Browsing by Subject "Wireless sensor"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Design and production of an energy harvesting wireless sensor(2013-05) Bar, Farris Ahmad; Abraham, Jacob A.The widespread deployment of wireless sensors in our homes, offices, factories and infrastructure has opened the door for system designers to create novel approaches for powering wireless sensor nodes. In recent years, energy harvesting has emerged as the power supply of choice for embedded system designers, enabling wireless sensors to be used in applications that previously were not feasible with conventional battery-powered designs. This report details the design and development of an energy harvesting wireless sensor from concept to production. Design constraints included the requirement to operate reliably in a wide variety of environments, the use of commercially available components, and a visually appealing form factor. The result is a very power-efficient, solar-powered wireless sensor that measures temperature, voltage, and illumination level at the solar cell and has an ultra slim form factor.Item Development of non-contact passive wireless sensors for detection of corrosion in reinforced concrete bridge decks(2013-12) Abu-Yosef, Ali Emad; Wood, Sharon L.Corrosion of embedded reinforcement is the leading form of deterioration affecting the integrity of reinforced and prestressed concrete bridge members around the world. If undetected, corrosion can limit the service life of the bridge and lead to expensive repairs. The research team at the University of Texas at Austin has developed a new class of passive wireless corrosion sensors. The noncontact (NC) sensor platform provides an economical and nondestructive means for detecting corrosion initiation within concrete. The sensor is powered through the inductive coupling to an external mobile reader that can be handheld or mounted on a vehicle. It is envisioned that the four-dollar sensor will be embedded in concrete during construction and interrogated sporadically over the service life of the structure. The sensor output can be used to detect corrosion initiation within concrete and is expected to enhance the quality information collected during qualitative routine bridge inspections. The NC sensor prototype consists of a resonant circuit that is inductively coupled to a sacrificial transducer. Corrosion of the sacrificial element alters the measured sensor response and is used to detect corrosion within concrete. Electrochemical evaluations were conducted to ensure that the sacrificial element exhibited identical response as the reinforcement steel. In addition, the results of extensive experimental parametric studies were used in conjunction with circuit and electromagnetic finite element models to optimize the NC sensor design. Long-term exposure tests were used to evaluate the reliability of the passive noncontact sensors. Sensors were embedded in reinforced concrete specimens and successfully detected the onset of corrosion in the adjacent reinforcement. Unlike the traditional corrosion evaluation methods, such as half-cell potentials, the sensors output was insensitive to environmental variations.Item Improvements to wireless, passive sensors for monitoring conditions within reinforced concrete structures(2010-08) Chou, Chih-Chieh; Wood, Sharon L.; Neikirk, Dean P.The corrosion of steel reinforcement in reinforced concrete structures constitutes an alarming problem. To combat this problem, researchers at the University of Texas at Austin developed two, low-cost, passive, wireless sensors: a threshold, corrosion sensor and an analog conductivity sensor. Today, the basic circuit designs for both sensors are finished and their reliabilities are confirmed. However, multiple problems regarding the durability of the sensors remain. This research project: (a) identifies these problems, (b) proposes enhancements for each type of passive, wireless sensor, (c) tests and evaluates the proposed modifications to the sensors, and (d) proposes potential improvements and areas of research regarding the future development of these two sensors.Item Passive inductively coupled wireless sensor for dielectric constant sensing(2013-05) Zhang, Sheng, active 2013; Neikirk, Dean P., 1957-In order to address the challenges of capacitive sensing in harsh environment, self resonant passive wireless sensors are studied. The capacitive sensing elements based on interdigitated capacitor (IDC) sensor are used. A semi-empirical model providing accurate capacitance calculation for IDCs over a wide range of dimensions and dielectric constants is developed. An equivalent circuit model based on electric field distribution is proposed, leading to a closed form approximation for IDC capacitance calculation. The conductivity of the material under test is also considered and a model is proposed to calculate effective capacitance as a function of conductivity and measurement frequency. The model is used to study the design optimization of IDC sensor and suggested design procedure is proposed. To wirelessly interrogate the capacitive sensor, it is connected to an inductive element to form a resonant circuit, while the measurement is made at remote reader coil. Advantages and disadvantages of different type of resonant structure design are analyzed. In order to assist the design process, a SPICE circuit model is developed to estimate the resonant frequency of the self resonant sensor. Miniaturized sensors with different dimensions are designed, fabricated and tested. The sensor is integrated with silicon nanowire fabric coated with polymer. Measurements are made to illustrate the enhancement in sensing capability by integrating chemical selective material.Item Structural Health Monitoring System utilizing Software Defined Radar Sensors to create a Wireless Smart Sensor Network.(2013-05) Rodriguez, Stephen; Li, Changzhi; Gale, Richard O.Structural Health Monitoring demands a multi sensor network that is not only cost effective and power controlled but also fists a small form factor. The system also needs to accurately detect low-frequency vibrations in civil infrastructure such as the Golden Gate Bridge. Existing systems are too expensive to transition to wireless space, costly to implement, or inaccurate. This thesis presents the use of a transponder to boost the return signal and prevent signal degradation over longer distances. The sensor can then be combined in a network by using an integrated ZigBee to form a sensor network similar to smart meters. A low cost processor will be integrated with the sensor to demodulate the signal accurately to measure cm, mm or smaller displacement of the structure. Experiments show that a multi radar sensor network can be used to monitor Structural Health.