CMOS fingerprint sensor electrostatic modeling

The use of Biometrics in personal identification is an important emerging technology in modern electronic society. Fingerprints are one of the most popular biometric technologies, currently used in majority of biometric applications. In recent years, solid-state capacitive fingerprint sensors which image fingerprints using Silicon CMOS Technology are gaining much acceptance in the market. This research work is carried out to quantify and explore approaches for achieving improved sensitivity of the capacitive imaging process through reduction of parasitic capacitances and sensor cell scaling for future generation devices. Evaluation of sensor cell and array geometries was completed using a commercial 2-D electrostatic field solver. The modeling activities performed include analysis of sensor cell and sensor plate size, their relationships, evaluation of ESD ring coupling, and exploration of cell and array layout approaches for achieving reduced parasitic capacitance

Development of new techniques for the recovery of conductive fingermark

Fingerprints are an important type of evidence within the practice of forensic investigation and are growing in importance in terms of security. Fingerprints as evidence are one of the most highly regarded forms of evidence in court. The uniqueness of fingerprints and the admissibility of such evidence has made fingerprints a vital part of forensic investigation. This being said the techniques used for recovering such evidence have not been developed much since the first uses in the 19th and 20th centuries. The modern-day role of fingerprints is becoming more apparent in technology and biosecurity, but this role has not yet been considered when recovering fingerprints throughout a crime. In order to develop a recovery technique that would allow application within technology, a level of conductivity is required to activate many of the sensors used in order to strengthen the level of security. This research highlights there is a way of developing existing techniques implemented within forensic investigation in a way that will consider this technological application. By finding a material that will conduct the current from a human body and capture the details of a fingerprint, a device may be unlocked by someone other than the electronic devices user. The success of this across various surfaces and device types could lead to the development of standard practices within forensic investigation, allowing the uses of such recovered fingermarks to be used more routinely throughout crime scene investigations

Optical Methods in Sensing and Imaging for Medical and Biological Applications

The recent advances in optical sources and detectors have opened up new opportunities for sensing and imaging techniques which can be successfully used in biomedical and healthcare applications. This book, entitled ‘Optical Methods in Sensing and Imaging for Medical and Biological Applications’, focuses on various aspects of the research and development related to these areas. The book will be a valuable source of information presenting the recent advances in optical methods and novel techniques, as well as their applications in the fields of biomedicine and healthcare, to anyone interested in this subject

On-chip optical sensors

Adding more functionality to chips is an important trend in the advancement of technology. During the past couple of decades, integrated circuit developments have focused on keeping Moore\u27s Law alive More of Moore . Moore\u27s law predicts the doubling of the number of transistors on an integrated circuit every year. My research objectives revolve around More than Moore , where different functionalities are sought to be integrated on chip. Sensing in particular is becoming of paramount importance in a variety of applications. Booming healthcare costs can be reduced with early diagnosis, which requires improved sensitivity and lower cost. To halt global warming, environmental monitoring requires miniature gas sensors that are cheap enough to be deployed at mass scale. First, we explore a novel silicon waveguide platform that is expected to perform well as a sensor in comparison to the conventional 220 nm thick waveguide. 50 and 70 nm shallow silicon waveguides have the advantage of easier lithography than conventional 220 nm thick waveguides due to the large minimum feature size required of 1 µm. 1 µm wide waveguides in these shallow platforms are single mode. A multi-mode interference device is designed in this platform to function as the smallest MMI sensor, giving sensitivity of 427 nm / refractive index unit (RIU) at a length of 4 mm. The silicon photonic MMI sensor is based on detecting refractive index changes. Refractometric techniques such as the MMI sensor require surface functionalization to achieve selectivity or specificity. Spectroscopic methods, usually reserved for material characterization in a research setting, can be adapted for highly specific label-free sensing. Chapter 4 explores the use of a highly doped III-V semiconductor for on chip infrared spectroscopy. Finite element method and finite different time domain were both used to design a plasmonic slot waveguide for gas sensing. On chip lasers and detectors have been designed using InAs. While InAs is still considered more expensive than silicon, the electronics industry expects to start incorporating more materials in standard fabrication processes, including III-V semiconductors for their superior properties including mobility. Thus, experimental realization of this sensor is feasible. A drawback with infrared spectroscopy is that it is difficult to use with biological fluids. Chapter 5 explores the use of Raman spectroscopy as a sensing method. To adapt Raman spectroscopy for sensing, the most important task is to enhance the Raman signal. The way the Raman signal is generated means that the number of photons is generally very low and usually bulk material or concentrated fluids are used as samples. To measure low concentrations of a probe molecule, the probe molecule is placed on a surface enhanced Raman spectroscopy (SERS) substrate. A typical SERS substrate is composed of metal nanostructures for their surface plasmon resonance property, which causes a large amplification in the electric field in particular hot spots. By decorated silicon nanowires with silver nanoparticles, an enhancement factor of 1011 was realized and picomolar concentrations of pyridine were detected using Raman spectroscopy. In conclusion, this thesis provides new concepts and foundations in three directions that are all important for on chip optical sensing. First, silicon photonics is the technology of choice that is nearest to the market and a multi-mode interference sensor based on shallow silicon waveguides was designed. Further work can explore how to cascade such MMIs to increase sensitivity without sacrificing the free spectral range. Second, infrared plasmonics is a promising technology. Before semiconductor plasmonics, on chip devices operated in the visible or near IR and then microwave region of the electromagnetic spectrum. By using highly doped semiconductors, it is possible to bridge the gap and operate with mid-infrared wavelengths. The implications are highlighted by designing a waveguide platform that can be used for next generation on chip infrared spectroscopy. Third, Raman spectroscopy was exploited as a sensing technique by experimental realization of a SERS substrate using equipment-free fabrication methods

Technology Survey to Support Revision to the Remedial Investigation/Feasibility Study Work Plan for the 200­-SW­-2 Operable Unit at the U.S. Department of Energy’s Hanford Site

A survey of technologies was conducted to provide information for a Data Quality Objectives process being conducted to support revision of the Remedial Investigation/Feasibility Study Work Plan for the 200-SW-2 Operable Unit. The technology survey considered remediation and characterization technologies. This effort was conducted to address, in part, comments on the previous version of the Remedial Investigation/Feasibility Study Work Plan for the 200-SW-2 Operable Unit as documented in 200­SW­1 and 200­SW­2 Collaborative Workshops―Agreement, Completion Matrix, and Supporting Documentation. By providing a thorough survey of remediation and characterization options, this report is intended to enable the subsequent data quality objectives and work plan revision processes to consider the full range of potential alternatives for planning of the Remedial Investigation/Feasibility Study activities

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Department of Energy EngineeringElectronic skins (e-skins) enabling to detect various mechanical/chemical stimuli and environmental conditions by converting into various electrical and optical signals have attracted much attentions for various fields including wearable electronics, intelligent/medical robotics, healthcare monitoring devices, and haptic interfaces. Conventional e-skins have been widely used for the realization of these applications, however it is still considered that new e-skins with enhanced sensor performances (i.e. sensitivity, flexibility, multifunctionality, etc.) should be developed. In accordance with these demands, two approaches to explore novel functional materials or to modify device architectures have been introduced for enhancing sensor performance and acquiring multifunctional sensing capabilities. Firstly, a synthesis of multifunctional materials combined with conductive fillers (carbon nanotube, graphene oxide) and functional polymer matrix (i.e. ferroelectric polymer, elastomer) can provide the multimodal sensing capability of various stimuli and stretchability. Secondly, controlling design of device structures into various micro/nanostructures enables a significant improvement on sensing capabilities of e-skins with sensitivity and multidirectional force sensing, resulting from structural advantages such as large surface area, effective stress propagation, and anisotropic deformation. Therefore, a demonstration of e-skin combined with the functional composites and uniquely designed microstructures can offer a powerful platform to realize ideal sensor systems for next generation applications such as wearable electronics, healthcare devices, acoustic sensor, and haptic interface devices. In this thesis, we introduce the novel multifunctional and high performance electronic skins combined with various types of composite materials and nature-inspired 3D microstructures. Firstly, Chapter 1 briefly introduces various types of e-skins and the latest research trends of microstructured e-skins and summarizes the key components for their promising application fields. In chapters 2 and 3, mimicked by interlocking system between epidermal and dermal layers in human skin, we demonstrate the piezoresistive e-skins based on CNT/PDMS composite materials with interlocked microdome arrays for great pressure sensitivity and multidirectional force sensing capabilities. In chapter 4, we conduct in-depth study on giant tunneling piezoresistance in interlocking system and investigate systematically on the geometrical effect of microstructures on multidirectional force sensitivity and selectivity in interlocking sensor systems. In chapter 5, we demonstrate the ferroelectric e-skin that can detect and discriminate the static/dynamic touches and temperature inspired by multi-stimuli detection of various mechanoreceptors in human skin. Using the multifunctional sensing capabilities, we demonstrated our e-skin to the temperature-dependent pressure monitoring of artery vessel, high-precision acoustic sound detection, and surface texture recognition of various surfaces. In chapter 6, we demonstrate the linear and wide range pressure sensor with multilayered composite films having interlocked microdomes. In chapter 7, we present a new-concept of e-skin based on mechanochromic polymer and porous structures for overcoming limitations in conventional mechanochromic systems with low mechanochromic performances and limited stretchability. In addition, our mechanochromic e-skins enable the dual-mode detection of static and dynamic forces without any external power. Our e-skins based on functional composites and uniquely designed microstructures can provide a solid platform for next generation eskin in wearable electronics, humanoid robotics, flexible sensors, and wearable medical diagnostic systems.clos

Research on flexible display at ulsan national institute of science and technology

Displays represent information visually, so they have become the fundamental building block to visualize the data of current electronics including smartphones. Recently, electronics have been advanced toward flexible and wearable electronics that can be bent, folded, or stretched while maintaining their performance under various deformations. Here, recent advances in research to demonstrate flexible and wearable displays are reviewed. We introduce these results by dividing them into several categories according to the components of the display: active-matrix backplane, touch screen panel, light sources, integrated circuit for fingerprint touch screen panel, and characterization tests; and we also present mechanical tests in nano-meter scale and visual ergonomics research