CMOS-based Sensor Research Articles

Development of a 3-D X-Ray Micro-tomography System and its Application to Trabecular Bone/Cement Interface

In recent years,the interface analysis of micro-structure based objects is an important research in osteoporosis,vascular imaging since a 3-D X-ray micro-tomography system was developed. However,the micro-tomographic image shows the white-out appearance in case of imaging of similar density objects with low energy X-ray.Therefore these images must be analyzed about the interface between micro-sucture based objects for its application to biomechanical study. Many published studies suggested approximately assumed model of interface and predicted mechanical failure by means of Finite Element Method (FEM) but these FEM analysis has not used for modeling the real structure and interface between objects such as roughness,voids and pores of objects.We developed micro-tomography system and suggest the application of micro-tomographic image for predicting mechanical failure at the interface.The micro-tomography system consists of a 5µm micro-focus X-ray tube,a CMOS-based image sensor and a rotating sample holder controlled by a precision motor. CMOS image sensor has 62×62 mm2 sensing area and uses opticallenses system for increasing resolution.The sample which was manufactured by implanting cement in a pig hip bone was used and its fracture is considered to be an important cause of loosening of hip joint replacement in orthopedic implants. A Feldkamp’s cone-beam reconstruction algorithm on the equispatial detector case was used for bone/cement 3D volume data and the analysis of a trabecular bone/cement interface containing white-out appearance was performed by using multiple criterion segmentation of region and volume. Finally,the segmented data can be used for fracture prediction of FEM by determining node ofhexahedron meshing.In this paper,we present development of a 3-D cone beam micro-tomographic system with CMOS image sensor and its application to a complex structure of a trabecular bone and implanted cement for predicting the failure mechanism of orthopedic implants due to stress and pressure. We wi1l also show that how the segmented data is used as geometric input data of I-DEAS for FEM simulation.

CMOS Single Chip Gas Detection Systems — Part I

AbstractThe current trend to control indoor air‐quality and to monitor environmental pollution has created a strong demand for miniaturized and inexpensive gas sensors for volatile organic compounds (VOCs). Gas sensor arrays based on industrial CMOS‐processes combined with post‐CMOS micromachining (CMOS MEMS) are a promising approach to low‐cost sensor devices. In this article, the state of research of CMOS‐based gas sensor systems is reviewed, and a platform technology is described, which provides the possibility of monolithically integrating several different transducers on a single chip. A design environment, batch‐fabrication processes, and fast testing procedures were developed to realize an example single‐chip gas detection system. The chip includes the transducers, their biasing circuitry, reference elements, a digital interface, and a temperature sensor. The three polymer‐based transducers and their interface electronics will be detailed in the second part of this article [1].

Using Reactands in CMOS-based Calorimetric Sensors: New Functional Materials for Electronic Noses

Using Reactands in CMOS-based Calorimetric Sensors: New Functional Materials for Electronic Noses

A CMOS-compatible 2-D vertical Hall magnetic-field sensor using active carrier confinement and post-process micromachining

This work presents a CMOS-based magnetic-field sensor for the detection of magnetic-field vector components that occur parallel to the chip surface. The device employs two vertical Hall plate structures embedded in the substrate orthogonal to each other. The sensor is fabricated using a standard 3 μm CMOS process provided by a commercial integrated circuit (IC) manufacturer, and a maskless post-process bulk-micromachining step. The sensor makes use of standard p+ implants to bound the plate region for the purposes of: (a) actively confining majority carriers to a narrow channel, thereby enhancing sensitivity; and (b) acting as an etch-stop layer. The micromachined cavities act to reduce detrimental cross-sensitivity effects. Sensitivity is found to vary with negatively increasing p+ confinement voltage, but appears to saturate due to a pinch-off effect.

Tin oxide gas sensor fabricated using CMOS micro-hotplates and in-situ processing

A monolithic tin oxide (SnO/sub 2/) gas sensor realized by commercial CMOS foundry fabrication (MOSIS) and postfabrication processing techniques is reported. The device is composed of a sensing film that is sputter-deposited on a silicon micromachined hotplate. The fabrication technique requires no masking and utilizes in situ process control and monitoring of film resistivity during film growth. Microhotplate temperature is controlled from ambient to 500 degrees C with a thermal efficiency of 8 degrees C/mW and thermal response time of 0.6 ms. Gas sensor responses of pure SnO/sub 2/ films to H/sub 2/ and O/sub 2/ with an operating temperature of 350 degrees C are reported. The fabrication methodology allows integration of an array of gas sensors of various films with separate temperature control for each element in the array, and circuits for a low-cost CMOS-based gas sensor system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optimization of magnetotransistor structure in CMOS technology

Experimental results are presented for the comparison of a novel CMOS-based magnetic sensor and a lateral magnetotransistor. Results indicating a dramatic increase in sensitivity are given, and a linear response is obtained. An improvement in the device sensitivity of four times was measured, and a maximum sensitivity of 200%/T was found. An explanation for the increase in sensitivity is proposed and confirmed by an analysis of both the electrical and magnetic characteristics of both devices. This explanation attributes the increase in sensitivity to the inhibition of laterally injected electrons from the emitter edges. This is achieved by the placement of p/sup +/ stripes along the emitter edges. Additional experimental results show that an increase in sensitivity was found as the emitter length of the magnetic sensor was shortened.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>