Flexible Sensor for Wearable Vital Sign Monitoring System

In modern society, the body health is a very important issue to everyone. With the development of the science and technology, the new and developed body health monitoring device and technology will play the key role in the daily medical activities. This paper focus on making progress in the design of the wearable vital sign system. A vital sign monitoring system has been proposed and designed. The whole detection system is composed of signal collecting subsystem, signal processing subsystem, short-range wireless communication subsystem and user interface subsystem. The signal collecting subsystem is composed of light source and photo diode, after emiting light of two different wavelength, the photo diode collects the light signal reflected by human body tissue. The signal processing subsystem is based on the analog front end AFE4490 and peripheral circuits, the collected analog signal would be filtered and converted into digital signal in this stage. After a series of processing, the signal would be transmitted to the short-range wireless communication subsystem through SPI, this subsystem is mainly based on Bluetooth 4.0 protocol and ultra-low power System on Chip(SoC) nRF51822. Finally, the signal would be transmitted to the user end. After proposing and building the system, this paper focus on the research of the key component in the system, that is, the photo detector. Based on the study of the perovskite materials, a low temperature processed photo detector has been proposed, designed and researched. The device is made up of light absorbing layer, electron transporting and hole blocking layer, hole transporting and electron blocking layer, conductive substrate layer and metal electrode layer. The light absorbing layer is the important part of whole device, and it is fabricated by perovskite materials. After accepting the light, the electron-hole pair would be produced in this layer, and due to the energy level difference, the electron and hole produced would be transmitted to metal electrode and conductive substrate electrode through electron transporting layer and hole transporting layer respectively. In this way the response current would be produced. Based on this structure, the specific fabrication procedure including substrate cleaning; PEDOT:PSS layer preparation; pervoskite layer preparation; PCBM layer preparation; C60, BCP, and Ag electrode layer preparation. After the device fabrication, a series of morphological characterization and performance testing has been done. The testing procedure including film-forming quality inspection, response current and light wavelength analysis, linearity and response time and other optical and electrical properties testing. The testing result shows that the membrane has been fabricated uniformly; the device can produce obvious response current to the incident light with the wavelength from 350nm to 800nm, and the response current could be changed along with the light wavelength. When the light wavelength keeps constant, there exists a good linear relationship between the intensity of the response current and the power of the incident light, based on which the device could be used as the photo detector to collect the light information. During the changing period of the light signal, the response time of the device is several microseconds, which is acceptable working as a photo detector in our system. The testing results show that the device has good electronic and optical properties, and the fabrication procedure is also repeatable, the properties of the devices has good uniformity, which illustrates the fabrication method and procedure could be used to build the photo detector in our wearable system. Based on a series of testing results, the paper has drawn the conclusion that the photo detector fabricated could be integrated on the flexible substrate and is also suitable for the monitoring system proposed, thus made some progress on the research of the wearable monitoring system and device. Finally, some future prospect in system design aspect and device design and fabrication aspect are proposed.

The viability of a tool for fetal health monitoring

Health monitoring has become widespread these past few years. Such applications include from exercise, food intake and weight watching, to specific scenarios like monitoring people who suffer from chronic diseases. More and more we see the need to also monitor the health of new-born babies and even fetuses. Congenital Heart Defects (CHDs) are the main cause of deaths among babies and doctors do not know most of these defects. Hence, there is a need to study what causes these anomalies, and by monitoring the fetus daily there will be a better chance of identifying the defects in earlier stages. By analyzing the data collected, doctors can find patterns and come up with solutions, thus saving peoples’ lives. In many countries, the most common fetal monitor is the ultrasound and the use of it is regulated. In Sweden for normal pregnancies, there is only one ultrasound scan during the pregnancy period. There is no great evidence that ultrasound can harm the fetus, but many doctors suggest to use it as little as possible. Therefore, there is a demand for a new non-ultrasound device that can be as accurate, or even better, on detecting the FHR and not harming the baby. The problems that are discussed in this thesis include how can accurate fetus health be monitored non-invasively at home and how could a fetus health monitoring system for home use be designed. The first part of the research investigates different technologies that are currently being used on fetal monitoring, and techniques and parameters to monitor the fetus. The second part is a qualitative study held in Sweden between April and May 2016. The data for the qualitative study was collected through interviews with 21 people, 10 mothers/mothers-to-be and 11 obstetricians/gynecologists/midwives. The questions were related to the Swedish pregnancy protocol, the use of technology in medicine and in particular during the pregnancy process, and the use of an ECG based monitoring device. The results show that there is still room for improvements on the algorithms to extract the fetal ECG and the survey was very helpful in understanding the need for a fetal home monitor. Parents are open to new technologies especially if it doesn't affect the baby's growth. Doctors are open to use ECG as a great alternative to ultrasound; on the other hand, midwives are happy with the current system. The remote monitoring feature is very desirable to everyone, if such system will be used in the future.