81 research outputs found
Shear Piezoelectricity in Poly(vinylidenefluoride-co-trifluoroethylene): Full Piezotensor Coefficients by Molecular Modeling, Biaxial Transverse Response, and Use in Suspended Energy-Harvesting Nanostructures
No full textFerroelectric/piezoelectric flexible mechanical energy harvesters and stretchable epidermal sensors for medical applications
No full textMultifunctional sensing capability, ‘unusual’ formats with flexible/stretchable designs, rugged lightweight construction, and self-powered operation are desired attributes for electronics that directly interface with the human body. The collective results in this dissertation suggest utility in a variety of sensors and energy harvesting components, with lightweight construction, attractive mechanical properties and potential for implementation over large areas, with promising application in unusual bio-integrated electronics, such as self-powered cardiac pacemakers, skin-mounted blood pressure sensors, modulus sensors and skin cancer detection bio-patches. For these and related applications, unusual electronics provide the capability of intimate and conformal integration with a variety of substrates on biological tissues. These systems can be twisted, folded, stretched/flexed and wrapped onto curviliniar surfaces without damage or significant alteration in operation.
In this dissertation, the application of ferroelectric/piezoelectric materials and patterning techniques for ‘unusual’ electronics, with an emphasis on bio-integrated systems were demonstrated. Overall, the results suggest that the various sensor capabilities could be valuable for a range of applications in continuous self-powered health/wellness monitoring and clinical medicine.Item withdrawn by Mark Zulauf ([email protected]) on 2014-12-01T14:42:54Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 1
Dagdeviren_Canan.pdf: 13101093 bytes, checksum: 1ff904b8a9fc06cb3bd1aa2b12411180 (MD5)Made available in DSpace on 2015-01-21T19:59:05Z (GMT). No. of bitstreams: 1
Canan_Dagdeviren.pdf: 13104672 bytes, checksum: 9a9c9f9302f20ed63910187c4a195896 (MD5)Embargo set by: Seth Robbins for item 73257
Lift date: 2017-01-21T19:59:39Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 73257 on 2017-01-22T10:15:36Z
Cooperativity in the Enhanced Piezoelectric Response of Polymer Nanowires
No full textISSN:0935-9648ISSN:1521-4095ISSN:1521-409
Measured Output Voltages of Piezoelectric Devices Depend on the Resistance of Voltmeter
No full textPiezoelectric mechanical energy harvester (MEH) has been developed as an important emerging variant of piezoelectric devices. Experiments in the literature show that the voltage-time curves of piezoelectric devices encompass both positive and negative characteristics even though the strain in the piezoelectric material is always positive during the applied cycling load. This does not agree with the results predicted by the piezoelectric theory of open circuit. Here, both the experiments and theory are performed to understand this important problem. A zirconate titanate (PZT) MEH is fabricated and the output voltages are recorded with three voltmeters. It is found that the measured voltages depend on the resistance of voltmeter. The peak value of voltage increases with the increase of the resistance of voltmeter, which is contrary to the established knowledge that the measurement results are independent of the instruments used. A theoretical model considering the voltmeter with finite resistance is established. The charge is allowed to go through the voltmeter and switch the directions during increasing and releasing of strain. The results by this model agree well with those from the experiments. The findings suggest that the resistance of voltmeter should be reported for voltage measurement of the piezoelectric devices.Piezoelectric mechanical energy harvester (MEH) has been developed as an important emerging variant of piezoelectric devices. Experiments in the literature show that the voltage-time curves of piezoelectric devices encompass both positive and negative characteristics even though the strain in the piezoelectric material is always positive during the applied cycling load. This does not agree with the results predicted by the piezoelectric theory of open circuit. Here, both the experiments and theory are performed to understand this important problem. A zirconate titanate (PZT) MEH is fabricated and the output voltages are recorded with three voltmeters. It is found that the measured voltages depend on the resistance of voltmeter. The peak value of voltage increases with the increase of the resistance of voltmeter, which is contrary to the established knowledge that the measurement results are independent of the instruments used. A theoretical model considering the voltmeter with finite resistance is established. The charge is allowed to go through the voltmeter and switch the directions during increasing and releasing of strain. The results by this model agree well with those from the experiments. The findings suggest that the resistance of voltmeter should be reported for voltage measurement of the piezoelectric devices
An Emerging Era: Wearable Breast Ultrasonography at Home
No full textUltrasound is key for detecting breast cancer. However, current bulky, planar imaging devices do not fit the unique breast shape well. We have developed a new conformable Ultrasound Breast Patch (cUSBr-Patch), which overcomes this with a flexible transducer array, nature-inspired honeycomb patch, and accurate signal processing. This breakthrough allows breast ultrasound to become wearable, operator-independent, and more accessible
Towards device technologies non-invasive to our daily lives
No full textRecent advances in non-invasive technologies have shown disruptive potential for biomedical applications. However, while surgically non-invasive, they may introduce other types of limitations which interfere with the patient’s quality of life, from impracticalities and discomfort in daily life to social stigma
A conformable ultrasound patch for cavitation enhanced transdermal cosmeceutical delivery
No full textIncreased consumer interest in healthy-looking skin demands a safe and effective method to increase transdermal absorption of innovative therapeutic cosmeceuticals. However, permeation of small-molecule drugs is limited by the innate barrier function of the stratum corneum. Here, we report a conformable ultrasound patch (cUSP) that enhances transdermal transport of niacinamide by inducing intermediate-frequency sonophoresis in the fluid coupling medium between the patch and the skin. The cUSP consists of piezoelectric transducers embedded in a soft elastomer to create localized cavitation pockets (0.8 cm², 1 mm deep) over larger areas of conformal contact (20 cm²). Multiphysics simulation models, acoustic spectrum analysis and high-speed videography are used to characterize transducer deflection, acoustic pressure fields and resulting cavitation bubble dynamics in the coupling medium. The final system demonstrates a 26.2-fold enhancement in niacinamide transport in a porcine model in vitro with a 10-minute ultrasound application, demonstrating suitability of the device for short-exposure, large-area application of sonophoresis for patients and consumers suffering from skin conditions and premature skin aging.S.M
Microfabrication and characterization of a new box-shaped high frequency (7.5 MHz) low aperture 2D phased ultrasound transducer array
No full textMini electronics in wearables inspired this study. Thus, this work offers a new box-shaped high frequency (7.5 MHz) low aperture 2D phased sparse array ultrasonic transducer developed, built, and characterized. The capacity of matrix or 2D phased arrays to generate ultrasound beams without requiring any form of motion or mechanical steering holds potential value in the biomedical sonographic domain. However, these systems need a large number of piezoelectric elements to sample the active aperture, which is smaller than λ/2 wavelength between them, necessitating the need for a sizable or large transducer. To the best of knowledge, this is the first endeavor to design and microfabricate a 7.5 MHz transducer array, based on commercial PZT-5H polycrystalline materials, as tiny as 70x70 µm per transducer with a pitch of 102 µm to maintain an inter-element separation below 50% of the lambda. The study employs a square box-shaped structure that houses the transmitters and receivers perpendicular to each other, resulting in a reduced aperture and compact design compared to different commercial designs. This transducer not only provides satisfactory longitudinal k33 coefficient (0.45-0.5), acoustic pressure (2.1 kPa), sound pressure level (180 dB), low Q-factor (1.19), thermal stability, and high bandwidth (5.6 MHz, 73.41%), while minimizing cross-talk (<-50 dB), but also reduces the overall transducer area due to its unique sparse array configuration, resulting in a diminutive size (3.3 mm x 3.3 mm).S.M
Tailored multi-modal bodysuit for spatiotemporal physiological and physical activity monitoring
No full textThesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 92-98).The rapid advance of electronic devices and fabrication technologies have further promoted the field of wearables and smart textiles. Several challenges remain, as most of the current efforts in textile electronics focus on 'niche' applications and lack of sensing modalities, as well as large-scale coverage. We introduce a new platform of flexible-stretchable distributed sensor networks that can be embedded into a digitally-knit textile. It can be customized for various forms and functions using standard, accessible, and low-cost manufacturing approach. Rigorous experimental and theoretical investigations of each sensor modality, the robustness of sensor-interconnects system, washability, breathability, and sensor-to-skin contact pressure define the critical features of this novel electronic textile platform. The realization of a tailored, intelligent bodysuit that simultaneously and wirelessly monitors multi-nodal temperature, heart rate, and respiration, as well as physical activity demonstrates its vision for multi-functional, seamless health and activity monitoring, with potential implications in clinical medicine, healthcare, rehabilitation, and sports science.by Irmandy Wicaksono.S.M.S.M. Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Science
Automated Optimal Ultrasound Transducer Simulator
No full textOver the last couple of years, the demand for highly accurate, wearable, data capturing devices has been increasing. However, the prototyping process of ultrasound devices can be incredibly costly. In order to save time, many researchers run simulations in order to analyze the performance of their prototypes to help guide their manufacturing decisions. Unfortunately, many of these simulations need to be judged by a human and finding the best possible set of transducer specifications becomes increasingly difficult as the number of simulations grows. Currently there is no automated system for evaluating the performance of a simulated ultrasound array. This thesis proposes an automated system for generating ultrasound simulation images, feature extraction as well as a proposal for determining the best possible transducer configuration for the parameter that is being optimized. The results of an object oriented ultrasound simulation system and feature functions are demonstrated. The end goal will be to use the metric to more efficiently guide the fabrication decisions of the laboratory on current and future ultrasound projects.M.Eng
- …
