabricated using this 2D mask system. In conclusion, this study illustrates that combining FIB patterning and ALD is feasible for 3D nanofabrication when the stability of FIB milled surfaces is considered and improved.Fokusoidut ionisuihkut (Focused Ion Beam, FIB) soveltuvat erilaisten materiaalien muokkaukseen mikro- ja nanomittakaavassa. FIB-työstöä on käytetty paljon piille valmistetun mikroelektroniikan materiaalien tutkimuksessa ja prototyyppien valmistuksessa. Atomikerroskasvatus (Atomic Layer Deposition, ALD) on ohutkalvojen valmistusmenetelmä, jossa kasvavan kalvon paksuus voidaan kontrolloida alle atomikerroksen tarkkuudella. ALD on nykyään erittäin tärkeä mikroelektroniikan valmistusmenetelmä. Etenkin hyvin ohuiden oksidieristeiden, kuten Al2O3:n, valmistuksessa se on nykyään lähes ainoa tapa luotettavasti peittää mikropiirien monimutkaiset nanomittakaavan rakenteet. FIB- ja ALD-menetelmien yhdistämisellä voidaan saavuttaa hyvin runsas kirjo erilaisia nanorakenteita. FIB-työstössä materiaaliin implantoituva gallium voi kuitenkin aiheuttaa ongelmia, kuten erkautumista ja pinnan karkeutumista, kun työstetty materiaali kuumennetaan ALD-kasvatuksissa 150 ℃ tai korkeampaan lämpötilaan. Tässä työssä on tutkittu erilaisia tapoja FIB-työstetyn piin termisen stabiilisuuden parantamiseksi, jotta rakenteet olisivat helpommin käytettävissä ALD-kalvojen kasvatusalustoina. Lisäksi valmistettiin useita eri tyyppisiä rakenteita tutkittuja menetelmiä yhdistämällä. Tutkimuksessa havaittiin, että ionisuihkun tulokulmaa muuttamalla pystyttiin vaikuttamaan voimakkaasti implantoituvan galliumin määrään, mikä selvästi paransi valmistettujen rakenteiden lämmönkestävyyttä. Näin valmistettuja railoja pystytään pinnoittamaan hallitusti, ja niitä voidaan kaventaa ALD-pinnoitteiden avulla erittäin tarkasti. Kemiallisessa etsauksessa pintoja muokataan hitaalla hallitulla syövytyksellä. Etsausvaiheita käytettiin sekä FIB-työstettyjen pintojen puhdistamiseen että rakenteiden valmistuksessa. Työssä kehitettiin KOH:H2O2 etsantti galliumilla kontaminoituneen piikerroksen poistamiseksi, jolloin pinta soveltui paremmin ALD-kasvatuksiin käytetystä ionien tulokulmasta riippumatta. Nanomittakaavassa implantoitujen alueiden poistoa voitiin myös käyttää nanorakenteiden valmistukseen. Kasvattamalla ALD-kalvoja ennen ionisuihkulla kuviointia piin kontaminoituminen ja vaurioituminen voidaan estää täydellisesti. ALD-pinnoitteet soveltuvat hyvin myös kuvioitavaksi maskikerrokseksi. Kolmikerroksinen Al2O3/Ta2O5/Al2O3 –maskipinnoite toimii hyvin kaksiulotteisten johdekuvioiden valmistuksessa, ja ALD:n täydellisen pinnanpeittokyvyn ja FIB-työstön tarkan asemoinnin ansiosta voidaan tehdä myös kolmiulotteisia maskeja pinnalla olevien rakenteiden päälle. Näin voidaan kuvioida rakenteita esimerkiksi yksittäisen mikropartikkelin tai nanokuidun pinnalle. Työ osoitti, että FIB- ja ALD-menetelmät ovat hyvin yhdistettävissä. Yhdessä kemiallisen etsauksen kanssa voidaan valmistaa hyvin runsaasti erilaisia 2D- ja 3D- rakenteita – käytännössä lähinnä mielikuvitus on rajana

Developing new optical imaging techniques for single particle and molecule tracking in live cells

Differential interference contrast (DIC) microscopy is a far-field as well as wide-field optical imaging technique. Since it is non-invasive and requires no sample staining, DIC microscopy is suitable for tracking the motion of target molecules in live cells without interfering their functions. In addition, high numerical aperture objectives and condensers can be used in DIC microscopy. The depth of focus of DIC is shallow, which gives DIC much better optical sectioning ability than those of phase contrast and dark field microscopies. In this work, DIC was utilized to study dynamic biological processes including endocytosis and intracellular transport in live cells. The suitability of DIC microscopy for single particle tracking in live cells was first demonstrated by using DIC to monitor the entire endocytosis process of one mesoporous silica nanoparticle (MSN) into a live mammalian cell. By taking advantage of the optical sectioning ability of DIC, we recorded the depth profile of the MSN during the endocytosis process. The shape change around the nanoparticle due to the formation of a vesicle was also captured. DIC microscopy was further modified that the sample can be illuminated and imaged at two wavelengths simultaneously. By using the new technique, noble metal nanoparticles with different shapes and sizes were selectively imaged. Among all the examined metal nanoparticles, gold nanoparticles in rod shapes were found to be especially useful. Due to their anisotropic optical properties, gold nanorods showed as diffraction-limited spots with disproportionate bright and dark parts that are strongly dependent on their orientation in the 3D space. Gold nanorods were developed as orientation nanoprobes and were successfully used to report the self-rotation of gliding microtubules on kinesin coated substrates. Gold nanorods were further used to study the rotational motions of cargoes during the endocytosis and intracellular transport processes in live mammalian cells. New rotational information was obtained: (1) during endocytosis, cargoes lost their rotation freedom at the late stage of internalization; (2) cargoes performed train-like motion when they were transported along the microtubule network by motor proteins inside live cells; (3) During the pause stage of fast axonal transport, cargoes were still bound to the microtubule tracks by motor proteins. Total internal reflection fluorescence microscopy (TIRFM) is another non-invasive and far-field optical imaging technique. Because of its near-field illumination mechanism, TIRFM has better axial resolution than epi-fluorescence microscopy and confocal microscopy. In this work, an auto-calibrated, prism type, angle-scanning TIRFM instrument was built. The incident angle can range from subcritical angles to nearly 90y, with an angle interval less than 0.2y. The angle precision of the new instrument was demonstrated through the finding of the surface plasmon resonance (SPR) angle of metal film coated glass slide. The new instrument improved significantly the precision in determining the axial position. As a result, the best obtained axial resolution was ~ 8 nm, which is better than current existing instruments similar in function. The instrument was further modified to function as a pseudo TIRF microscope. The illumination depth can be controlled by changing the incident angle of the excitation laser beam or adjusting the horizontal position of the illumination laser spot on the prism top surface. With the new technique, i.e., variable-illumination-depth pseudo TIRF microscopy, the whole cell body from bottom to top was scanned

A NEW METHOD OF WAVELENGTH SCANNING INTERFEROMETRY FOR INSPECTING SURFACES WITH MULTI-SIDE HIGH-SLOPED FACETS

With the development of modern advanced manufacturing technologies, the requirements for ultra-precision structured surfaces are increasing rapidly for both high value-added products and scientific research. Examples of the components encompassing the structures include brightness enhancement film (BEF), optical gratings and so forth. Besides, specially designed structured surfaces, namely metamaterials can lead to specified desirable coherence, angular or spatial characteristics that the natural materials do not possess. This promising field attracts a large amount of funding and investments. However, owing to a lack of effective means of inspecting the structured surfaces, the manufacturing process is heavily reliant on the experience of fabrication operators adopting an expensive trial-and-error approach, resulting in high scrap rates up to 50-70% of the manufactured items. Therefore, overcoming this challenge becomes increasingly valuable. The thesis proposes a novel methodology to tackle this challenge by setting up an apparatus encompassing multiple measurement probes to attain the dataset for each facet of the structured surface and then blending the acquired datasets together, based on the relative location of the probes, which is achieved via the system calibration. The method relies on wavelength scanning interferometry (WSI), which can achieve areal measurement with axial resolutions approaching the nanometre without the requirement for the mechanical scanning of either the sample or optics, unlike comparable techniques such as coherence scanning interferometry (CSI). This lack of mechanical scanning opens up the possibility of using a multi-probe optics system to provide simultaneous measurement with multi adjacent fields of view. The thesis presents a proof-of-principle demonstration of a dual-probe wavelength scanning interferometry (DPWSI) system capable of measuring near-right-angle V-groove structures in a single measurement acquisition. The optical system comprises dual probes, with orthogonal measurement planes. For a given probe, a range of V-groove angles is measurable, limited by the acceptance angle of the objective lenses employed. This range can be expanded further by designing equivalent probe heads with varying angular separation. More complicated structured surfaces can be inspected by increasing the number of probes. The fringe analysis algorithms for WSI are discussed in detail, some improvements are proposed, and experimental validation is conducted. The scheme for calibrating the DPSWI system and obtaining the relative location between the probes to achieve the whole topography is implemented and presented in full. The appraisal of the DPWSI system is also carried out using a multi-step diamond-turned specimen and a sawtooth brightness enhancement film (BEF). The results showed that the proposed method could achieve the inspection of the near-right-angle V-groove structures with submicrometre scale vertical resolution and micrometre level lateral resolution