Real-Time Monitoring of Epitaxial Processes by Parallel-Polarized Reflectance Spectroscopy

MRS Bulletin ◽  
1995 ◽  
Vol 20 (5) ◽  
pp. 49-55 ◽  
Author(s):  
Nikolaus Dietz ◽  
Klaus J. Bachmann
Keyword(s):  
Real Time ◽  
Low Cost ◽  
Normal Incidence ◽  
Optical Probe ◽  
Reflectance Spectroscopy ◽  
Industrial Applications ◽  
Monitoring And Control ◽  
Real Time Monitoring ◽  
Spectral Ellipsometry ◽  
Precise Control

The engineering of advanced micro-electronic circuits, optoelectronic devices, and integrated optical circuits requires precise control of the lateral dimensions and thicknesses of device features and of the stoichiometry and doping of epitaxial semiconductor regions. This is preferably achieved by real-time monitoring and control of the individual deposition and etching processes that constitute the processing sequence. The use of optical probe techniques for the real-time monitoring of etching and/or growth processes is favored because of their nondestructive character and their potential use in real-time feedback control. Some of these methods are ideal in monitoring the overall growth process and/or substrate temperature in industrial applications, requiring low cost and maintenance. For example, in situ reflectance-spectroscopy methods, such as dynamic optical reflectivity (DOS), spectral-resolved normal incidence reflectance spectroscopy (MRS), or pyrometric interferometry (PI), are successfully applied to various deposition processes and provide information on both the growth rate and the composition of the deposits. However, small changes in the reflectance (because of chemical interactions at the surface of the films with the reactants supplied from the vapor phase) are of the order of 10−3 to 10−4 and are hardly observable with normal-incidence reflectance techniques because of the high reflectivity of substrate/film interface, which is typically of the order of 40%–60% for many semiconductors.In order to increase the sensitivity to surface- and interface-related growth properties, alternative optical-observation methods such as reflectance difference spectroscopy (RDS), surface photoabsorption (SPA), and spectral ellipsometry (SE) have been developed.

scholarly journals Low-cost wireless sensor network applied to real-time monitoring and control of water consumption in residences

2019 ◽  
Vol 14 (6) ◽  
pp. 1
Author(s):  
Arnon Jadir Rodrigues Alves ◽  
Leandro Tiago Manera ◽  
Marcel Veloso Campos
Keyword(s):  
Wireless Sensor Network ◽  
Real Time ◽  
Sensor Network ◽  
Water Consumption ◽  
Mobile Application ◽  
Low Cost ◽  
Wireless Sensor ◽  
Monitoring And Control ◽  
Real Time Monitoring ◽  
And Control

The objective of this work is to explore the implementation of a low-cost real-time monitoring and control of water consumption together with a user feedback interface. Water usage information will be available in a cloud storage and can be accessed through a mobile application. The collected data allows access and supervision of both client- and water concessionaire. Project feasibility is analyzed in terms of hardware and software, as well as each element required for the design. The simulations were carried out with the purpose of verifying system operation, considering the following metrics: transmission rate, signal strength and transmission quality. After the simulations, the hardware and software were integrated, and the final result was presented through a mobile application. This work presents and applies a design and development methodology of Wireless Sensor Network (WSN) using Internet of Things (IoT) technologies and Smart City in water-distribution systems.

Measuring Optical Properties of Advanced Nano/Micro-Periodic Structures Fabricated by Multi-Exposure Interference Lithography

2020 ◽  
Author(s):  
Shuzo Masui ◽  
Masaki Michihata ◽  
Kiyoshi Takamasu ◽  
Satoru Takahashi
Keyword(s):  
Periodic Structures ◽  
Low Cost ◽  
Industrial Applications ◽  
Interference Lithography ◽  
High Dispersion ◽  
Optical Elements ◽  
Precise Control ◽  
Periodic Grating ◽  
Interference Fringes ◽  
Multiple Interference

Abstract Functional optical elements based on nano/micro-periodic structures have attracted much attention. Since the fabrication of these dual-periodic structures requires precise control of periodicity, the semiconductor process such as an electron beam lithography has been mainly employed. However, these techniques have problems with expensive and low throughput for industrial applications. Therefore, there remains a need for low cost and high throughput fabrication methods of dual-periodic structures. Then we developed a multi-exposure interference lithography (MEIL) system using rotational Lloyd’s mirror interferometer to overcome these problems. The advantages of interference lithography are a large processing area and low cost. Our developed rotational Lloyd’s mirror setup enables us to a highly precise superposition of multiple interference fringes by multi-exposure. Furthermore, we developed a measurement setup for reflective diffractive elements using a two axial rotating stage and measured the diffraction properties of the fabricated dual-periodic diffraction gratings. In this paper, as a demonstration, we succeeded in the fabrication of high-dispersion diffraction grating with an enhanced diffraction efficiency of the −3rd order light. The fabricated shapes have a periodicity of 1997 nm and 665 nm. Furthermore, it was confirmed that the intensity of the −3rd order light was enhanced by about 10 times compared to the single periodic grating.

scholarly journals Shaping Streamflow Using a Real-Time Stormwater Control Network

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2259 ◽  
Author(s):  
Abhiram Mullapudi ◽  
Matthew Bartos ◽  
Brandon Wong ◽  
Branko Kerkez
Keyword(s):  
Real Time ◽  
Control Strategies ◽  
Low Cost ◽  
Control Network ◽  
Monitoring And Control ◽  
Set Point ◽  
Smart Water ◽  
Decay Times ◽  
Retention Basins ◽  
Scale Control

“Smart” water systems are transforming the field of stormwater management by enabling real-time monitoring and control of previously static infrastructure. While the localized benefits of active control are well-established, the potential for system-scale control of watersheds is poorly understood. This study shows how a real-world smart stormwater system can be leveraged to shape streamflow within an urban watershed. Specifically, we coordinate releases from two internet-controlled stormwater basins to achieve desired control objectives downstream—such as maintaining the flow at a set-point, and generating interleaved waves. In the first part of the study, we describe the construction of the control network using a low-cost, open-source hardware stack and a cloud-based controller scheduling application. Next, we characterize the system’s control capabilities by determining the travel times, decay times, and magnitudes of various waves released from the upstream retention basins. With this characterization in hand, we use the system to generate two desired responses at a critical downstream junction. First, we generate a set-point hydrograph, in which flow is maintained at an approximately constant rate. Next, we generate a series of overlapping and interleaved waves using timed releases from both retention basins. We discuss how these control strategies can be used to stabilize flows, thereby mitigating streambed erosion and reducing contaminant loads into downstream waterbodies.

scholarly journals Non-intrusive vital sign monitoring using an intelligent pillow based on a piezoelectric ceramic sensor

2020 ◽  
Vol 15 ◽  
pp. 155892502097726
Author(s):  
Wei Wang ◽  
Zhiqiang Pang ◽  
Ling Peng ◽  
Fei Hu
Keyword(s):  
Heart Rate ◽  
Real Time ◽  
Piezoelectric Ceramic ◽  
Low Cost ◽  
Body Movement ◽  
Vital Signs ◽  
High Heart Rate ◽  
Detection Accuracy ◽  
Processing Unit ◽  
Real Time Monitoring

Performing real-time monitoring for human vital signs during sleep at home is of vital importance to achieve timely detection and rescue. However, the existing smart equipment for monitoring human vital signs suffers the drawbacks of high complexity, high cost, and intrusiveness, or low accuracy. Thus, it is of great need to develop a simplified, nonintrusive, comfortable and low cost real-time monitoring system during sleep. In this study, a novel intelligent pillow was developed based on a low-cost piezoelectric ceramic sensor. It was manufactured by locating a smart system (consisting of a sensing unit i.e. a piezoelectric ceramic sensor, a data processing unit and a GPRS communication module) in the cavity of the pillow made of shape memory foam. The sampling frequency of the intelligent pillow was set at 1000 Hz to capture the signals more accurately, and vital signs including heart rate, respiratory rate and body movement were derived through series of well established algorithms, which were sent to the user’s app. Validation experimental results demonstrate that high heart-rate detection accuracy (i.e. 99.18%) was achieved in using the intelligent pillow. Besides, human tests were conducted by detecting vital signs of six elder participants at their home, and results showed that the detected vital signs may well predicate their health conditions. In addition, no contact discomfort was reported by the participants. With further studies in terms of validity of the intelligent pillow and large-scale human trials, the proposed intelligent pillow was expected to play an important role in daily sleep monitoring.

Sign in / Sign up

Export Citation Format

Share Document