A ZigBee-based wireless biomedical sensor network as a precursor to an in-suit system for monitoring astronaut state of health

Master of ScienceDepartment of Electrical and Computer EngineeringSteven WarrenNetworks of low-power, in-suit, wired and wireless health sensors offer the potential to track and predict the health of astronauts engaged in extra-vehicular and in-station activities in zero- or reduced- gravity environments. Fundamental research questions exist regarding (a) types and form factors of biomedical sensors best suited for these applications, (b) optimal ways to render wired/wireless on-body networks with the objective to draw little-to-no power, and (c) means to address the wireless transmission challenges offered by a spacesuit constructed from layers of aluminized mylar. This thesis addresses elements of these research questions through the implementation of a collection of ZigBee-based wireless health monitoring devices that can potentially be integrated into a spacesuit, thereby providing continuous information regarding astronaut fatigue and state of health. Wearable biomedical devices investigated for this effort include electrocardiographs, electromyographs, pulse oximeters, inductive plethysmographs, and accelerometers/gyrometers. These ZigBee-enabled sensors will form the nodes of an in-suit ZigBee Pro network that will be used to (1) establish throughput requirements for a functional in-suit network and (2) serve as a performance baseline for future devices that employ ultra-low-power field-programmable gate arrays and micro-transceivers. Sensor devices will upload data to a ZigBee network coordinator that has the form of a pluggable USB connector. Data are currently visualized using MATLAB and LabVIEW

Sensor de fotopletismografia por reflexão sem fios: projeto e desenvolvimento de hardware

Nos anos oitenta do último século começaram a surguir oxímetros wearable que se estabeleceram como um standart para a monitorização da saturação de oxigénio no sangue e actividade cardíaca, de forma não intrusiva. Os referidos oxímetros medem a percentagem de hemoglobina totalmente saturada com oxigénio (SPO2), transmitindo luz com comprimentos de onda diferentes, vermelha e infra-vermelha, através dos tecidos. Os dispositivos wearable atuais são frequentemente desenhados de forma modular, em que o módulo de medição e de display são integrados num único dispositivo. O armazenamento e tratamento de dados é difícil uma vez que são dispositivos de tamanho reduzido; baixo consumo de energia; baixo custo e baixa capacidade de processamento de dados. Tendo em conta que a quantidade de dados recolhidos é relativamente baixa, a sua transmissão de forma wireless é conveniente. Nesta dissertação é desenvolvido e testado um oxímetro de pulso em modo refletivo capaz de cálcular a saturação de oxigénio no sangue, o batimento cardíaco e enviar os dados de forma wireless para outros dispositivos. O hardware desenvolvido engloba quatro módulos funcionais: fonte de alimentação constituída por um conversor DC-DC e um regulador de tensão linear, circuito de carga e monitorização da bateria que controla os ciclos de carga e descarga da bateria, um módulo de rádio frequência que permite que o oxímetro comunique com outros dispositivos de forma wireless e um microcontrolador responsável por gerir todas as comunicações e pelo processamento de sinal. O sofware desenvolvido divide-se em duas partes: uma interface gráfica escrita em Matlab que permite a comunicação entre o computador e o oxímetro e o firmware do microcontrolador que engloba todos os algoritmos de cálculo do SPO2, do batimento cardíaco, drivers de periféricos, gestão das comunicações e aquisição e processamento dos dados.Ever since the early 80s from the last century, wearable oximeters appear as the established standard for non-invasive monitoring of arterial oxygen saturation (SpO2) and heart activity wearable oximeters can monitor arterial SpO2, which is the percentage of arterial hemoglobin that is fully saturated with oxygen, by transmitting red and infrared light through the finger, where it is sensed. The current wearable oximeters are frequently designed as single modular devices, namely, the measurement and display modules are integrated on a single device, which are responsible for several problems. Such devices lack effective data management functions and by being limited by size, power consumption and cost, advanced operating systems cannot be embedded to such wearable oximeters, making difficult to store and manage data. Bearing in mind that the amount of data pulse wave signal collected is small, transmit it wirelessly is convenient and effective. In this thesis a reflective pulse oximeter is developed and tested capable of assessing the oxygen blood saturation (SpO2), the heart rate and send the acquired data through wireless communication to other devices. The developed hardware comprises four functional modules: the power supply made of a DCDC converter and a linear voltage regulator, the charging circuit and battery monitoring system which controls the charging and discharging cycles of the battery, a radio-frequency module that allows the device to connect through wireless communication to other devices and a microcontroller responsible for the management of the communications and for the signal processing. The software developed in this thesis is made of two parts. One being the Matlab graphical interface that allows the communication between the oximeter and the PC while the other one being the microcontroller which comprises all the algorithms of SpO2, heart rate, management of the communication, drivers, and data acquisition and processing

Chest Wearable Apparatus for Cuffless Continuous Blood Pressure Measurements Based on PPG and PCG Signals

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