Daniel Lai | Victoria University (original) (raw)

Books by Daniel Lai

Papers by Daniel Lai

IEEE Transactions on Antennas and Propagation, 2016

Health-care monitoring and diagnostics technology continues to be of great interest in research d... more Health-care monitoring and diagnostics technology continues to be of great interest in research due to an increasing trend in the number of people with chronic diseases. To improve accuracy and timeliness of diagnosis, electronic devices could be implanted inside human body to provide various real-time diagnostic information. However, effective technique for communicating the implant with outside world is still an open problem. Early efforts based on radio wave propagation are standardised as the Medical Implant Communication Services (MICS) for 402-405 MHz frequency range which was later adopted as Medical Devices Radiocommunications Services (MedRadio) for 401-406 MHz frequency range. Intra-body communication (IBC) is a relatively new technique that uses the human body as a channel with communication frequencies not exceeding several MHz. In this work, we propose a new analytical electromagnetic model that uses galvanically coupled IBC as an alternative to radio wave based implant communication. The model is unified in the sense that it is based on multi-layered ellipsoidal geometry that can be applied to any part of the body (i.e., head, torso, limbs etc.). Our model effectively describes influences of tissue layer thicknesses and electromagnetic properties, implant size and depth, and geometry of the body part. The model proves the security and low power consumption of IBC. The path loss characterisation of IBC implants shows lower values compared to their MICS counterparts.

Electronics, 2017

The study of human body hydration is increasingly leading to new practical applications, includin... more The study of human body hydration is increasingly leading to new practical applications, including online assessment techniques for whole body water level and novel techniques for real time assessment methods as well as characterization for fitness and exercise performance. In this review, we will discuss the different techniques for assessing hydration from electrical properties of tissues and their components and the biological relations between tissues. This will be done mainly in the context of engineering while highlighting some applications in medicine, mobile health and sports.

Proceedings of the 10th EAI International Conference on Body Area Networks, 2015

The present study investigates the inertial sensor kinematics obtained at a critical toe-control ... more The present study investigates the inertial sensor kinematics obtained at a critical toe-control event, Minimum Toe Clearance (MTC), to classify different age groups. Fourteen young and fourteen older adults performed treadmill walking at their preferred walking speed, wearing a shoe-mount inertial sensor unit measuring tri-axial acceleration and triaxial angular velocities. Three dimensional (3D) positiontime data was obtained using high accurate motion capture system. MTC timing within a gait cycle (M T CT ime), calculated using 3D motion capture data, was used to extract inertial sensor kinematics at MTC event. Mean and standard deviation of three inertial sensor acceleration features and three angular velocity features were compared between young and older individuals using t-tests. Young adults' mean anterior-posterior acceleration was greater than older adults (p=0.002). Further, standard deviations (SD) of all three accelerations and angular velocity about medio-lateral axis were greater in Older adults. The inertial sensor kinematics obtained at M T CT ime were able to classify young and older adults gait with 91.2% accuracy using a Support Vector Machine (SVM) classifier. The findings of the present study suggest that by employing SVM techniques, a portable inertial sensor system could be used to identify gait degeneration due to ageing and has the potential for wider applications in gait identification for falls-risk minimization.

Journal of medical and biological engineering, 2017

Intrabody communication (IBC) is a promising data communication technique for body area networks.... more Intrabody communication (IBC) is a promising data communication technique for body area networks. This short-distance communication approach uses human body tissue as the medium of signal propagation. IBC is defined as one of the physical layers for the new IEEE 802.15.6 or wireless body area network (WBAN) standard, which can provide a suitable data rate for real-time physiological data communication while consuming lower power compared to that of radio-frequency protocols such as Bluetooth. In this paper, impulse radio (IR) IBC (IR-IBC) is examined using a field-programmable gate array (FPGA) implementation of an IBC system. A carrier-free pulse position modulation (PPM) scheme is implemented using an IBC transmitter in an FPGA board. PPM is a modulation technique that uses time-based pulse characteristics to encode data based on IR concepts. The transmission performance of the scheme was evaluated through signal propagation measurements of the human arm using 4- and 8-PPM transmi...

TENCON 2015 - 2015 IEEE Region 10 Conference, 2015

Intrabody communications (IBC) is a promising data communication technique for body area networks... more Intrabody communications (IBC) is a promising data communication technique for body area networks in biomedical applications. This short distance communication approach transmits signals through body tissue forming a wireless network among on-body sensors. It is defined as one of the physical layers for the new IEEE 802.15.6 or Wireless Body Area Network (WBAN) standard. It is meaningful to investigate the characterization of the IBC communication system for wearable and implantable biomedical applications. In this paper, an impulse radio (IR) type of transmitter was developed for galvanic coupling type IBC. A carrier-free transmission is implemented in a field programmable gate array (FPGA) board based on a pulse position modulation (PPM) scheme. PPM is a modulation technique which uses time based pulse characteristics to encode data and is based on impulse radio ideas. Results demonstrate that there is 40 dB attenuation after 20 cm data transmission through human arm. Additionally, the Signal-to-noise ratio (SNR) decreases about 8.0 dB for a range of arm distances (5-50 cm) between transmitter and receiver electrodes with the stable noise and various signal amplitude. The variations of the channel SNR is measured approximately 0.2 dB/cm for 5-50 cm on-body distances. The behavior of SNR shows how signals will propagate through the human body communication channel.

Electronics, 2016

Recent advances in biomedical sensors, data acquisition techniques, microelectronics and wireless... more Recent advances in biomedical sensors, data acquisition techniques, microelectronics and wireless communication systems opened up the use of wearable technology for ehealth monitoring. We introduce a galvanic coupled intrabody communication for monitoring human body hydration. Studies in hydration provide the information necessary for understanding the desired fluid levels for optimal performance of the body's physiological and metabolic processes during exercise and activities of daily living. Current measurement techniques are mostly suitable for laboratory purposes due to their complexity and technical requirements. Less technical methods such as urine color observation and skin turgor testing are subjective and cannot be integrated into a wearable device. Bioelectrical impedance methods are popular but mostly used for estimating total body water with limited accuracy and sensitive to 800 mL-1000 mL change in body fluid levels. We introduce a non-intrusive and simple method of tracking hydration rates that can detect up to 1.30 dB reduction in attenuation when as little as 100 mL of water is consumed. Our results show that galvanic coupled intrabody signal propagation can provide qualitative hydration and dehydration rates in line with changes in an individual's urine specific gravity and body mass. The real-time changes in galvanic coupled intrabody signal attenuation can be integrated into wearable electronic devices to evaluate body fluid levels on a particular area of interest and can aid diagnosis and treatment of fluid disorders such as lymphoedema.

Proceedings of the 4th International Conference on Wireless Mobile Communication and Healthcare - "Transforming healthcare through innovations in mobile and wireless technologies", 2014

Intrabody communications (IBC) is a novel communication technique which uses the human body itsel... more Intrabody communications (IBC) is a novel communication technique which uses the human body itself as the signal propagation medium. This communication method is categorized as a physical layer of IEEE 802.15.6 or Wireless Body Area Network (WBAN) standard. It is significant to investigate the IBC systems to improve the transceiver design characteristics such as data rate and power consumption. In this paper, we propose a new IBC transmitter implementing pulse position modulation (PPM) scheme based on impulse radio. A FPGA is employed to implement the architecture of a carrierfree PPM transmission. Results demonstrate the data rate of 1.56 Mb/s which is suitable for the galvanic coupling IBC method. The PPM transmitter power consumption is 2.0 mW with 3.3 V supply voltage. Having energy efficiency as low as 1.28 nJ/bit provides an enhanced solution for portable biomedical applications based on body area networks.

2014 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014

ABSTRACT Intrabody communications (IBC) is a new physical layer outlined in the recently ratified... more ABSTRACT Intrabody communications (IBC) is a new physical layer outlined in the recently ratified IEEE 802.15.6 Wireless Body Area Network (WBAN) standard. This data communication method uses the human body itself as the signal propagation medium. It is significant to investigate the signal characteristics for baseband digital data transceiver design in IBC. In this paper, we present preliminary channel attenuation characteristics of a time division multiple access (TDMA) scheme implemented based on baseband digital signal transmission. A digital block implemented on a field-programmable gate array (FPGA) board as well as a digital Pulse Generator are employed as the IBC transmitters. The timeslot occupancy is simulated by adjusting the duty cycle of a square wave of varying frequencies. The measurements using FPGA indicate the signal attenuation of 32.76 and 27.82 dB at frequency of 10 and 25 MHz, respectively, for digital signals with 50% duty cycle. In addition, the attenuation of signal with 20% and 50% duty cycle at 50 MHz are 32.76 and 30.63 dB when Pulse Generator is used as the IBC transmitter. The variation of duty cycle in pulses was then used to simulate a time division multiplexed transmission scheme. It was observed that the attenuation decreases around 4.0 dB when data pulses are increasingly present from 1 to 5 timeslots. Therefore, digital baseband signals deployed in a time division multiplexed mode with higher timeslot occupancy leads to lower attenuation for IBC transmissions.

The 2012 International Joint Conference on Neural Networks (IJCNN), 2012

Identifying different walking conditions is essential in order to monitor the activities of elder... more Identifying different walking conditions is essential in order to monitor the activities of elderly population for active living or fast recovery of a patient following a surgery or even for prognosis and diagnosis of several conditions like Parkinson's disease. This paper looks at automatically detecting three different walking conditions (walking normally with preferred walking speed (PWS), walking while carrying a glass of water, and walking blind folded) using inertial sensor data. Tri-axial accelerometers and gyroscopes were used to acquire movement data from both feet during the three gait tasks. Five healthy young subjects undertook 10 trials per condition on a GAITRite mat. Statistical properties such as the mean, standard deviation (std), skewness (skew) and kurtosis were calculated for each trial that included several gait cycles' data. Altogether 48 features were analyzed using Fuzzy Clustering Mean (FCM) algorithm to verify the separable nature of sensor data. The results show that three clusters could be found with an almost equal number of points; however the membership was not high enough to result in complete discrete clusters. Then three different Support Vector Machine (SVM) classifiers were used to examine whether the conditions could be automatically classified based on the features that were extracted from inertial sensor data. The results indicate 83-84% of accurate classification of the three gait conditions with three SVM algorithms. The study demonstrates that the inertial sensor data could be used to classify differences in walking conditions using powerful computational intelligence techniques.

Encyclopedia of Healthcare Information Systems

Proceedings. 2005 IEEE International Joint Conference on Neural Networks, 2005., 2005

The training of Support Vector Machines using the decomposition method has one drawback; namely t... more The training of Support Vector Machines using the decomposition method has one drawback; namely the selection of working sets such that convergence is as fast as possible. It has been shown by Lin that the rate is linear in the worse case under the assumption that all bounded Support Vectors have been determined. The analysis was done based on the change in the objective function and under a SVMlight selection rule. However, the rate estimate given is independent of time and hence gives little indication as to how the linear convergence speed varies during the iteration. In this initial analysis, we provide a treatment of the convergence from a gradient contraction perspective. We propose a necessary and sufficient condition which when satisfied provides strict linear convergence of the algorithm. The condition can also be interpreted as a basic requirement for a sequence of working sets in order to achieve such a convergence rate. Based on this condition, a time dependant rate estimate is then further derived. This estimate is shown to monotonically approach unity from below.

Page 1. ORGANISATION General Co-Chairs Marimuthu Palaniswami, University of Melbourne, Australia ... more Page 1. ORGANISATION General Co-Chairs Marimuthu Palaniswami, University of Melbourne, Australia Peter Corke, Queensland University of Technology, Australia Slaven Marusic, University of Melbourne, Australia Symposium and Workshop Chairs Symposium on Sensor Networks Salil Kanhere, University of New South Wales, Australia Athanassios Boulis, NICTA, Australia Symposium on Advances in Optimization for Distributed Control, Information ...

Page 1. Organisation General Chair M. Palaniswami (University of Melbourne, Australia) Symposium ... more Page 1. Organisation General Chair M. Palaniswami (University of Melbourne, Australia) Symposium and Workshop Chairs Symposium on Sensor Networks Paul JM Havinga (University of Twente, The Netherlands) Tim Wark (CSIRO, Australia) Symposium on Sensor Fusion, Intelligent Sensors and Applications Danil Prokhorov (Toyota, USA) Thomas Hanselmann (University of Melbourne, Australia) Symposium on Information Processing in Sensor Networks Salim Bouzerdoum (University of Wollongong, Australia) ...

IEEE reviews in biomedical engineering, Jan 10, 2017

Wireless Body Area Networks (WBAN) has attained increasing popularity as the next generation fram... more Wireless Body Area Networks (WBAN) has attained increasing popularity as the next generation framework of wearable technologies for human monitoring. Invasive or non-invasive wearable sensors designed in WBAN are worn to gather vital information. Biofeedback is a recent concept where collected data is used to generate actuation signals in WBANs. Applications can be seen in various areas such as sports (e.g. locomotor velocity) or medical (e.g. blood pressure measurement). However, since the body is closely regulated, the next generation WBAN technology must be smart enough to react to monitored data. The main aim of the paper is to review the current state of biofeedback and actuation technology on WBANs in terms of its structure, applications, benefits, and control approaches. The emphasis on the specific requirements when applying biofeedback to humans will be highlighted and discussed. Challenges and open research issues will be concluded at the end.

Sensors, 2022

Powered ankle exoskeletons (PAEs) are robotic devices developed for gait assistance, rehabilitati... more Powered ankle exoskeletons (PAEs) are robotic devices developed for gait assistance, rehabilitation, and augmentation. To fulfil their purposes, PAEs vastly rely heavily on their sensor systems. Human–machine interface sensors collect the biomechanical signals from the human user to inform the higher level of the control hierarchy about the user’s locomotion intention and requirement, whereas machine–machine interface sensors monitor the output of the actuation unit to ensure precise tracking of the high-level control commands via the low-level control scheme. The current article aims to provide a comprehensive review of how wearable sensor technology has contributed to the actuation and control of the PAEs developed over the past two decades. The control schemes and actuation principles employed in the reviewed PAEs, as well as their interaction with the integrated sensor systems, are investigated in this review. Further, the role of wearable sensors in overcoming the main challeng...

Nanomaterials

Biocompatible carbon quantum dots (CQDs) have recently attracted increased interest in biomedical... more Biocompatible carbon quantum dots (CQDs) have recently attracted increased interest in biomedical imaging owing to their advantageous photoluminescence properties. Numerous precursors of fluorescent CQDs and various fabrication procedures are also reported in the literature. However; the use of concentrated mineral acids and other corrosive chemicals during the fabrication process curtails their biocompatibility and severely limits the utilization of the products in cell bio-imaging. In this study; a facile; fast; and cost-effective synthetic route is employed to fabricate CQDs from a natural organic resource; namely bread; where the use of any toxic chemicals is eliminated. Thus; the novel chemical-free technique facilitated the production of luminescent CQDs that were endowed with low cytotoxicity and; therefore; suitable candidates for bioimaging sensors. The above mentioned amorphous CQDs also exhibited fluorescence over 360–420 nm excitation wavelengths; and with a broad emissi...

IEEE reviews in biomedical engineering, Jan 18, 2018

Over the past six decades there has been tremendous progress made in the field of medical implant... more Over the past six decades there has been tremendous progress made in the field of medical implant communications. A comprehensive review of the progress, current state-of-the-art and future direction is presented in this chapter. Implanted Medical Devices (IMDs) are designed mainly for the purpose of diagnostic, therapeutic and assitive applications in heathcare, active living and sports technology. The primary target of implanted medical devices (IMDs) design revolve around reliable communications, sustainable power sources, high degree of miniaturisation while maintaining bio-compatibility to surrounding tissues adhering to the human safety limits set by appropriate guidelines. The role of internet of things (IoT) and intelligent data analysis in implant device networks as future research is presented. Lastly, in addition to reviewing the state-of-the art, a novel intuitive lower bound on implant size is presented.

International Journal of Distributed Sensor Networks

Accurate measurement of hand forces in motorbike riding is highly desirable for studies of safe r... more Accurate measurement of hand forces in motorbike riding is highly desirable for studies of safe riding. In this paper, we implement a force-sensing glove system for measuring real-time hand forces during motorbike riding with the aim of giving feedback to the riders. It consists of a pair of gloves with tactile sensors suitably mounted and configured for data acquisition via a wireless smartphone. A novel calibration method is developed for dynamic calibration considering force measurement in natural operation and environments. Consequently, a series of data classification algorithms ensure accurate hand performance feedbacks for motorbike riders. The feedback data could potentially alert the riders to predict and prevent accidents. Validation tests demonstrate that this force-sensing glove system has a strong potential as a tool for hand performance monitoring in real environment.