364 research outputs found
Impedance Spectroscopy
This book covers new advances in the field of impedance spectroscopy including fundamentals, methods and applications. It releases selected extended and peer reviewed scientific contributions from the International Workshop on Impedance Spectroscopy (IWIS 2017) focussing on detailed information about recent scientific research results in electrochemistry and battery research, bioimpedance measurement, sensors, system design, signal processing
Design and Validation of a Wearable, Continuous, and Non-Invasive Hydration Monitor that uses Ultrasonic Pulses to Detect Changes in Tissue Hydration Status
Chronic dehydration is an endemic problem for many population groups. Current methods of monitoring hydration status are invasive, time consuming, cannot be performed while exercising, and require lab resources. A proposed solution is a wearable, continuous, and non-invasive device that uses harm-free ultrasonic pulses to detect changes in tissue hydration status over time. Customer and engineering requirements were defined and used to guide the design process. Literature reviews were performed to identify essential information on dehydration, assess current methods, discover state of the art devices, and describe ultrasonic theory. Market research was performed to identify athletes as the target population group. An adjustable elastic nylon bicep band prototype was manufactured and the integration of more advanced components was proposed. The theoretical signal processing method used to detect hydration status was validated through initial tests with a prototype electrical system composed of a Teensy 3.1 board, two 18 kHz piezoceramic disc elements, and an Arduino/LabVIEW interface. Tests with aluminum, rubber, and sponge materials were performed to compare the signal response to propagation through materials with different acoustic properties and water contents. Finally, tests performed with dehydrated bovine muscle tissue revealed a statistically significant difference between hydrated and dehydrated tissue, a promising indication for future device refinement
Detection of breast cancer with electrical impedance mammography
Electrical Impedance Tomography (EIT) is a medical imaging technique that reconstructs internal electrical conductivity distribution of a body from impedance data that is measured on the body surface, and Electrical Impedance Mammography (EIM) is the technique that applies EIT in breast cancer detection. The use of EIM for breast cancer identification is highly desirable because it is a non-invasive and low-cost imaging technology. EIM has the potential in detecting early stage cancer, however there are still challenges that hindering EIM to be provided as a routine health care system. There are three major groups of obstacles. One is the hardware design, which includes the selection of electronic components, electrode-skin contacting methods, etc. Second is theoretical problems such as electrode configurations, image reconstruction and regularization methods. Third is the development of analysis methods and generation of a cancerous tissue database. Research reported in this thesis strives to understand these problems and aims to provide possible solutions to build a clinical EIM system.
The studies are carried out in four parts. First the functionalities of the Sussex Mk4 EIM system have been studied. Sensitivity of the system was investigated to find out the strength and weakness of the system. Then work has been made on image reconstruction and regularization methods in order to enhance the system’s endurance to noise, also to balance the reconstruction conductivity distribution throughout the reconstructed object. Then a novel cancer diagnosis technique was proposed. It was developed based on the electrical property of human breast tissue and the behaviour or systematic noise, to provide repeatable results for each patient. Finally evaluation has been made on previous EIM systems to find out the major problems. Based on sensitivity analysis, an optimal combined electrode configuration has been proposed to improve sensitivity.
The system has been developed and produced meaningful clinical images. The work makes significant contributions to society. This novel cancer diagnosis method has high accuracy for cancer identification. The combined electrode configuration has also provided flexibilities in the designing of current driving and voltage receiving patterns, thus sensitivity of the EIM system can be greatly improved
Firmware design of a portable medical device to measure the quadriceps muscle group after a total knee arthroplasty by EMG, LBIA and clinical score methods
El objetivo de este proyecto es el diseño del firmware de un dispositivo médico portátil para
mediciones de EMG y LBIA, que se utilizará para la evaluación de pacientes de artroplastia total de
rodilla, para estudiar la progresión de diferentes prótesis de rodilla (Medial-Pivot y Ultra-Congruente).
En la tesis, se expone el conocimiento actual de los estudios y aplicaciones de EMG y LBIA, junto con
los dispositivos comerciales utilizados actualmente. Además, se han estudiado e implementado las
diferentes técnicas de filtrado y procesamiento digital para señales de EMG y LBIAs. Adicionalmente,
se ha realizado un estudio estadístico preliminar con datos LBIA de 12 pacientes de artroplastia total
de rodilla.
El diseño del firmware de esta tesis incluye: los procesos de adquisición de datos con el uso de
diferentes ADCs (Conversor Analógico a Digital) (de la propia placa y externos, utilizando la interfaz SPI)
y un DAC (Conversor Digital a Analógico), el correspondiente procesamiento de la señal y la extracción
de sus características, la comunicación con un dispositivo externo utilizando un módulo BLE externo
con interfaz UART, el proceso de encriptación de los datos médicos, la funcionalidad de manejo de
errores y la aproximación del nivel de batería.
En esta tesis, todos los flujos de trabajo de los procesos se exponen y explican mediante diagramas de
flujo, mientras que se justifica cada cálculo y configuración. Además, todo el código correspondiente
se ha programado en lenguaje C y se expone en los anexos. También se ha revisado la normativa
aplicable y se ha analizado tanto el impacto ambiental como el coste económico del producto. Por
último, se proponen mejoras para futuros trabajos.The aim of this project is the firmware design for a portable medical device for EMG and LBIA
measurements which will be used for the assessment of total knee arthroplasty patients to study the
progression of different knee prostheses (Medial-Pivot and Ultra-Congruent). For its realization, the
state of the art of the EMG and LBIA studies and applications are exposed, along with the currently
used medical devices. In addition, the different digital filtering and processing techniques for these
studies have been studied and implemented. Furthermore, a preliminary statistical study has been
performed with LBIA data from 12 patients with total knee arthroplasty.
The firmware design of this thesis includes: the acquiring data processes with the use of different ADCs
(from the actual board and external, using the SPI interface) and a DAC, the corresponding signal
processing and feature abstraction, the communication with an external device using an external BLE
module with UART interface, the medical data encrypting process, the error handling functionality, and
the battery level approximation.
In this work, all the process workflows are exposed and explained using flowcharts, while every
calculation and configuration is justified. In addition, all the corresponding code has been programmed
using C language and exposed in the Annexes. Moreover, the applicable regulation has been reviewed,
and both the environmental impact and economic cost of the product have been analyzed. Finally,
improvements are proposed for future work.L'objectiu d'aquest projecte és el disseny del microprogramari d'un dispositiu mèdic portàtil per a
mesures d'EMG i LBIA. L’aparell mèdic s'utilitzarà per a l'avaluació de pacients d'artroplàstia total de
genoll per estudiar la progressió de dues pròtesis de genoll (Medial-Pivot i Ultra- Congruent). En el
treball, s'exposa el coneixement actual dels estudis i aplicacions d'EMG i LBIA, juntament amb els
dispositius comercials utilitzats actualment. A més, s'han estudiat i implementat les diferents tècniques
de filtrat i processament digital dels senyals de EMG i LBIA. Addicionalment, s'ha fet un estudi estadístic
preliminar amb dades de LBIA de 12 pacients amb artroplàstia total de genoll.
El disseny del microprogramari d'aquesta tesi inclou: els processos d'adquisició de dades fent ús de
diferents ADCs (de la pròpia placa i externs, utilitzant la interfície SPI) i un DAC, el processament dels
senyals i l'abstracció de les seves característiques, la comunicació amb un dispositiu extern utilitzant
un mòdul BLE extern amb interfície UART, el procés d'encriptació de les dades mèdiques, la
funcionalitat de l’avaluació d'errors i l'aproximació del nivell de bateria.
En aquest treball, totes les funcionalitats del dispositiu s'exposen i s'expliquen mitjançant diagrames
de flux i es justifiquen els càlculs i configuracions corresponents. Tot el codi desenvolupat s'ha
programat en llenguatge C i s'exposa als annexos. A més, s'ha revisat la normativa aplicable i s'ha
analitzat tant l'impacte ambiental com el cost econòmic de l’aparell. Finalment, es proposen millores
per a futurs desenvolupaments
Multi-frequency segmental bio-impedance device:design, development and applications
Bio-impedance analysis (BIA) provides a rapid, non-invasive technique for body composition estimation. BIA offers a convenient alternative to standard techniques such as MRI, CT scan or DEXA scan for selected types of body composition analysis. The accuracy of BIA is limited because it is an indirect method of composition analysis. It relies on linear relationships between measured impedance and morphological parameters such as height and weight to derive estimates. To overcome these underlying limitations of BIA, a multi-frequency segmental bio-impedance device was constructed through a series of iterative enhancements and improvements of existing BIA instrumentation. Key features of the design included an easy to construct current-source and compact PCB design. The final device was trialled with 22 human volunteers and measured impedance was compared against body composition estimates obtained by DEXA scan. This enabled the development of newer techniques to make BIA predictions. To add a ‘visual aspect’ to BIA, volunteers were scanned in 3D using an inexpensive scattered light gadget (Xbox Kinect controller) and 3D volumes of their limbs were compared with BIA measurements to further improve BIA predictions. A three-stage digital filtering scheme was also implemented to enable extraction of heart-rate data from recorded bio-electrical signals. Additionally modifications have been introduced to measure change in bio-impedance with motion, this could be adapted to further improve accuracy and veracity for limb composition analysis. The findings in this thesis aim to give new direction to the prediction of body composition using BIA. The design development and refinement applied to BIA in this research programme suggest new opportunities to enhance the accuracy and clinical utility of BIA for the prediction of body composition analysis. In particular, the use of bio-impedance to predict limb volumes which would provide an additional metric for body composition measurement and help distinguish between fat and muscle content
Impedance Sensing of Cancer Cells Directly on Sensory Bioscaffolds of Bioceramics Nanofibers
Cancer cell research has been growing for decades. In the field of cancer pathology, there is an increasing and long-unmet need to develop a new technology for low-cost, rapid, sensitive, selective, label-free (i.e. direct), simple and reliable screening, diagnosis, and monitoring of live cancer and normal cells in same shape and size from the same anatomic region. For the first time on using an impedance signal, the breast cancer and normal cells have been thus screened, diagnosed and monitored on a smart bioscaffold of entangled nanowires of bioceramics titanate grown directly on the surface of implantable Ti-metal and characterized by SEM, XRD, etc. following a technology patented by Tian-lab. In experiment in the aqueous solution of phosphate buffer saline (PBS), human breast benign (MCF7) and aggressive (MDA-MB231) cancer cells, normal (MCF10A) cells, and colon cancer cells (HCT116) showed characteristic impedance spectrum highly different than that of the blank sensor (i.e. no cells on the bioscaffold surface). For two sets of mixtures each containing the normal and cancer cells over a wide range of mixing ratios, the shift of impedance signals has been linearly correlated with the mixing ratios which supports the biosensor’s selectivity and reliability. After being treated with pure glucose and chemotherapeutic drug (i.e. doxorubicin of DOX) and with one after the other, the breast cancer cells showed different impedance signals corresponding to their difference in glucose metabolisms (i.e. Warburg Effect) and resistances to the Dox, thus-fingerprinting the cells easily. Based on the nanostructure chemistry, impedance equivalent circuitry and cancer cell biology, it’s the different cells surface binding on the nanowires, and different cancer cells metabolic wastes from the different treatments on the nanowires that changed the charge density on the scaffolding nanowire surface and in turn changed the impedance signals. This new method is believed expandable to quantifying and characterizing live cells and even biological tissues of different types in general
Design, modelling and fabrication of micro-scale electrode arrays (MEAs) for micro-bioimpedance tomography
This research involves the design and fabrication of micro-scale electrodes and optimisation
of image reconstruction techniques. It aims to explore the use of bioimpedance
tomography techniques in extracting some structured information on three-dimensional
(3D) cell growth for the purpose of identifying cancer development, such as, cancer cell
spheroids. Electrical impedance tomography (EIT) is a non-invasive imaging technique
that maps the variation in conductivity of a sample, in the form of two or three dimensions.
This technique has been successfully used in many clinical applications, for
example, in detection of breast cancer, acute stroke differentiation, detection of bleeding
due to traumatic brain injury, and detection of bacterial infection during surgery.
The capability of EIT to spatially map biological development process enables it to
be used in monitoring cell growth in three-dimensional formation. The work presented
in this thesis includes miniaturising the electrode designs from a millimetre-scale on
a PCB to a micrometre-scale on a glass substrate, and on a flexible material. Apart
from the fabrication and experimental work, sensitivity analysis was performed using
COMSOL Multiphysics® modelling. The final electrode design, the flexible micro-scale
electrode array (Flex-MEA), is fabricated on a flexible printed circuit board (PCB).
The development of Flex-MEA technology with improved imaging reconstruction on
micro-scale has produced an improved high-throughput and showed great potential as
a research aid in drug discovery. The research has proven that Flex-MEA enables improved
electrode arrangement compared with planar Pt electrodes making it a superior
choice as a portable, non-invasive technique to image the growth of microbial cultures.
Successful measurements of cell growth and proliferation propounded by this research
will have a definite potential not only in the biomedical field, example, in therapeutic
drug monitoring, but also in bioprocessing technology
Design, characterization and validation of integrated bioelectronics for cellular studies: from inkjet-printed sensors to organic actuators
Mención Internacional en el título de doctorAdvances in bioinspired and biomimetic electronics have enabled
coupling engineering devices to biological systems with unprecedented
integration levels. Major efforts, however, have been devoted to interface
malleable electronic devices externally to the organs and tissues. A promising
alternative is embedding electronics into living tissues/organs or,
turning the concept inside out, lading electronic devices with soft living
matters which may accomplish remote monitoring and control of tissue’s
functions from within. This endeavor may unleash the ability to engineer
“living electronics” for regenerative medicine and biomedical applications.
In this context, it remains a challenge to insert electronic devices efficiently
with living cells in a way that there are minimal adverse reactions
in the biological host while the electronics maintaining the engineered
functionalities. In addition, investigating in real-time and with minimal
invasion the long-term responses of biological systems that are brought
in contact with such bioelectronic devices is desirable.
In this work we introduce the development (design, fabrication and
characterization) and validation of sensors and actuators mechanically
soft and compliant to cells able to properly operate embedded into a
cell culture environment, specifically of a cell line of human epithelial
keratinocytes. For the development of the sensors we propose moving from conventional microtechnology approaches to techniques compatible
with bioprinting in a way to support the eventual fabrication of tissues
and electronic sensors in a single hybrid plataform simultaneously. For
the actuators we explore the use of electroactive, organic, printing-compatible
polymers to induce cellular responses as a drug-free alternative
to the classic chemical route in a way to gain eventual control of biological
behaviors electronically. In particular, the presented work introduces
inkjet-printed interdigitated electrodes to monitor label-freely and
non-invasively cellular migration, proliferation and cell-sensor adhesions
of epidermal cells (HaCaT cells) using impedance spectroscopy and the
effects of (dynamic) mechanical stimulation on proliferation, migration
and morphology of keratinocytes by varying the magnitude, frequency
and duration of mechanical stimuli exploiting the developed biocompatible
actuator.
The results of this thesis contribute to the envision of three-dimensional
laboratory-growth tissues with built-in electronics, paving exciting
avenues towards the idea of living smart cyborg-skin substitutes.En los útimos años los avances en el desarrollo de dispositivos
electrónicos diseñados imitando las propiedades de sistemas vivos han
logrado acoplar sistemas electrónicos y órganos/tejidos biológicos con
un nivel de integración sin precedentes. Convencionalmente, la forma
en que estos sistemas bioelectrónicos son integrados con órganos o tejidos
ha sido a través del contacto superficial entre ambos sistemas, es
decir acoplando la electrónica externamente al tejido. Lamentablemente
estas aproximaciones no contemplan escenarios donde ha habido una
pérdida o daño del tejido con el cual interactuar, como es el caso de daños
en la piel debido a quemaduras, úlceras u otras lesiones genéticas
o producidas. Una alternativa prometedora para ingeniería de tejidos y
medicina regenerativa, y en particular para implantes de piel, es embeber
la electrónica dentro del tejido, o presentado de otra manera, cargar
el sistema electrónico con células vivas y tejidos fabricados por ingeniería
de tejidos como parte innata del propio dispositivo. Este concepto
permitiría no solo una monitorización remota y un control basado en
señalizaciones eléctricas (sin químicos) de tejidos biológicos fabricados
mediante técnicas de bioingeniería desde dentro del propio tejido, sino
también la fabricación de una “electrónica viva”, biológica y eléctricamente
funcional. En este contexto, es un desafío insertar de manera
eficiente dispositivos electrónicos con células vivas sin desencadenar
reacciones adversas en el sistema biológico receptor ni en el sistema
electrónico diseñado. Además, es deseable monitorizar en tiempo real
y de manera mínimamente invasiva las respuestas de dichos sistemas
biológicos que se han añadido a tales dispositivos bioelectrónicos.
En este trabajo presentamos el desarrollo (diseño, fabricación y caracterización)
y validación de sensores y actuadores mecánicamente suaves y
compatibles con células capaces de funcionar correctamente dentro de un
entorno de cultivo celular, específicamente de una línea celular de células epiteliales
humanas. Para el desarrollo de los sensores hemos propuesto utilizar
técnicas compatibles con la bioimpresión, alejándonos de la micro fabricación
tradicionalmente usada para la manufactura de sensores electrónicos, con el
objetivo a largo plazo de promover la fabricación de los tejidos y los sensores
electrónicos simultáneamente en un mismo sistema de impresión híbrido.
Para el desarrollo de los actuadores hemos explorado el uso de polímeros
electroactivos y compatibles con impresión y hemos investigado el efecto
de estímulos mecánicos dinámicos en respuestas celulares con el objetivo a
largo plazo de autoinducir comportamientos biológicos controlados de forma
electrónica. En concreto, este trabajo presenta sensores basados en electrodos
interdigitados impresos por inyección de tinta para monitorear la migración
celular, proliferación y adhesiones célula-sustrato de una línea celular de
células epiteliales humanas (HaCaT) en tiempo real y de manera no invasiva
mediante espectroscopía de impedancia. Por otro lado, este trabajo presenta
actuadores biocompatibles basados en el polímero piezoeléctrico fluoruro de
poli vinilideno y ha investigado los efectos de estimular mecánicamente células
epiteliales en relación con la proliferación, migración y morfología celular
mediante variaciones dinámicas de la magnitud, frecuencia y duración de
estímulos mecánicos explotando el actuador biocompatible propuesto.
Ambos sistemas presentados como resultado de esta tesis doctoral
contribuyen al desarrollo de tejidos 3D con electrónica incorporada,
promoviendo una investigación hacia la fabricación de sustitutos equivalentes
de piel mitad orgánica mitad electrónica como tejidos funcionales
biónicos inteligentes.The main works presented in this thesis have been
conducted in the facilities of the Universidad Carlos III
de Madrid with support from the program Formación del
Profesorado Universitario FPU015/06208 granted by Spanish Ministry
of Education, Culture and Sports. Some of the work has been also
developed in the facilities of the Fraunhofer-Institut für Zuverlässigkeit
und Mikrointegration (IZM) and University of Applied Sciences (HTW) in
Berlin, under the supervision of Prof. Dr. Ing. H-D. Ngo during a research
visit funded by the Mobility Fellows Program by the Spanish Ministry of
Education, Culture, and Sports.
This work has been developed in the framework of the projects
BIOPIELTEC-CM (P2018/BAA-4480), funded by Comunidad de Madrid,
and PARAQUA (TEC2017-86271-R) funded by Ministerio de Ciencia e
Innovación.Programa de Doctorado en Ingeniería Eléctrica, Electrónica y Automática por la Universidad Carlos III de MadridPresidente: José Antonio García Souto.- Secretario: Carlos Elvira Pujalte.- Vocal: María Dimak
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