Monitoring the pulse arrival time using optical fibre sensors

The plastic optical fibre (POF) is widely explored in various sensor applications. The non-toxic and biochemical inertness properties of the material make it safe to be applied on the human skin and hence opens up a wealth of wearable opportunities. To date, no one has investigated the combination of POFs and textile electrodes that are well suited to smart textile applications. Therefore, in this thesis, POFs were explored as an extrinsic sensor for the measurement of photoplethysmogram (PPG) on the human body. Further, a conductive textile electrode was utilized for Electrocardiogram (ECG) measurement. The ECG and the PPG signals were synchronized using a Nexus-10 MK II data acquisition device along with Matlab software for subsequent analysis. In this study, the delay time between the ECG and PPG are calculated and denoted as pulse arrival time (PAT). The PAT is grouped into three categories which depend on the position of the PPG signal measured at the finger (PPTf), wrist (PATw) and underfoot (PATt). A relationship between mean PAT (15 beats) and instantaneous PAT (a single beat) with blood pressure (BP) was investigated on thirteen healthy male volunteers (aged between 17 to 42 years) through a pedal exercise. A linear regression model was applied to mean/instantaneous PAT-BP data and the absolute correlation coefficient, ІrІ was determined on each volunteer. The results show that the PAT is well correlated with systolic BP, especially for PATf (instantaneous and mean PAT), with 100% of volunteers achieving ІrІ > 0.5. For PAT and diastolic BP correlation, majority of volunteers achieving ІrІ < 0.5 for all categories, PATf, PATw and PATt (instantaneous and mean PAT). Next, a new one-step calibration method and a pedal exercise calibration method were evaluated to estimate systolic BP during a tilt table experiment. The results show that the one-step calibration method at the finger show a marginally better correlation coefficient, (r = 0.65) compared to the pedal exercise calibration method (r = 0.45), when estimating systolic BP. Advantageously, the one-step calibration method is simple and time-saving because it only required one measurement of BP using a cuff-based BP monitor as a reference. Lastly, a tubular cardiovascular phantom system was proposed and developed to simulate the PDT measurement in a controlled environment. The results of the phantom study showed a similar pattern to the PTT in human model, thus indicating that the system is able to simulate the PDT for sensor validation purposes

Cuff-less continuous blood pressure monitoring system using pulse transit time techniques

This paper describes the development of a continuous cuff-less blood pressure system based on the pulse transit time (PTT) technique. In this study, PTT is defined by two different approaches denoted as PTT1 and PTT2. PTT1 is the time difference between the R-wave peak of the Electrocardiogram (ECG) and the peak of the Photoplethysmogram (PPG). PTT2 is the time difference between two peak PPG signals on same cardiac cycle at different positions on the body. The ECG is acquired on the chest using 3 lead electrodes and a reflection mode optical sensor is deployed on brachial artery and fingertip to monitor the PPGs. These data were synchronized using a National Instruments data acquisition card along with Matlab software for subsequent analysis. A wrist-type cuff-based blood pressure device was used to measure blood pressure on the right hand. Brachial blood pressure was measured on the upper left arm using oscillometric blood pressure monitor. Experiments were conducted by elevating the right hand at different position to investigate variability of PTT under the effects of hydrostatic pressure. Next the variability of PTT due to blood pressure changes during a Valsalva maneuver was investigated. The result shows that the PTT1 is inversely proportional to blood pressure in both experiments. Meanwhile, there is weak correlation between PTT2 and blood pressure measurement which suggests that by excluding the pre-ejection period (PEP) time in PTT calculation may reduce the accuracy of PTT for blood pressure measurement. In conclusion, PTT measurement between ECG and PPG signals has potential to be a reliable technique for cuff-less blood pressure measurement

Development of tubular cardiovascular phantom system for pulse transit time simulation

This paper presents on the development of a tubular cardiovascular phantom system to simulate pulse transit time (PTT). The PTT defined as the delay time between two pulses in one cardiac cycle has been shown to be promising method for cuffless continuous blood pressure (BP) measurement. However most of the PTT measurement was performed on human subjects, thus giving a difficulty in validating sensor performance due to variability of BP. Therefore, a cardiovascular phantom system was proposed for simulate the PTT measurement. An electronic controlled module was developed to control pump operation for pulse generation. Plastic optical fibre (POF) sensors were used to measure the pulse signal on the flexible tube and the results were compared with an in-line pressure sensor. In this experiment, the delay time between two pulses were calculated offline using Matlab software and correlated with pulse pressure. The result demonstrate that the pulse delay time recorded by both sensors decreased with increase of pulse rate and pulse pressure. These results on the phantom study showed similar pattern to the human model, thus indicating that the system is able to simulate PTT for sensor validation purposes

An Implementation of POPBL for Analog Electronics (BEL10203) Course at the Faculty Of Electrical and Electronic Engineering, Uthm

A Project Oriented Problem Based Learning (POPBL) has been introduced to the first year students in the Analog Electronics (BEL10203) course at the Faculty of Electrical and Electronic Engineering, UTHM. The aim is to design an electronic circuit using transistors and diodes that can function as electronic appliances with low cost, low power consumption, and has the features of smart and portable. The total of 143 students were divided into groups and assigned to setup an electronic based company that will be manufacturing the electronic product. Each group had to conduct their regular meetings and develop different kind of products with their creativity. The overall evaluation is divided for both lecturer and peer assessment which carried 20% of their course work. The assessment covered 60% of evaluation for the group management, attitude, progress presentation, report writing while another 40% for the functionality and features of their product. As a result, the POPBL session has increased the student&rsquo;s ability to analyze and design an analog circuit using various kinds of transistors and diodes. They also gained practical understanding on transistor and diode operation. The POPBL not only expanded their experience in using software tools for circuit design and simulation, but also developed greater awareness to conduct professional presentation and technical report. They also learned to work as professional, keen to ethical responsibilities and committed to the group. The analysis conducted has shown that 95% of the students agreed that the problem given helped them understands better the course syllabus and developed a good problem solving skills

Blood pressure estimation with complexity features from electrocardiogram and photoplethysmogram signals

A novel method for the continual, cuff-less estimation of the systolic blood pressure (SBP) and diastolic blood pressure (DBP) values based on signal complexity analysis of the photoplethysmogram (PPG) and the electrocardiogram (ECG) is reported. The proposed framework estimates the blood pressure (BP) values obtained from signals generated from 14 volunteers subjected to a series of exercise routines. Herein, the physiological signals were first pre-processed, followed by the extraction of complexity features from both the PPG and ECG. Subsequently the complexity features were used in regression models (artificial neural network (ANN), support vector machine (SVM) and LASSO) to predict the BP. The performance of the approach was evaluated by calculating the mean absolute error and the standard deviation of the predicted results and compared with the recommendations made by the British Hypertension Society (BHS) and Association for the Advancement of Medical Instrumentation. Complexity features from the ECG and PPG were investigated independently, along with the combined dataset. It was observed that the complexity features obtained from the combination of ECG and PPG signals resulted to an improved estimation accuracy for the BP. The most accurate DBP result of 5.15 ± 6.46 mmHg was obtained from ANN model, and SVM generated the most accurate prediction for the SBP which was estimated as 7.33 ± 9.53 mmHg. Results for DBP fall within recommended performance of the BHS but SBP is outside the range. Although initial results are promising, further improvements are required before the potential of this approach is fully realised

Monitoring the pulse arrival time using optical fibre sensors

The plastic optical fibre (POF) is widely explored in various sensor applications. The non-toxic and biochemical inertness properties of the material make it safe to be applied on the human skin and hence opens up a wealth of wearable opportunities. To date, no one has investigated the combination of POFs and textile electrodes that are well suited to smart textile applications. Therefore, in this thesis, POFs were explored as an extrinsic sensor for the measurement of photoplethysmogram (PPG) on the human body. Further, a conductive textile electrode was utilized for Electrocardiogram (ECG) measurement. The ECG and the PPG signals were synchronized using a Nexus-10 MK II data acquisition device along with Matlab software for subsequent analysis. In this study, the delay time between the ECG and PPG are calculated and denoted as pulse arrival time (PAT). The PAT is grouped into three categories which depend on the position of the PPG signal measured at the finger (PPTf), wrist (PATw) and underfoot (PATt). A relationship between mean PAT (15 beats) and instantaneous PAT (a single beat) with blood pressure (BP) was investigated on thirteen healthy male volunteers (aged between 17 to 42 years) through a pedal exercise. A linear regression model was applied to mean/instantaneous PAT-BP data and the absolute correlation coefficient, ІrІ was determined on each volunteer. The results show that the PAT is well correlated with systolic BP, especially for PATf (instantaneous and mean PAT), with 100% of volunteers achieving ІrІ > 0.5. For PAT and diastolic BP correlation, majority of volunteers achieving ІrІ < 0.5 for all categories, PATf, PATw and PATt (instantaneous and mean PAT). Next, a new one-step calibration method and a pedal exercise calibration method were evaluated to estimate systolic BP during a tilt table experiment. The results show that the one-step calibration method at the finger show a marginally better correlation coefficient, (r = 0.65) compared to the pedal exercise calibration method (r = 0.45), when estimating systolic BP. Advantageously, the one-step calibration method is simple and time-saving because it only required one measurement of BP using a cuff-based BP monitor as a reference. Lastly, a tubular cardiovascular phantom system was proposed and developed to simulate the PDT measurement in a controlled environment. The results of the phantom study showed a similar pattern to the PTT in human model, thus indicating that the system is able to simulate the PDT for sensor validation purposes

Design and Fabrication of Batio3 Humidity Sensor Using Thick Film Screen Printing Technique

Thick film sensor technology has been recognized as an important technology in sensor manufacturing for the last decade. The technology contributes to the sensor development with the exploitation of the film itself as a primary sensing device. Most ceramic materials have been investigated as a humidity sensor mainly on porous structure prepared by thick film technology. These films have microstructure properties similar to those of sintered porous bodies, but the dimensions of the sensing devices can be reduced, which then can be used in hybrid circuits. In this work, two types of analyses will be made based on Barium Titanate (BaTiO3) dielectric material. The First one is to analysis the electrical properties of BaTiO3 material in bulk and thick film forms and second analysis is to characterize thick film BaTiO3 for a humidity sensor at room temperature. The BaTiO3 powder was prepared through solid state reaction using a raw material Barium Carbonate (BaCO3) and Titanium Dioxide (TiO2). The thick film paste was prepared by mixing an organic vehicle with the sintered powder in appropriate ratio. The paste was then screen printed onto a ceramic substrate in an interdigitated electrode pattern using DEK J1202 screen printing machine. The dielectric property of BaTiO3 was investigated by varying the frequency in the range of 10Hz to 10 MHz using the Impedance Analyzer. The characterization of the thick film sensor with response to the Relative Humidity (%RH) was carried out in the Humidity Climatic Chamber in the range of 20%RH to 95%RH. LCR meter and PIC conditioning unit was used to measure the response of the BaTiO3 thick film sample with the changes of the Relative Humidity.. The results showed that the dielectric response of the BaTiO3 material in bulk and film samples are the same, based on the quasi dc concept. A smaller gap of interdigitated electrode pattern gave a higher response in dielectric properties compared to the bigger gap. The BaTiO3 thick film sensor showed decrement in resistance and increment in capacitance with respect to the increases of Relative Humidity (RH). The voltage-humidity characteristic of the sensor showed a good linearity and the sensor response time is faster than the recovery time. The PIC conditioning circuit is designed to convert the analogue voltage into digital value and display the measurement result through Liquid Crystal Display (LCD) to make the system more user-friendly. As a conclusion, BaTiO3 thick film shows a good promising material to be used as a humidity sensor based on thick film screen printing technology

Cuff-Less Continuous Blood Pressure Monitoring System Using Pulse Transit Time Techniques

This paper describes the development of a continuous cuff-less blood pressure system based on the pulse transit time (PTT) technique. In this study, PTT is defined by two different approaches denoted as PTT1 and PTT2. PTT1 is the time difference between the R-wave peak of the Electrocardiogram (ECG) and the peak of the Photoplethysmogram (PPG). PTT2 is the time difference between two peak PPG signals on same cardiac cycle at different positions on the body. The ECG is acquired on the chest using 3 lead electrodes and a reflection mode optical sensor is deployed on brachial artery and fingertip to monitor the PPGs. These data were synchronized using a National Instruments data acquisition card along with Matlab software for subsequent analysis. A wrist-type cuff-based blood pressure device was used to measure blood pressure on the right hand. Brachial blood pressure was measured on the upper left arm using oscillometric blood pressure monitor. Experiments were conducted by elevating the right hand at different position to investigate variability of PTT under the effects of hydrostatic pressure. Next the variability of PTT due to blood pressure changes during a Valsalva maneuver was investigated. The result shows that the PTT1 is inversely proportional to blood pressure in both experiments. Meanwhile, there is weak correlation between PTT2 and blood pressure measurement which suggests that by excluding the pre-ejection period (PEP) time in PTT calculation may reduce the accuracy of PTT for blood pressure measurement. In conclusion, PTT measurement between ECG and PPG signals has potential to be a reliable technique for cuff-less blood pressure measurement

Thick film paste preparation and characterization of BaTiO3 for humidity sensor

A dielectric material of BaTiO3 powder was prepared using solid state reaction from raw materials; BaCO3 and TiO2. A study was conducted to prepare the BaTiO3 thick film paste by mixing the organic vehicle and the sintered powder in ratio of 30:70. The organic vehicle was formed from suspending ethyl cellulose resins into terpineol solvent in a specific ratio. The paste was printing onto ceramic substrate by using DEK J1202 thick film screen printer machine. The recipe and the process in producing BaTiO3 thick film paste was then established. The electrical properties of screen-printed BaTiO3 were investigated in an interdigitated electrode pattern. Experimental results show that the smaller gap between two adjacent electrodes gives higher capacitance and lower resistance value, thus provide better response time in detecting capacitor changes for sensor application. An equivalent circuit to represent the dialectic mechanism of the BaTiO3 thick film sample has also been established

Development of 3-stage hybrid computer aided design (3-HCAD) system for multi-modal medical images to identify brain tumor

The latest developments in medical imaging and computer-aided solutions for image processing problems attract attention of various researchers to impart their research in the medical imaging field.   Designing and developing efficient algorithms to present the medical information effectively have become critical areas of research in this field. A 3-Stage Hybrid Computer Aided Design system is introduced to identify Brain tumor in earlier stages by extracting meaningful information from multimodal medical images. The preferred multi-modality images is Magnetic Resonance Imaging (MRI) and Computed Tomography (CT). The CAD system proposed in this paper can eliminate the dependency on human operators as it is an efficient software-based system. The first stage in this model consists of image pre-processing with Wavelet and Curvelet transforms. The second stage of the CAD system is an image segmentation process, which involves a combination of Wavelet Transform and Watershed Technique. The third stage involves image fusion, where the individually segmented CT and MRI images are fused together to obtain an integrated complementary information from two different images. This is followed by decomposing CT and MRI images using the Dual Tree Complex Wavelet Transform (DTCWT) and Nonsubsampled Contourlet Transform (NSCT).