We review recently obtained results for CMOS (Complementary Metal Oxide Semiconductor) imaging devices used in biomedical applications. The topics include dish type image sensors, deep-brain implantation devices for small animals, and retinal prosthesis devices. Fundamental device structures and their characteristics are described, and the results of in vivo experiments are presented.

With exponentially increasing power densities due to technology scaling and ever increasing demand for performance, chip temperature has become an important issue that limits the performance of computer systems. Typically, it is essential to use a set of on-chip thermal sensors to monitor temperatures during the runtime. The runtime thermal measurements are then employed by dynamic thermal management techniques to manage chip performance appropriately. In this paper, we propose an inverse distance weighting method based on a dynamic Voronoi diagram for the reconstruction of full thermal characterization of integrated circuits with non-uniform thermal sensor placements. Firstly we utilize the proposed method to transform the non-uniformly spaced samples to virtual uniformly spaced data. Then we apply three classical interpolation algorithms to reconstruct the full thermal signals in the uniformly spaced samples mode. To evaluate the effectiveness of our method, we develop an experiment for reconstructing full thermal status of a 16-core processor. Experimental results show that the proposed method significantly outperforms spectral analysis techniques, and can obtain full thermal characterization with an average absolute error of 1.72% using 9 thermal sensors per core.

We have fabricated VDP (van der Pauw) stress sensors on (111) silicon surfaces. This work focuses on a study of strain effects in VDP stress sensors, which were generally ignored in previous works, for the precise measurements of die stresses in electronic packages. The stress sensitivity was observed to be approximately 10% larger for p-type VDP sensors compared to n-type VDP sensors.

In this letter, we propose a novel approach using wireless sensor networks (WSNs) to enhance the safety and efficiency of four-way stop-sign-controlled (FWSC) intersections. The proposed algorithm provides right of way (RoW) and crash avoidance information by means of an intelligent WSN system. The system is composed of magnetic sensors, embedded in the center of a lane, with relay nodes and a base station placed on the side of the road. The experimental results show that the vehicle detection accuracy is over 99% and the sensor node battery life expectancy is over 3 years for traffic of 5,800 vehicles per day. For the traffic application we consider, a strong effect is observed as the projected conflict rate was reduced by 72% compared to an FWSC intersection operated with only driver perception.

This paper focuses on optical integration technology and its application in optical microsensors used in biomedical fields. The integration is based on the hybrid integration approach, achieving high performance, small size and weight, and lower cost. First, we describe the key technologies used in hybrid integration, namely passive alignment technology, low temperature bonding technology, and packaging technology for realizing advanced microsensors. Then, we describe an integrated laser Doppler flowmeter that can monitor blood flow in human skin.

In this paper we present an intelligent active video surveillance system currently adopted in two different application domains: railway tunnels and outdoor storage areas. The system takes advantages of the integration of Artificial Neural Networks (ANN) and symbolic Artificial Intelligence (AI). This hybrid system is formed by virtual neural sensors (implemented as WiSARD-like systems) and BDI agents. The coupling of virtual neural sensors with symbolic reasoning for interpreting their outputs, makes this approach both very light from a computational and hardware point of view, and rather robust in performances. The system works on different scenarios and in difficult light conditions.

The paper reviews recent advances in on-body antennas and propagation under a joint UK EPSRC research project between Queen Mary College, University of London and University of Birmingham. The study of on-body radio propagation has been extended by using various small antennas. The effect of antenna size, gain and radiation patterns on on-body channel characteristics has been studied. A practical wearable sensor antenna design is presented and it is demonstrated that a global simulation including sensor environment and human body is needed for accurate antenna characterisation. A 3D animation design software, POSER 6 has been used together with XFDTD to predict the on-body path loss variation due to changes in human postures and human motion. Finally, a preliminary study on the feasibility of a diversity scheme in an on-body environment has been carried out.

Automated capture and retrieval of experiences at home is interesting due to the wide variety and personal significance of such experiences. We present a system for retrieval and summarization of continuously captured multimedia data from Ubiquitous Home, a two-room house consisting of a large number of cameras and microphones. Data from pressure based sensors on the floor are analyzed to segment footsteps of different persons. Video and audio handover are implemented to retrieve continuous video streams corresponding to moving persons. An adaptive algorithm based on the rate of footsteps summarizes these video streams. A novel method for audio segmentation using multiple microphones is used for video retrieval based on sounds with high accuracy. An experiment, in which a family lived in this house for twelve days, was conducted. The system was evaluated by the residents who used the system for retrieving their own experiences; we report and discuss the results.

We have been investigating a new class of ubiquitous services, called Activity Logging, which takes advantage for private and public sensors and the RFID tags on real-world objects. The purpose of Activity Logging is to digitally record users' interests with real-world objects and users' context to describe the users' activity. Such digital information acquired from a range of sensors and tags, if being accumulated, forms a great data source for users to recall their activities later or to share the activities with others. This paper explores the design space to realize Activity Logging, and proposes a simple mobile device called Activity Recorder that marries public and private sensors to provide a powerful Activity Logging service. An Activity Recorder contains a range of private sensors, and has communication capability to work with public sensors around the user.

With advent of the ubiquitous network era and due to recent progress of III-V nanotechnology, the present III-V heterostructure microelectronics will turn into what one might call III-V heterostructure nanoelectronics, and may open up a new future in much wider application areas than today, combining information technology, nanotechnology and biotechnology. Instead of the traditional top-down approach, new III-V heterostructure nanoelectronics will be formed on nanostructure networks formed by combination of top-down and bottom-up approaches. In addition to communication devices, emerging devices include high speed digital LSIs, various sensors, various smart-chips, quantum LSIs and quantum computation devices covering varieties of application areas. Ultra-low power quantum LSIs may become brains of smart chips and other nano-space systems. Achievements of new functions and higher performances and their on chip integration are key issues. Key processing issue remains to be understanding and control of nanostructure surfaces and interfaces in atomic scale.

This paper offers an initial analysis of economic and market issues in the development and deployment of mobile remote physiological monitoring services for medical patients through wireless wearable sensors and actuators. Examining the characteristics of the service technologies and related industries, this study focuses on the structure, participants and roles of standardisation of the layers within the emerging mobile remote physiological monitoring industry. The study concludes that the structure of the emerging mobile remote physiological monitoring industry will be oriented about service provision, be integrated with other personal / patient data storage services and be heavily influenced by the interplay of technological developments, the health market structure, existing players and regulation. Additionally, the keys players are likely to be the system integrators and service providers concentrating on large institutional customers. A focus of the paper is analysing both the causes and implications of a modular, horizontally layered industry structure likely to result from the mix of technologies, suppliers and customers as this market develops. The paper discusses why, although horizontal specialisation is the most likely outcome, there is little risk of key layers becoming commoditised. The paper also discusses the appropriate types and levels of standardisation and equipment certification activities that should be encouraged, along with from which groups and industries the pressure for these will come.

Some electromechanical devices and systems produced using MEMS fabrication processes are detailed. Two precision measurement metrologies for inspecting electromechanical products are also described. As the trend of electromechanical devices has been towards smaller and smaller sizes possessing robust mechanisms and powerful functions, micro-electric-mechanical system (MEMS) devices are becoming more the choice for meeting such requirements. Three MEMS examples are discussed in detail in this paper: CMOS compatible sensors, RF/microwave components, and packaged and integrated passive devices. The design thinking of a new free-fall sensor, which is an accelerometer and possesses a surprisingly low frequency response and broad bandwidth, is mentioned. In addition, an AVID (dvanced ibrometer/nterferometer evice) system for measuring tiny displacement as well as a Morphinscope system that has the advantage of a confocal microscope combined with a photon tunneling microscope and both developed by NTU's MEMS/NEMS group, are discussed. The excellent sensing ability of the free-fall sensor and the accuracy resolution of the two measurement systems are proved by experimental verification.

Two types of biomimetic chemical sensing systems are reviewed. One is an electronic nose and tongue which can recognize odor or taste from the output pattern of arrayed chemical sensors with different but overlapped specificities. The other is a chemical plume tracing system which has been developed to mimic the moth behavior in tracing the sexual pheromone from a female. We have created an odor/gas tracing robot and a compass, both of which can detect the direction from which an odor/gas is issuing.

We describe FMCW reflectometry for characterization of long optical fibers by using an external-cavity laser diode as a light source. Since the optical path difference between the reference beam and the reflected beam from the optical fiber under test is much longer than the coherence length of the light source, the reference and the reflected beams are phase-decorrelated. As a result, the beat spectrum between the reference and the reflected beams is measured. In the phase-decorrelated FMCW reflectomety, the spatial resolution is enhanced by narrowing the spectral linewidth of the light source and increasing the repetition frequency of the optical frequency sweep as well as increasing the chirping range of the optical frequency sweep. In the experiments, an external-cavity DFB laser is used as a narrow linewidth light source, and the optical frequency is swept by minute modulation of the external cavity length. Long single mode optical fibers are characterized, and the maximum measurement range of 80 km is achieved, and the spatial resolutions of 46 m, 100 m and 2 km are achieved at 5 km, 11 km and 80 km distant, respectively. The Rayleigh backscattering is clearly measured and the propagation loss of optical fiber is also measured. The optical gain of an erbium-doped optical fiber amplifier (EDFA) is also estimated from the change in the Rayleigh backscattering level in the optical fiber followed after the EDFA.

We will discuss performance optimization of strain and temperature sensors based on long period fiber gratings (LPFGs) through control of the temperature sensitivity of the resonant peak shifts. Distinction between the effects of strain and temperature is a major concern for applications to communication and sensing. This was achieved in this work by suppressing or enhancing the temperature sensitivity by adjusting the doping concentrations of GeO2 and B2O3 in the core or cladding. The LPFGs were fabricated with a CO2 laser by the mechanical stress relaxation and microbending methods. The optimized temperature sensitivities were 0.002 nm/ for the suppressed case and 0.28 nm/ for the enhanced case, respectively. These LPFGs were used for simultaneous measurement of strain and temperature. The result indicates the rms errors of 23 µstrain for the strain and 1.3 for the temperature.

This paper describes the implementation of a Bragg grating-based strain-monitoring system on the Viaduc des Vaux bridge during its construction in 1997 and 1998. The bridge was constructed in a cantilevered, push/pull incremental launching method, and data obtained from two tests were shown to reveal interesting features of the box-girder strain response during the push and pull phases, particularly with regard to limit loads and local buckling. When appropriate, data were compared to data obtained from conventional resistive strain gages and from simple analytical models.

A short review of distributed and multiplexed sensor technology, based on fibre gratings, is given. This is followed by details of more specific work in this area at the University of Southampton, particularly grating fabrication, distributed and multiplexed addressing and important practical aspects such as temperature and strain discrimination. The paper concludes with a short discussion of the problems that must be avoided in order to construct viable systems for engineering requirements.

Compact intra-cavity spectroscopic measurements may be obtained with any material that has an absorption signature under the gain bandwidth of a fiber laser. Experiments have demonstrated that compared with a regular absorption scheme, an increase in sensitivity is achieved when using the intra-cavity configuration. The practical limit for this enhancement is given by the fiber laser noise. Since intra-cavity spectroscopy is essentially a single beam technique, the application of dual-beam noise reduction techniques is not possible. However, considering that a single-mode fiber can support two modes of polarization, we have used a polarization beam splitter to create two independent cavities (x and y polarization) with the same noise, one cavity of which contains the absorber. For the first time, this permits the convenient use of Balanced Ratiometric Detection in conjunction with an intra-cavity absorption arrangement.

A novel optical technique for the measurement of temperature is proposed. This is accomplished by depositing alternating 1/4 wave layers of silicon nitride and silicon-rich silicon nitride at the end of an optical fiber. These layers of alternating refractive index form the equivalent of a Bragg grating of a high temperature material. When the fiber and the Bragg grating are heated, the Bragg stack expands, and there is a change in the reflective peak wavelength of this wave stack. Thus, the wavelength of peak reflectivity is a function of temperature. Currently, the 15 nm spectral width of the Bragg stacks is achieved in our laboratory, which is conveniently monitored with a CCD solid state spectrometer and the temperature sensor probes can be also multiplexed at separated specific reflection wavelength. In the experiment, the temperatures in excess of 1,100 centigrade have been measured with a resolution of less than 3 centigrade degree.

This paper reviews the use of fiber optic sensors for downhole monitoring in the oil and gas industry. Due to their multiplexing capabilities and versatility, the use of Bragg grating sensors appears to be particularly suited for this application. Several types of transducer have been developed, each of which can be addressed along a single (common) optical fiber in the well and read-out using a common surface instrumentation system.