Microfabricated Implantable Parylene-Based Wireless Passive Intraocular Pressure Sensors

This paper presents an implantable parylene-based wireless pressure sensor for biomedical pressure sensing applications specifically designed for continuous intraocular pressure (IOP) monitoring in glaucoma patients. It has an electrical LC tank resonant circuit formed by an integrated capacitor and an inductor coil to facilitate passive wireless sensing using an external interrogating coil connected to a readout unit. Two surface-micromachined sensor designs incorporating variable capacitor and variable capacitor/inductor resonant circuits have been implemented to realize the pressure-sensitive components. The sensor is monolithically microfabricated by exploiting parylene as a biocompatible structural material in a suitable form factor for minimally invasive intraocular implantation. Pressure responses of the microsensor have been characterized to demonstrate its high pressure sensitivity (> 7000 ppm/mmHg) in both sensor designs, which confirms the feasibility of pressure sensing with smaller than 1 mmHg of resolution for practical biomedical applications. A six-month animal study verifies the in vivo bioefficacy and biostability of the implant in the intraocular environment with no surgical or postoperative complications. Preliminary ex vivo experimental results verify the IOP sensing feasibility of such device. This sensor will ultimately be implanted at the pars plana or on the iris of the eye to fulfill continuous, convenient, direct, and faithful IOP monitoring

Overview of sensors suitable for active flow control methods

Hlavným cieľom tejto bakalárskej práce bolo vytvorenie prehľadu vyvíjaných a už aplikovaných senzorov pre účely aktívneho riadenia prúdov. Senzory musia splňovať niektoré podmienky, preto výber senzorov bol naviazaný na reálnych výsledkoch testovacích programov, popis ktorých tvorí prvú časť tejto bakalárskej práce. Opis technológie a princíp fungovania senzorov je popísaný v druhej časti tejto práce.The main purpose of this bachelor thesis was to create the overview of the sensors developed for the future active flow control applications and overview the sensors already used in the active flow control applications. The sensors have to fulfil several requirements, so selection for the overview was based on the real flight test programs results, which were described in the first part of the thesis. The sensors technology description and operation principles were included in the second part of the thesis

Developing a joint-on-chip platform:A multi-organ-on-chip model to mimic healthy and diseased conditions of the synovial joints

Arthritis affects millions of people worldwide. With only a few disease-modifying drugs available for treatment of rheumatoid arthritis and none for osteoarthritis, a clear need exists for new treatment options. Current disease models used for drug screening and development suffer from several disadvantages and most importantly, do not accurately emulate all facets of human joint diseases. A humanized joint-on-chip (JoC) model or platform could revolutionize research and drug development in rheumatic diseases. A JoC model is a multi-organ-on-chip platform that incorporates a range of engineered features to emulate essential aspects and functions of the human joint and faithfully recapitulates the joint’s physiological responses. In this thesis we propose an architecture of such JoC platform. Furthermore, we present a cartilage-on-chip and a synovial membrane-on-chip models which function as a minimal functional unit for drug screening and biomarker investigation. The first model incorporates a mechanical actuation unit to emulate the forces exerted onto the cartilage during movement and shows promising results in terms of matrix maturation and cell differentiation. The synovial membrane model incorporates the immune system, an essential component in disease development. Here, by adding inflammatory cytokines it is possible to trigger an inflammation similar to arthritic diseases. The end goal is to obtain a reliable and ready-to-use humanized model of the joint for studying the pathophysiology of rheumatic diseases and screening drugs for treatment of these conditions

Construction and commissioning of a technological prototype of a high-granularity semi-digital hadronic calorimeter

A large prototype of 1.3m3 was designed and built as a demonstrator of the semi-digital hadronic calorimeter (SDHCAL) concept proposed for the future ILC experiments. The prototype is a sampling hadronic calorimeter of 48 units. Each unit is built of an active layer made of 1m2 Glass Resistive Plate Chamber(GRPC) detector placed inside a cassette whose walls are made of stainless steel. The cassette contains also the electronics used to read out the GRPC detector. The lateral granularity of the active layer is provided by the electronics pick-up pads of 1cm2 each. The cassettes are inserted into a self-supporting mechanical structure built also of stainless steel plates which, with the cassettes walls, play the role of the absorber. The prototype was designed to be very compact and important efforts were made to minimize the number of services cables to optimize the efficiency of the Particle Flow Algorithm techniques to be used in the future ILC experiments. The different components of the SDHCAL prototype were studied individually and strict criteria were applied for the final selection of these components. Basic calibration procedures were performed after the prototype assembling. The prototype is the first of a series of new-generation detectors equipped with a power-pulsing mode intended to reduce the power consumption of this highly granular detector. A dedicated acquisition system was developed to deal with the output of more than 440000 electronics channels in both trigger and triggerless modes. After its completion in 2011, the prototype was commissioned using cosmic rays and particles beams at CERN.Comment: 49 pages, 41 figure

Development of an Integrated Microfluidic Perfusion Cell Culture System for Real-Time Microscopic Observation of Biological Cells

This study reports an integrated microfluidic perfusion cell culture system consisting of a microfluidic cell culture chip, and an indium tin oxide (ITO) glass-based microheater chip for micro-scale perfusion cell culture, and its real-time microscopic observation. The system features in maintaining both uniform, and stable chemical or thermal environments, and providing a backflow-free medium pumping, and a precise thermal control functions. In this work, the performance of the medium pumping scheme, and the ITO glass microheater were experimentally evaluated. Results show that the medium delivery mechanism was able to provide pumping rates ranging from 15.4 to 120.0 μL·min−1. In addition, numerical simulation and experimental evaluation were conducted to verify that the ITO glass microheater was capable of providing a spatially uniform thermal environment, and precise temperature control with a mild variation of ±0.3 °C. Furthermore, a perfusion cell culture was successfully demonstrated, showing the cultured cells were kept at high cell viability of 95 ± 2%. In the process, the cultured chondrocytes can be clearly visualized microscopically. As a whole, the proposed cell culture system has paved an alternative route to carry out real-time microscopic observation of biological cells in a simple, user-friendly, and low cost manner

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

Modular integration and on-chip sensing approaches for tunable fluid control polymer microdevices

228 p.Doktore tesi honetan mikroemariak kontrolatzeko elementuak diseinatu eta garatuko dira, mikrobalbula eta mikrosentsore bat zehazki. Ondoren, gailu horiek batera integratuko dira likido emari kontrolatzaile bat sortzeko asmotan. Helburu nagusia gailuen fabrikazio arkitektura modular bat frogatzea da, non Lab-on-a-Chip prototipoak garatzeko beharrezko fase guztiak harmonizatuz, Cyclic-Olefin-Polymer termoplastikozko mikrogailu merkeak pausu gutxi batzuetan garatuko diren, hauen kalitate industriala bermatuz. Ildo horretan, mikrogailuak prototipotik produkturako trantsizio azkar, erraz, errentagarri eta arriskurik gabeen bidez lortu daitezkeenetz frogatuko da

Design and evaluation of an instrumented microfluidic organotypic device and sensor module for organ-on-a-chip applications

2020 Summer.Includes bibliographical references.Organ and tissue-on-a-chip technologies are powerful tools for drug discovery and disease modeling, yet many of these systems rely heavily on in vitro cell culture to create reductionist models of tissues and organs. Therefore, Organ-on-chip devices recapitulate some tissue functions and are useful for high-throughput screening but fail to capture the richness of cellular interactions of tissues in vivo because they lack the cellular diversity and complex architecture of native tissue. This thesis describes the design and testing of 1) a microfluidic organotypic device (MOD) for culture of murine intestinal tissue and 2) a microfluidic sensor module to be implemented inline with the MOD for real-time sensing of analytes and metabolites. The MOD houses full-thickness murine intestinal tissue, including muscular, neural, immune, and epithelial components. We used the MOD system to maintain murine intestinal explants for 72 h ex vivo. Explants cultured in the MOD formed a barrier between independent fluidic channels perfused with media, which is critical to recapitulating intestinal barrier function in vivo. We also established differential oxygen concentrations in the fluidic channels and showed that more bacteria were present on the tissue's mucosal surface when exposed to near-anoxic media. The sensor module is a reversibly sealed microfluidic device with magnetic connections that can withstand high backpressures. Further, electrodes housed in commercial finger-tight fittings were integrated into the sensor module in a plug-and-play format. Future work will include developing electrochemical/optical sensors for various biological compounds relevant to intestinal physiology. Ultimately, the MOD and sensor module will be implemented in long-term microbiome studies to elucidate the relationship among microbial, epithelial, neuro and immune components of the gut wall in health and disease

Thin Film Based Biocompatible Sensors for Physiological Monitoring

The development and evolution of physiological sensors, from wearable to implantable, has enabled long term continuous physiological monitoring, making possible for the out-of-clinic treatment and management of many chronic illnesses, mental health issues and post-surgery recovery. This technology advance is gradually changing the definition of health care and the way it is delivered, from clinic/emergency room to patient’s own environment. In this dissertation, three general types of sensors have been proposed for physiological monitoring of blood pressure, oxygen content and electrolyte ion concentration level in human body, respectively. The study proved the device concepts and shows promising results with the prototype sensors for possibilities of various biomedical applications. In the pressure sensor development, we have designed, fabricated and characterized a biocompatible, flexible pressure sensor using Au thin film patterned polydimethylsiloxane (PDMS) membrane for bio-implant application. Strain induced changes in Au film resistance was used to perform quantitative measurement of absolute pressure. The sensor was extensively modeled through COMSOL-based finite element simulations for design and performance predication. Three prototype sensors fabricated with different membrane thickness of 50, 100 and 200 μm were studied. Very high constant sensitivities of 0.1 /Kpa, 0.056 /Kpa and 0.012 /Kpa, respectively, were observed over their effective measurement ranges. The high sensitivities are attributed to the formation of microcracks in Au film resistor when the sensors are subjected to pressure. Interestingly, the formation of microcracks seemed to be quite reversible within certain pressure range. In addition, the correlation of sensitivity and effective sensing range with membrane thickness was studied for the three sensors. It was found that the device sensitivity increased with the decrease in membrane thickness but at the expense of its effective sensing range. This observation corresponds well to the simulation results. Response times of all the three sensors were found to be in millisecond range, and the best rms noise limited resolution was 0.07 mmHg (9 Pa). In the oxygen sensor development, oxygen sensing characteristics of In2O3 thin film at room temperature have been investigated through conductivity measurements using interdigitated metal finger patterned devices. We observed that the O2 sensitivity gets affected very significantly in presence of moisture, as well as with applied dc bias. The O2 sensitivity was found to increase several times in moist ambient compared to dry ambient condition. Higher dc bias also dramatically improved the sensitivity, which varied more than two orders of magnitude as the dc bias was increased from 0.5 to 10 V. We propose that the observed increase in sensitivity in presence of moisture is caused by enhanced surface electron density on In2O3 thin film resulting from the donation of electrons by the chemisorbed water molecules. The adsorption of O2 molecules, which subsequently formed O2- ions, leads to chemical gating of the sensor devices, which under larger dc bias produced a higher fractional change in current leading to higher sensitivity. In the development of biocompatible ion sensor, a novel ion sensitive field effect transistor (ISFET), fabricated using chemical vapor deposition (CVD) derived graphene, has been proposed and demonstrated for real-time K+ efflux measurement from living cells. Ion concentration change in electrolyte solution is transduced into an electrical (current) signal due to surface potential change in graphene (the material constructing the electrical conducting channel of the ISFET). Graphene, a two-dimensional carbon allotrope recently discovered in 2004, has a number of exceptional material properties which is much superior to silicon with respect to developing sensors for bio-detection applications, such as its ultra-high carrier mobility, excellent biocompatibility and very good chemical stability. In this work, we have extensively studied the I-V and C-V characteristics of the graphene ISFET in both electrolyte and physical buffer solutions with different K+ concentration. Valinomycin coating of the graphene ISFETs has been utilized to enhance ionic detection sensitivity and impart selectivity. With the ionophore modified graphene ISFET, we have successfully demonstrated real-time detection of K+ concentration change in both electrolyte and physiological buffer solutions. Moreover, we have conducted cell based real-time K+ efflux measurement utilizing commercial Si based ISFETs, proving the concept of ISFET based ion channel screening assay for drug discovery. On the other hand, the prototype graphene based ISFET has also been evaluated for K+ efflux detection using a salt bridge configuration, showing promising sensing results for future study. In the fabrication of graphene ISFET, we found the epoxy glue used for the sensor encapsulation had significant effect on the electric transport properties of graphene including conductivity, carrier concentration and field effect mobility. N-type doping effect of the epoxy on graphene has been carefully identified and confirmed by systematic experiments, which is promising for new alternative approach to dope graphene