197 research outputs found
Growth inhibition induced by transforming growth factor-beta1 in human oral squamous cell carcinoma
No full textXiumei Wang, Wenjing Sun, Jing Bai, Linlin Ma, Yang Yu, Jingshu Geng, Jiping Qi, Zhongcheng Shi and Songbin F
Near-field wireless power transfer and communication system design for corneal intraocular prosthetic device
No full textThis thesis reports the design of a novel intraocular projection device for the treatment of intractable corneal opacity, with a design emphasis on the simultaneous wireless power and data transfer system. Electronic ocular prosthetics (EOP) or artificial eyes are devices designed to deliver artificial visual stimuli to patients with blindness to partially restore their visual function.
The need for wireless capabilities in EOPs arises from the highly limited physical space available for the intraocular implant devices. Early attempts at EOPs incorporated prohibitively large battery power sources and physical wire connections for the transmission of both power and information. However, one of the vital health regulations on medical implant devices involves the potential infection and inflammation caused by the implantation. Such regulations strictly prohibit the use of physical wire between the interbody and external-body components. This thesis presents a wireless power transfer (WPT) implementation that allows the battery to be kept outside of the patient’s body, significantly reducing the size of the implanted components, while still supplying energy to the implant without a signal exchange wire. The designed devices maintain the needed power and data exchange with the embedded parts while minimizing potential health complications from surgically inserted cables and bulky embedded hardware.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2020-12-01The student, Sarah Shim, accepted the attached license on 2018-12-02 at 14:14.The student, Sarah Shim, submitted this Thesis for approval on 2018-12-02 at 14:19.This Thesis was approved for publication on 2018-12-03 at 13:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #13174 on 2019-02-07 at 14:18:46Made available in DSpace on 2019-02-07T20:39:42Z (GMT). No. of bitstreams: 2
SHIM-THESIS-2018.pdf: 3418630 bytes, checksum: ff1ba62cc8186481f3d9dcc058ce740e (MD5)
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Previous issue date: 2018-12-03Embargo set by: Seth Robbins for item 109851
Lift date: 2021-02-07T20:39:46Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 109851
Lift date: 2021-02-07T20:44:35Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 109851 on 2021-02-08T10:15:18Z
Aluminum nitride microelectromechanical infrared detectors with integrated metamaterial absorbers
No full textThis work reports the development of uncooled spectrally selective mid-infrared (IR) detectors based on the seamless integration of metamaterial (MM) structures with microelectromechanical (MEMS) AlN resonators. Historically, uncooled absorbers have been limited in two key metrics: selectivity, the ability to distinguish distinct wavelengths of incident light, and sensitivity, the ability to detect low level amounts of radiation. In recent years, research has been done on improving these metrics using spectrally selective MM absorbers and highly sensitive MEMS detectors. In this thesis, the full hybridization of MM absorbers and MEMS resonators is demonstrated. The complete coverage of the resonator surface with both polarized and unpolarized MM results in high mid-IR absorption >80 % at an optimized spectral wavelength of 9.6 μm with a Full Width at Half Maximum (FWHM) of 1.02 μm without compromising resonator acoustic performance. A novel detector readout has also been implemented to boost sensitivity as well as to linearly convert incident IR power to a DC voltage for optimum integration into focal plane arrays (FPAs). A sensitivity metric called the temperature coefficient of reflection coefficient (TCΓ) is defined which is analogous to the temperature coefficient of resistance (TCR) described for conventional uncooled bolometer IR detectors. TCΓ values of 6% were measured, matching the state of the art TCR values of microbolometers which are typically 3-5%. Future optimization of device structure and fabrication can further increase the TCΓ value, showing promise for surpassing current microbolometer FPAs.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-08-01The student, Michael Breen, accepted the attached license on 2017-04-24 at 11:29.The student, Michael Breen, submitted this Thesis for approval on 2017-04-24 at 11:34.This Thesis was approved for publication on 2017-04-28 at 13:25.DSpace SAF Submission Ingestion Package generated from Vireo submission #11004 on 2017-09-29 at 10:45:26Made available in DSpace on 2017-09-29T17:45:19Z (GMT). No. of bitstreams: 2
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Previous issue date: 2017-04-28Embargo set by: Colleen Fallaw for item 103456
Lift date: 2019-09-29T17:48:06Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 103456
Lift date: 2020-03-02T19:56:41Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 103456
Lift date: 2020-03-02T19:59:52Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 103456
Lift date: 2020-03-02T20:02:46Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 103456 on 2020-03-03T10:15:11Z
Super-high-frequency lithium niobate microelectromechanical system resonators
No full textRecently, the rapid growth of super-high-frequency (SHF) applications has fueled the development of wideband filters and multiplexers. To achieve the desired performance, the building blocks of these filters, namely the acoustic resonators, must feature resonances at SHF, and high figure of merit (FOM) for minimal insertion loss and enhanced out-of-band rejection.
This thesis reports on the demonstration of a new class of SHF microelectromechanical system (MEMS) resonators operating in the 5 GHz range. The SHF resonances have been achieved by employing the first order antisymmetric (A1) mode in ion-sliced and suspended Z-cut lithium niobate (LiNbO3) thin films, which feature a phase velocity exceeding 10,000 m/s. The fabricated device has demonstrated a high electromechanical coupling (kt2) of 29% and a high quality factor (Q) of 527 simultaneously. Hence, this work marks the first time that MEMS resonators at SHF were demonstrated with an extremely high figure of merit (FoM= kt2Q) of 153. The SHF operation and high FoM of these A1 mode devices have proven their potential as the key building blocks for future SHF front-end filters and multiplexers.
This thesis is organized as follows. In Chapter 1, the background of RF-MEMS filters and resonators will be reviewed and the motivation of developing SHF MEMS resonators is clarified. Chapter 2 will introduce fundamentals and materials of piezoelectric MEMS resonators. Chapter 3 will discuss characteristics of Lamb wave modes and detail the first-order antisymmetric (A1) Lamb wave mode which can be employed in designs of SHF LiNbO3 MEMS resonators. Chapter 4 will present and describe the microfabrication process of the SHF LiNbO3 MEMS resonators. Finally, Chapter 5 will conclude this research work and suggest some potential future research directions.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2019-12-01The student, Yansong Yang, accepted the attached license on 2017-07-25 at 16:02.The student, Yansong Yang, submitted this Thesis for approval on 2017-07-25 at 16:03.This Thesis was approved for publication on 2017-07-26 at 16:39.DSpace SAF Submission Ingestion Package generated from Vireo submission #11583 on 2018-03-13 at 10:32:00Made available in DSpace on 2018-03-13T17:28:55Z (GMT). No. of bitstreams: 2
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Previous issue date: 2017-07-26Embargo set by: Seth Robbins for item 105413
Lift date: 2020-03-13T17:29:20Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 105413
Lift date: 2020-03-13T17:32:30Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 105413
Lift date: 2020-03-13T17:36:05Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 105413 on 2020-03-14T09:15:19Z
K-band lithium niobate microelectromechanical system hybrid filters
No full textAs the sub-6G spectrum becomes overcrowded with applications, the research community has begun to explore beyond 6 GHz for new spectral venues to advance wireless capabilities. Acoustic filters are indispensable front-end components in telecommunication, which is challenging to scale to higher frequencies. Frequency scaling without compromising performance remains challenging due to various technical bottlenecks in material integration, device fabrication, and filter design for acoustic filters.
This thesis presents the design approach as well as the first demonstration of a wideband hybrid monolithic acoustic filter in the K-band, which exceeds the limitation of electromechanical coupling on the fractional bandwidth (FBW) of acoustic filters. The hybrid filter utilizes the co-design of electromagnetic (EM) and acoustic to attain wide bandwidth while keeping the advantages of small size and high Q in the acoustic domain. The performance trade space and design flow of the hybrid filter are also presented in this thesis, which allows this technology to be applied for filters with different center frequencies and FBWs. The hybrid filter is simulated by hybridizing the EM and acoustic finite element analysis, which are carried out separately and combined at a system-level. The fabricated filter is built with the seventh-order antisymmetric Lamb wave mode (A7) resonators with an electromechanical coupling of 0.7%. The measurements show a 3 dB FBW of 2.4% at 19 GHz, and a compact footprint of 1.4 mm2.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-08-01The student, Liuqing Gao, accepted the attached license on 2020-07-16 at 10:19.The student, Liuqing Gao, submitted this Thesis for approval on 2020-07-16 at 10:28.This Thesis was approved for publication on 2020-07-20 at 09:18.DSpace SAF Submission Ingestion Package generated from Vireo submission #15652 on 2020-10-02 at 15:51:11Made available in DSpace on 2020-10-07T22:50:01Z (GMT). No. of bitstreams: 2
GAO-THESIS-2020.pdf: 2615417 bytes, checksum: b3d913f2f24b09b4c253a58d34a8d1ff (MD5)
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Previous issue date: 2020-07-20Embargo set by: Seth Robbins for item 116341
Lift date: 2022-10-07T22:50:13Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemAuthor requested closed access (OA after 2yrs) in Vireo ETD systemLimite
Near-field wireless power transfer to and communication with chip-scale devices
No full textSubmission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-08-01The student, Brandon Arakawa, accepted the attached license on 2017-07-19 at 15:34.The student, Brandon Arakawa, submitted this Thesis for approval on 2017-07-19 at 15:37.This Thesis was approved for publication on 2017-07-19 at 16:39.DSpace SAF Submission Ingestion Package generated from Vireo submission #11514 on 2018-03-02 at 13:02:31Made available in DSpace on 2018-03-02T19:59:45Z (GMT). No. of bitstreams: 2
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Previous issue date: 2017-07-19Embargo set by: Seth Robbins for item 105074
Lift date: 2020-03-02T19:59:52Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemThis thesis addresses the design challenges of achieving simultaneous near-field wireless power transfer to and communication with chip-scale devices that have a form factor on the order of 100s of microns and a thickness of 10s of microns. One application that requires this technology is the supply chain security for electronic components, in which a wireless chip-scale device is embedded within the package of a host electronic component in order to verify the provenance of the host as it passes through the supply chain. The need for wireless capabilities in such an application arises from the small form factor of the chip-scale device and its lack of space for a battery, while the authentication process for security assurance requires wireless data communication with the chip-scale device. Simultaneously achieving both capabilities involves the co-design of both the power and data transceivers with an optimized near-field coupling scheme.
The organization of the thesis is as follows. Chapter 2 covers electromagnetic coupling theory to achieve wireless power transfer. A tri-coil design approach is introduced to improve the wireless power transfer efficiency of the link compared to traditional two-coil designs. The design is verified using simulated and measured results. Additionally, a certain kind of circuit is required to enable a chip-scale device to support simultaneous power and communication. Chapter 3 presents a rectifier topology that achieves this purpose, and a prototype circuit is fabricated and measured to validate the design concepts. Finally, in order for a chip-scale device to be commercially viable, it needs to be compatible with standard CMOS fabrication processes. Chapter 4 discusses design strategies and procedures for multiple CMOS-compatible circuits for chip-scale simultaneous wireless power transfer and communication applications.Embargo set by: Seth Robbins for item 105074
Lift date: 2020-03-02T20:02:46Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 105074 on 2020-03-03T10:15:22Z
Design, fabrication, and characterization of lithium niobate whispering-gallery-mode microdisk and microring resonators and grating couplers
No full textLithium niobate (LiNbO3) is becoming popular in microelectronics and photonics research due to its exciting physical properties. Properties such as large electro-optic and piezoelectric coefficients make lithium niobate an excellent material for RF-photonics platforms that require center frequency tuning and large bandwidth for modulation. Photonic microresonators developed in LiNbO3 thin-films serve as the basic design unit of such platforms. This thesis provides preliminary characterizations of LiNbO3 whispering-gallery-mode microring and microdisk resonators, a single-ring filter, and grating couplers. The theory, simulation, fabrication, and experimental results of these devices are presented. Fabricated grating couplers with center wavelengths around 1560 nm are characterized and their insertion losses are explained. Microring and microdisk resonators with quality factors of 3-4 × 104 and a microring wavelength-dropping filter with a quality factor of 6.8 × 103 are demonstrated. Finally, the challenges in LiNbO3 micromachining and testing are discussed and future work for this research is suggested.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-05-01The student, Arunita Kar, accepted the attached license on 2018-04-17 at 15:27.The student, Arunita Kar, submitted this Thesis for approval on 2018-04-17 at 15:37.This Thesis was approved for publication on 2018-04-19 at 08:40.DSpace SAF Submission Ingestion Package generated from Vireo submission #12322 on 2018-08-31 at 17:29:32Made available in DSpace on 2018-09-04T20:47:20Z (GMT). No. of bitstreams: 3
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Previous issue date: 2018-04-19Embargo set by: Seth Robbins for item 107424
Lift date: 2020-09-04T20:47:38Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 107424
Lift date: 2020-09-04T20:50:11Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 107424 on 2020-09-05T09:15:26Z
Thin-Film Lithium Niobate Acoustic Delay Line Oscillators
No full textIn this work, thin-film lithium niobate (LiNbO3) acoustic delay line (ADL) based oscillators are experimentally investigated for the first time for the application of single-mode oscillators and frequency comb generation. The design space for the ADL-based oscillator is first analyzed, illustrating that the key to low phase noise lies in high center frequency (fo), large delay (τ G), and low insertion loss (IL) of the delay. Therefore, two self-sustained oscillators employing low noise amplifiers (LNA) and a low IL, long delay (fo=157MHz, IL =2.9dB, τG= 200-440ns) SH0 mode ADLs are designed for a case study. The two SH0 ADL oscillators show measured phase noise of -109 dBc/Hz and -127 dBc/Hz at 10-kHz offset while consuming 16 mA and 48 mA supply currents, respectively. Although the carrier power of the proposed oscillator is lower than published state-of-the-art ADL oscillators, competitive phase noise performance is still attained thanks to the low IL. Finally, frequency comb generation is also demonstrated with the same delay line and a commercial RF feedback amplifier, showing a comb spacing of 3.4 MHz that matches the open-loop characterization.Accepted Author ManuscriptDynamics of Micro and Nano System
Low-loss and wideband acoustic delay lines
No full text This paper demonstrates low-loss acoustic delay lines (ADLs) based on shear-horizontal waves in thin-film LiNbO 3 for the first time. Due to its high electromechanical coupling, the shear-horizontal mode is suited for producing devices with large bandwidths. Here, we show that shear-horizontal waves in LiNbO 3 thin films are also excellent for implementing low-loss ADLs based on unidirectional transducers. The high acoustic reflections and large transducer unidirectionality induced by the mechanical loading of the electrodes on a LiNbO 3 thin film provide a great tradeoff between delay line insertion loss and bandwidth. The directionality for two different types of unidirectional transducers has been characterized. Delay lines with variations in the key design parameters have been designed, fabricated, and measured. One of our fabricated devices has shown a group delay of 75 ns with an IL below 2 dB over a 3-dB bandwidth of 16 MHz centered at 160 MHz (fractional bandwidth = 10%). The measured insertion loss for other devices with longer delays and different numbers of transducer cells are analyzed, and the loss contributing factors and their possible mitigation are discussed. Accepted Author ManuscriptDynamics of Micro and Nano System
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