Sensor technologies and microsensor issues for mechatronics systems

Intelligence and flexibility are essential in a mechatronic product. To achieve the primary function of an integrated system, it is essential that the functional interaction and spatial integration between mechanical, electronic, control, and information technologies be accomplished in a synergistic way. Sensors are as important in the mechatronic system as the senses are to the human being. While the subject of sensors and the need of sensors are certainly important, it is also both pervasive and diffuse. This paper cannot in any sense be exhaustive of such a wide range of discussion, and will only attempt to discuss sensors related to mechatronics. In this paper, the role of sensors in the field of mechatronics has been identified, followed by the characterization of different sensing technologies. The discussion of microsensor technologies, advantage of microsensors, and problems with microsensors together with multisensor fusion applications is presented. An example of a capacitive micro proximity sensor using micromachining technology developed by the Center of Robotics and Intelligent Machines at North Carolina State University is also described.     

Microsensor clusters

The ready availability of MicroElectroMechanical Systems (MEMS) sensors and other microsensors makes it possible to use modern manufacturing technologies to produce affordable and highly functional groupings (clusters) of the small and capable sensors. They beneficially share computational, communication and power resources. Printed circuit boards a few centimeters on a side, populated with the sensors and other components by fast pick-and-place machines, can form the backbone of clusters for many applications. Uses include, but are not limited to: small weather stations; systems for analysis of the atmosphere and water; monitors of fluid and power distribution systems, machinery operation and the status of buildings, facilities and highway systems; and robots for a variety of applications, notably solar system exploration. The calibration of microsensors and the reliability of such sensors and clusters containing them, are issues that require additional research. Microsensor clusters offer near term benefits that will not soon be supplanted by the ‘systems on a chip’ currently under development.     

Engineering Materials for Electrochemical Sweat Sensing

Human sweat contains vast physiological information, which has been a promising resource for on-body and real-time health monitoring. Wearable sweat sensors have recently attracted an ever-increasing interest due to their promising capabilities for continuously tracking changes in health status. However, the commercialization of sweat sensors is seriously hindered by drawbacks of materials including high manufacturing and consumables costs, complex integration technology, as well as limited electrochemical signal transduction. In this review, sweat sensing principles are elaborately interpreted, and the latest advances in functional materials for biomarkers sensing in sweat are systematically summarized. Subsequently, the complex structure–activity relationships between various functional materials and sensing capabilities are further elucidated by coupling chemical structures, geometrics, electrochemical properties, and approaches for materials manufacturing. Furthermore, the integration of each component into sensing device for sweat detection and analysis is also discussed. Finally, challenges and opportunities for wearable sweat sensors are delineated in the development of future personalized and predictive healthcare.     

Spectroscopic detection of gastrointestinal dysplasia using optical microsensors

The detection of dysplasia in the gastrointestinal tract can be performed using optical microsensors based on thin-film optical filters and silicon photodiodes. This paper describes two optical microsensors that can be used for spectroscopy data collection in two different spectral bands (one in the violet/blue region and the other in the green region) for which two optical filters were designed and fabricated. An empirical analysis of gastrointestinal spectroscopic data using these specific spectral bands is performed. The obtained results show that it is possible to accurately differentiate dysplastic lesions from normal tissue, with a sensitivity and specificity of 77.8% and 97.6%, respectively. Therefore, the developed filters can be used as a tool to aid in diagnosis. The small size of the optical microsensors can enable, in the future, integration in endoscopic capsules.     

Electrochemical microsensors

A critical review of recent developments in electrochemical microsensors is presented. The main emphasis is on chemiresistors and potentiometric microsensors. Both types of sensors have reached a degree of considerable maturity. It appears that the main future thrust can be expected in development of microfabricated sensing arrays based on these two principles.     

A wafer-level microcap array to enable high-yield microsystem packaging

Packaging represents a significant and expensive obstacle in commercializing microsystem technology (MST) devices such as microelectromechanical systems (MEMS), microopticalelectromechanical systems (MOEMS), microsensors, microactuators, and other micromachined devices. This paper describes a novel wafer-level protection method for MSTs which facilitate improved manufacturing throughput and automation in package assembly, wafer-level testing of devices, and enhanced device performance. The method involves the use of a wafer-sized microcap array. This array consists of an assortment of small caps molded onto a material with adjustable shapes and sizes to serve as protective structures against the hostile environments associated with packaging. It may also include modifications which enhance its adhesion to the MST wafer or increase the MST device function. Depending on the application, the micromolded cap can be designed and modified to facilitate additional functions, such as optical, electrical, mechanical, and chemical functions, which are not easily achieved in the device by traditional means. The fabrication and materials selection of the microcap device is discussed in this paper. The results of wafer-level microcap packaging demonstrations are also presented.     

Fabrication of Large-Area Suspended MEMS Structures Using GaN-on-Si Platform

In this letter, piezosensitive elements featuring large-size suspended gallium nitride (GaN) microstructures are fabricated with a two-step dry-release technique using the GaN-on-Si platform. The suspended microstructures are integrated with highly piezosensitive AlGaN/GaN heterostructures as sensing units to realize the GaN-based integrated microsensors. To characterize the residual-stress distribution of the fabricated microstructures, micro-Raman spectroscopy is employed. A microaccelerometer structure with a 250 times 250-mum² proof-mass area is fabricated with the proposed fabrication technique, and the piezoresponse properties of the integrated sensing elements are characterized through bending experiment.     

地面卫星信息监测分析服务系统软件设计中的关键技术

地面综合气象卫星信息监测分析服务系统是卫星系统应用的重 要组成部分。根据其功能实现的需要,通过采用基于ArcGIS的遥测信息处理、基于空间信息 的时间属性叠加存储,以及基于索引查找的海量信息定位等方法,搭建了气象卫星信息监测 分析服务系统软件设计所涉及到的地理信息与遥感信息相结合、时空一体化数据存储、海量 数据图像处理与显示等关键技术的实现方案,为该气象卫星的整体成功应用奠定了坚实的 技术基础。     

Integration of task scheduling, action planning, and control inrobotic manufacturing systems

This paper presents a novel approach for solving a challenging problem in the intelligent control of robotic manufacturing systems, i.e., the integration of low-level system sensing and control with high-level system behavior and perception. First, a newly developed event-based planning and control method will be introduced. It will then be extended to a robotic manufacturing system via a hybrid system approach. The tasks of a robotic manufacturing system usually consist of multiple segments of robotic actions, which involve both continuous and discrete types of actions. The max-plus algebra model has been proposed to model such a system. Combined with the event-based planning and control methods, both discrete and continuous actions can be planned and controlled based on the max-plus algebra model. More important, the interactions between discrete and continuous actions can be formulated analytically. A typical parts-sorting task in a robotic manufacturing system is used to illustrate the proposed approach. The experimental results clearly demonstrate the advantages of this method     

无线感知通信一体化关键技术分析

无线感知通信一体化是基于软硬件资源共享或信息共享实现感知与通信功能协同的新型信息处理技术,是6G热点技术之一。在讨论传统无线感知技术方式基础上,重点分析资源一体化、功能一体化和资源功能一体化3种无线感知通信一体化技术模式,并简要阐述了3种技术场景。围绕设备形态和作用距离等关键要素,对不同频段中一体化方案可行性进行了简要分析,并给出了统一的收发机结构设计思路。最后,针对智能体交互场景需求介绍了一体化应用思路。     

Implementation of multichannel sensors for remote biomedical measurements in a microsystems format

A novel microelectronic "pill" has been developed for in situ studies of the gastro-intestinal tract, combining microsensors and integrated circuits with system-level integration technology. The measurement parameters include real-time remote recording of temperature, pH, conductivity, and dissolved oxygen. The unit comprises an outer biocompatible capsule encasing four microsensors, a control chip, a discrete component radio transmitter, and two silver oxide cells (the latter providing an operating time of 40 h at the rated power consumption of 12.1 mW). The sensors were fabricated on two separate silicon chips located at the front end of the capsule. The robust nature of the pill makes it adaptable for use in a variety of environments related to biomedical and industrial applications.     

Decentralized structure-integrated spatial force measurement in machine tools

New manufacturing processes and extended movability of modern machine tools, such as five-axis kinematics or hexapods, increase the demand for in-process measurement of spatial forces and torques in up to 6 degrees of freedom (DoF). The approach proposed in this paper is based on the idea of integrating 6 single-axis force sensors into the machine’s structure and converting these sensor forces to spatial forces and torques at the tool centre point (TCP) using a measurement model. This concept is advantageous to costs, ruggedness and available workspace when compared to state-of-the-art 6 DoF force/torque transducers. At the same time, the achievable measuring accuracy is similar and also significantly better than the accuracy of drive current based force evaluation. On the other hand, structure and machine influences have to be addressed by suitable measurement models. This article presents design, parametrization, verification, and characterisation of these measurement models on the example of four integration concepts, two in rigid bar frameworks and two in bar kinematics. Further, experimental results are shown which are classified in comparison to a 6 DoF F/T sensor and drive current based force measurement. Finally, other influences, such as structural design and deformations, as well as the integration of sensors and models into the machine’s control software are discussed.     

Micromachined thermally based CMOS microsensors

An integrated circuit (IC) approach to thermal microsensors is presented. The focus is on thermal sensors with on-chip bias and signal conditioning circuits made by industrial complementary metal-oxide-semiconductor (CMOS) IC technology in combination with post-CMOS micromachining or deposition techniques. CMOS materials and physical effects pertinent to thermal sensors are summarized together with basic structures used for microheaters, thermistors, thermocouples, thermal isolation, and heat sinks. As examples of sensors using temperature measurement, we present micromachined CMOS radiation sensors and thermal converters. Examples for sensors based on thermal actuation include thermal flow and pressure sensors, as well as thermally excited microresonators for position and chemical sensing. We also address sensors for the characterization of process-dependent thermal properties of CMOS materials, such as thermal conductivity, Seebeck coefficient, and heat capacity, whose knowledge is indispensable for thermal sensor design. Last, two complete packaged microsystems-a thermoelectric air-flow sensor and a thermoelectric infrared intrusion detector-are reported as demonstrators     

Sensor-based robotic assembly systems: Research and applications in electronic manufacturing

The analysis, design, and evaluation of robotic systems for manufacturing applications require understanding of sensing, representation, and manipulation as well as the integration and configuration of computer processors for control of the system. Robotic assembly presents particularly complex research issues due to the physical interactions among workpieces, precise positioning, and complex geometry of the manipulations. This paper presents an overview of research in the Flexible Assembly Laboratory at Carnegie-Mellon University and describes results in force, tactile, and visual sensing, sensor-based control, gripper design, and the configuration of a testbed multirobot integrated system for experiments in assembly of electronic components, using vision for the acquisition and orientation of parts and tactile sensing for assistance in insertion tasks. A joint research program between CMU and Westinghouse Electric Corporation has resulted in the development of the Standard Electronic Assembly Station (SEAS) which integrates a variety of research concepts into a production prototype for circuit board assembly.     

Spatially-correlated neuron transistors with ion-gel gating for brain-inspired applications

In this paper, ion-gel gated transistors based on solution-processed indium-gallium-zinc-oxide (In-Ga-Zn-O) semiconductors were fabricated. These transistors consisted of a spatial distribution configuration of multi-in-plane gates. Spike pluses applied on multi-in-plane gates are analogy to massive synaptic inputs from various dendritic positions. The basic neuromorphic functions, such as potentiation or depression behaviors, synaptic plasticity and frequency-dependent filtering, were demonstrated in these devices by applied a spiking on an in-plane gate. The output signal of neuromorphic devices is greatly relevant to the gate position-correlated input signal and the spatially-correlated information processing could advance the capacity of neuromorphic performance. Orientation selectivity was a broadly investigated phenomenon. More importantly, by using the spatial summation functions of dendritic integration, the orientation identification was successfully realized in our transistor with multi-in-plane gates. The spatially-correlated neuromorphic devices are exceedingly promising for the neural information processing and sensing.     

Integrating GIS's and remote sensing image analysis systems byunifying knowledge representation schemes

The major barriers to the integration of remote sensing image analysis and geographical information system (GIS) technologies include the problems with data format, data accuracy, and system communication. This research explores a new path for achieving the integration. The three problems, which at first may seem to be independent of each other, are considered as different aspects of a problem with knowledge (information) representation and are tackled by unifying the systems on a common knowledge representation framework. Three new techniques-relational-linear quadtree, fuzzy representation method, and communication subschema-have been developed to provide such a framework     

Hybridisation of LEDs with silicon microsensors

This paper presents the experiments we performed for hybrid integration of LEDs with silicon optical readout microsensors. LEDs were face down mounted, in a silicon cavity, on the same wafer with the sensor. The edge-emitted light is coupled into SiON waveguides. The LEDs hybridization steps were included in the technological processes of two types of silicon microsensors: chemo-optical and mechano-optical sensors. The proper technological steps succession was established according to the limitation imposed by lithography on wafers with deep groves and the thermal behavior of transducing layers. The main problem we solved was the matching of all the involved processes: integrated optics, micromachining, thin-film technology, CMOS technology.     

CCD arrays for readout of electrophotographic latent images

Arrays of charge sensing elements have been fabricated for nondestructive electronic readout of latent images on electrophotographic materials. The arrays are implemented in the form of a monolithic integrated circuit in which each sensing element is a 5-μm ×5-μm MOS capacitor; 2048 such elements are arranged in a linear format with effective 5-μm element-to-element pitch. On-chip circuitry allows for multiple sampling at each sensing site for enhancing signal-to-noise ratio. The resulting signals from the sense elements are multiplexed onto charge-coupled-device (CCD) shift registers for high-speed serial readout. To allow for the small sensor-to-film gap (on the order of 10 μm) required for capacitive sensing, the chip's bond pads are recessed in deep grooves below the active array surface. The array is packaged within a hydrostatic air bearing which maintains a constant and uniform gap. The response of the array to targets of high spatial frequency recorded on various electrophotographic materials is in excellent agreement with analytical predictions     

A Fiber-Optic Bragg Grating Seismic Sensor

Here we present a fiber-optic seismic waves sensor based on in-fiber Bragg gratings. Fiber-Bragg-grating (FBG) sensors have been demonstrated to have very high sensitivity to dynamical strain and very extended dynamical response. The seismic sensing system is based on the integration of three FBGs' dynamical strain sensors in a mechanical structure acting as an inverse pendulum. Polar symmetry of the mechanical system and 120deg placement of the FBG sensors could enable directional capability of the seismic sensor. Design, manufacturing, and preliminary dynamical testing of the seismic sensor are discussed.     

Coordination mechanisms for multi-agent manufacturing systems:applications to integrated manufacturing scheduling

The advent of information technology (IT) has made today's manufacturing systems increasingly distributed. Typically such a system consists of a complex array of computer-based decision units, controllers and databases. Rather than dealing with each component individually, it is necessary to have a new paradigm for management of manufacturing systems, so that all the components and their operations can be managed in an integrated fashion. The multi-agent framework presented in this paper is such a paradigm for achieving system integration. The authors specifically emphasize the coordination mechanisms needed for ensuring the orderly operations and concerted decision making among the components-i.e., agents-of the manufacturing systems. The application of the framework to a printed circuit board manufacturing system and the performance results are also described