Magnetic resonance-based detection has a wide range of advantages such as exquisite chemical specificity, the capability to be applied to samples in all states of matter, and a broad range of temperatures, at the same time being a non-ionizing, nondestructive analytical technique. It suffers, however, from an inherent lack of sensitivity, which becomes even more critical when dealing with small samples, for example, sub-microliter volumes. Resorting to detectors closely conforming to the “small” samples significantly improves the signal-to-noise ratio (SNR) that is being lost by reducing the sample amount, that is, by reducing the available number of spins contributing to the total signal. The tremendous progress of microsystems technologies during the past decades has also been reflected in the way the detectors for magnetic resonance are being designed and built, making possible the advent of the field called “micronuclear magnetic resonance”. The present chapter is aiming at presenting the state of the art in the fabrication of miniaturized detectors for nuclear magnetic resonance, with a focus on the innovation that this field has been enjoying in the recent years.
Arrays of radio-frequency (RF) coils have had a great impact on magnetic resonance imaging (MRI). This chapter demonstrates the block diagram of a CMOS frequency division multiplexer (FDM) capable of merging up to eight MR channels and transmitting them over a single cable. It introduces a novel solution to overcome the size and complexity issues associated with nuclear magnetic resonance (NMR)-phased arrays. Several microfabrication techniques have been combined with the decoupling strategies to produce arrays of volume and surface coils for MR spectroscopy and imaging. Combining microfabrication with microelectronics technologies enables highly complex microarrays for magnetic resonance microscopy on a very small footprint. These technologies will give rise to novel hardware concepts in the MRI sector, for example, processing the MR signal directly at the coil interface, which will be a game changer for the whole spectrometer hardware setup.
This chapter discusses two flow-imaging techniques that are useful for measuring flow on a microscopic scale: time of flight (ToF) and phase contrast (PC). It explores the physical limitations to the resolution and applicable parameter ranges of the flow. The chapter presents some specific examples, including the characterization of liquid exchange in different aneurysm models, the measurements of velocity fields, and the determination of wall shear stress (WSS) from the measured velocity field. ToF magnetic resonance imaging (MRI) is a possible method for observing flow on a microscopic scale. The PC method is well established for non-microscopic applications and is also suitable for flow imaging on microscopic scales. The ToF technique is used to measure the liquid exchange in different aneurysm models with a resolution of < 150 µm and validated these results with computer simulations.
This chapter describes the basic principles of using magnetic resonance imaging (MRI) sequences for the specific purpose of nuclear magnetic resonance (NMR) microscopy. A major difference between NMR microscopy and small animal MR or human MR lies in the fact that in NMR microscopy, it is not sufficient to just make an image. The versatility of MR primarily lies in the richness of contrast mechanisms it allows to measure and which yield the possibility to yield unique information about the tissue under study. This is especially true for NMR microscopy, where the mere production of a structural image is - in most applications - not very relevant and can be done much better, faster, cheaper, and with higher spatial resolution with other techniques such as optical imaging or acoustic microscopy. The ability to measure water diffusion is one of the contrast mechanisms, which are quite unique for NMR.
Chapter 1 Magnets for Small-Scale and Portable NMR Bernhard Blümich, Bernhard Blümich RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Worringerweg 2, 52074 Aachen, GermanySearch for more papers by this authorChristian Rehorn, Christian Rehorn RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Worringerweg 2, 52074 Aachen, GermanySearch for more papers by this authorWasif Zia, Wasif Zia Sir Peter Mansfield Imaging Center, University of Nottingham, United KingdomSearch for more papers by this author Bernhard Blümich, Bernhard Blümich RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Worringerweg 2, 52074 Aachen, GermanySearch for more papers by this authorChristian Rehorn, Christian Rehorn RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Worringerweg 2, 52074 Aachen, GermanySearch for more papers by this authorWasif Zia, Wasif Zia Sir Peter Mansfield Imaging Center, University of Nottingham, United KingdomSearch for more papers by this author Jens Anders, Jens Anders University of Stuttgart, Institute of Smart Sensors, Pfaffenwaldring 47, Stuttgart, 70569 GermanySearch for more papers by this authorJan G. Korvink, Jan G. Korvink Karlsruhe Institute of Technology, Institute of Microstructure Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344 GermanySearch for more papers by this author Book Author(s):Jens Anders, Jens Anders University of Stuttgart, Institute of Smart Sensors, Pfaffenwaldring 47, Stuttgart, 70569 GermanySearch for more papers by this authorJan G. Korvink, Jan G. Korvink Karlsruhe Institute of Technology, Institute of Microstructure Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344 GermanySearch for more papers by this author First published: 18 May 2018 https://doi.org/10.1002/9783527697281.ch1Citations: 7Book Series:Advanced Micro and Nanosystems AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary The dominating component of most NMR instruments is the magnet, as it typically exceeds the electronics and the sample in size and weight. To shrink the complete instrument to compact size, a prime challenge rests in the miniaturization of the magnet. In this endeavor, most efforts today focus on magnets from permanently magnetic materials. This chapter summarizes the state of the art of compact, permanent NMR magnets and explores new design concepts that may guide the construction of small permanent magnets with high magnetic fields or fields sufficiently homogeneous to resolve the chemical shift in NMR spectra of liquids. Citing Literature Micro and Nano Scale NMR: Technologies and Systems RelatedInformation
To date, NMR microcoils are mostly used for enhancing the spin sensitivity in homonuclear 1D NMR experiments because the design and manufacturing of standard microcoil probes for multinuclear detection require complex and sophisticated electronic circuitry. In this chapter, an alternative approach toward microcoil NMR, which uses a simplified front-end consisting of a planar spiral microcoil-on-a-chip terminating a coaxial cable with no tuning and matching circuitry, is discussed, both experimentally and theoretically. Due to the simple nature of the front-end without tuning or matching elements, the proposed solution can operate as a high-resolution "all-in-one" NMR system, with broadband character. Moreover, this relatively simple setup is capable of executing 1D broadband as well as complex heteronuclear 2D pulse sequences, on practically any combination of nuclides and with excellent mass sensitivity. The exciting broadband properties of microcoils require a radical shift in the conceptual thinking of RF circuitry for NMR applications and probe design and, moreover, the broadband coil concept provides a low-cost alternative to commercial NMR probe systems, enabling mono- and multidimensional experiments using a single microcoil. It is therefore somewhat surprising that broadband circuit probes are not in the normal arsenal of commercially available probes, which in turn raises the question how widely applicable and robust the concept is. To answer this question, in this chapter, we will also discuss how non-tuned circuits demand a different view on the classical electronics in NMR probes and open up the window to explore (micro) technologies to make integrated small NMR systems. We will further motivate why for these systems it becomes particularly attractive to co-design the spectrometer electronics together with the broadband coils to enhance system performance and robustness. Finally, in the conclusions and outlook section, we will outline how the paradigm-shifting idea of a non-resonant system opens up new horizons for NMR spectrometers, such as the reality of magnetic field-independent NMR probes.
This chapter deals with the emerging field of integrated circuit (IC)-based and IC-assisted μNMR detectors. IC-assisted detectors are hybrid solutions consisting of an off-chip detection coil and a dedicated transceiver application-specific integrated circuit (ASIC). The chapter starts with a brief introduction into complementary metal oxide semiconductor (CMOS) and bipolar complementary metal oxide semiconductor (BiCMOS) technologies, in which the most salient features related to the design of NMR electronics and detection coils are highlighted. It shows the cross section of a generic modern CMOS technology. The chapter discusses the advantages of monolithic integrations of the transceiver electronics for NMR applications. It provides a detailed treatment of the possibilities associated with using IC technology for designing the RF receiver front-end in direct proximity of the NMR detection coil. The chapter also provides a review of the state-of-the-art in IC-based and IC-assisted μNMR systems.
The drive to improve the sensitivity of nuclear magnetic resonance (NMR) to smaller and smaller sample volumes has led to the development of a variety of techniques distinct from conventional inductive detection. In this chapter, we focus on the technique of force-detected NMR as one of the most successful in yielding sensitivity improvements. We review the rationale for the technique, its basic principles, and give a brief history of its most important results. We then cover in greater detail its application in the first demonstration of three-dimensional (3D) nuclear magnetic resonance imaging (MRI) with nanometer-scale resolution. Next we present recent developments and likely paths for improvement. Finally, the technique and its potential are discussed in the context of competing and complementary technologies.
The existence of various contact layers and interfaces between the layers will inevitably introduce both electrical and thermal contact resistances into a practical thermoelectric device. In order to minimize the performance reduction due to the contact resistances of the interfaces, preparation and characterization of thermoelectric junction/interfaces become an important prerequisite for thermoelectric module fabrication. This chapter provides a brief overview on the basic principles and the state-of-the-art technologies that are crucial to achieving low-contact resistances for the fabrication of high-performance thermoelectric devices. A simplified model is developed to describe the influence of electrical and thermal contact resistances on the performance of thermoelectric devices and provide a quantitative evaluation of the contact resistance required for satisfactory manufacturing of thermoelectric modules. The chapter further describes the technique for characterization of electrical contact resistance based on a scanning resistance probe, together with experimental results to demonstrate the usefulness and capability of the equipment.
Heat flux and temperature sensors find a significant niche in the market of modern sensors. Many existing and new applications require accurate measurement of heat fluxes. Recently, interest in the use of thermoelectric modules as heat flux sensors has grown. Thermoelectric modules are widely used for cooling (Peltier effect) or generation of energy (Peltier and Seebeck effects). In heat flux sensors the thermoelectric effect – the Seebeck effect – is also used, which is the physical basis for the differential thermocouple sensors too. As the sensors are measuring devices, their calibration is required to ensure high accuracy for applications. Calibration allows getting the coefficient of the output signal proportionality to the heat flux. This chapter discusses the main parameters of heat flux sensors and formulas that determine their dependence on physical properties and design features. It presents these parameters of the sensors together with the key factors influencing them.
The current chapter reviews the principles and methods for exploiting thermodynamically driven phase separation effects such as nucleation and growth and spinodal decomposition for enhancing the thermoelectric figure of merit through bulk nanostructuring of selected IV–VI systems. Special emphasis is laid on the p-type (GeTe)0.87(PbTe)0.13 and the n-type (Pb0.95Sn0.05Te)0.92(PbS)0.08, exhibiting very high maximal ZTs of 2.2 and 1.5, respectively.
Thermoelectric generators (TEGs) convert heat into electricity, and could contribute to the world's increasing energy demand by harvesting low-energy-density heat, such as waste heat produced during the conversion of fossil fuels to electricity or heat from solar radiation. The efficiency of the heat-electricity conversion is dictated by the material properties. This chapter presents the key material properties that help define the heat-to-electricity conversion efficiency. TEG is an electronic device that uses the Seebeck effect to convert a heat flow into an electron flow. The Seebeck coefficient is intimately related to the electronic structure and mobility of the charge carrier. Controlling the shape of the density of state at the Fermi level in a material should enable tuning its Seebeck coefficient. Hence, it is crucial to understand the electronic structure of conducting polymers. The chapter summarizes how the electrical conductivity, the Seebeck coefficient, and the thermal conductivity of conducting polymers depend on their oxidation level.
Cell manipulation requires not only the ability to observe the cells but also the ability to probe the cells. This chapter focuses on the manipulation of biological samples inside two different platforms, that is, environmental scanning electron microscope (ESEM) and microfluidic device. One example of cell manipulation inside ESEM platform is presented, that is, the manipulation of cells using dual nanoprobe, and one example of cell manipulation inside microfluidic device is highlighted, that is, the manipulation of cells using thermoresponsive polymer actuated (TPA) probe. Unlike Atomic Force Microscope (AFM) system, ESEM-nanomanipulation system can provide both 2D and 3D manipulations on the sample, thus increasing the flexibility of the measurement. Poly(N-isopropylacrylamide) (PNIPAAm) solution saves energy when generating the soluble–insoluble transition. To realize the probe manipulation, the semiclosed microchip has the bath in the middle of microchannel.
There are several considerable approaches to handle and manipulate nano-objects toward a seamless integration. However, general approaches from macroscopic handling and robotics, using different kinds of grippers and visual feedback, cannot be applied directly to the micro- and nanoscales. Instead, micro and nanohandling approaches take advantage of certain effects on the nanoscale. The apparent need of micro- and nanomanipulation can be particularly addressed by the scanning electron microscope (SEM). The SEM is originally a powerful tool for the acquisition of high-magnification images. One of the newly developed measurements is the transverse compression of single fibers with high-resolution cross-sectional imaging. This measurement is performed inside the SEM in low-vacuum mode for two reasons. First, the visualization of the fiber cross section requires high-resolution imaging and the SEM provides this necessary resolution. Second, the nonconducting sample fibers cannot be coated in order to avoid influences on the mechanical properties.
This chapter focuses on organic micromechanical resonators. It introduces four design schemes for polymeric micromechanical resonators. The schemes showcase different actuation methods and the specific fabrication techniques involved. The quality factor of polymeric micromechanical resonators is also discussed for three scenarios. In the first scenario, the resonator is immersed in a viscous environment, such as gas or a liquid. The chapter discusses the scenario of relaxed (no residual stress) and unrelaxed (with residual stress) polymeric micromechanical resonators in vacuum. Relaxed structures are, for example, beams and plates, whose mechanical behavior is dominated by their flexural rigidity. Unrelaxed structures are, for example, strings and membranes, and their mechanics is dominated by tensile stress. Finally, the chapter showcases three successful applications that make use of the particular properties of polymeric micromechanical resonators.
This chapter presents the stiffness and kinematic analysis of a novel compliant parallel micromanipulator. There are two types of the structure of the compliant mechanism: serial structure and parallel structure. Kinematics issue of parallel mechanism is related to the joint variables and position and orientation of the end-effector, which is the basis of many performance indexes. The matrix displacement method is utilized to formulate the stiffness model of the proposed novel parallel micromanipulator. An accurate kinematics model is beneficial for the performance evaluation. Moreover, it can be used for control purpose for the micromanipulator. The stiffness and kinematics models of the manipulator are derived based on the matrix displacement method. The manipulator is compact in size and large in stroke, which makes it suitable for biomedical manipulations in a limited space. The stiffness and kinematic analysis method is implemented on the proposed manipulator as an example.
As the telemetering art progresses under the impetus of both aircraft and industrial needs, the requirement for accurate transducing becomes more and more important. This article describes a null-balance type of transducer which is inherently capable of achieving an accuracy comparable to that of present-day transmission links.
Microfabrication, the technology adopted in standard semiconductor manufacturing industry such as thin film deposition, photolithography, etching, has driven micro-electro-mechanical-system (MEMS) and lab-on-a-chip toward batch fabrication, low expense, and precisely controlled geometry. MEMS microbial fuel cells (MFCs), via miniaturization of an MFC to be in micrometer scale, are useful for a small-size power supply or lab-on-a-chip devices for scientific research on exoelectrogen. Besides applications as an energy converter, MEMS MFC is useful for scientific studies, including the mechanism of extracellular electron transfer (EET) of exoelectrogen, screening the electricity generation capability of individual exoelectrogen. Miniaturized MFC-on-a-chip devices also find application in biosensors for toxic chemical detection. This chapter illustrates a two-chamber configuration MEMS MFC. The MFC includes two chambers, anode and cathode chambers, separated by an ion exchange membrane, such as PEM (proton exchange membrane).
This chapter presents high performance magnetically driven microtool (MMT) actuated by permanent magnets, which have significantly higher magnetic fields than electromagnetic coils, in a microfluidic chip for cell manipulations. High power (mN order), high precision (mm order) and high speed (over 280 mm/sec) actuation can be achieved by reducing friction on the MMT. Three different approaches to reduce friction were discussed, the driving unit development, the actuation field modification, and the MMT shape. By integrating the microfluidic technologies and robotics technologies on the MMT, high throughput physical cell control can be achieved. Several biomedical applications will be introduced including multi-channel sorting and cell stimulation.
