Biosignal Acquisition Research Articles

Communication Protocol for Wireless Sensor Network, Dedicated for Real Time Biosignal Acquisition, Implemented on Top of Contiki OS

Abstract The aim of this paper is to present a communication protocol designed for Wireless Sensor Network based biosignal measurement system. The protocol addressees the issue of time synchronization of the measuring nodes and real time transmission of the acquired measurements. We run the Contiki OS on the sensor nodes and the protocol was implemented as a process. The proposed protocol was tested on custom built hardware, developed by our team for biosignal measurement.

SMoBAICS

Simulation and modelling are powerful methods in computer aided therapy, rehabilitation monitoring, identification and control. The smart modular biosignal acquisition and identification system (SMoBAICS) provides methods and techniques to acquire electromyogram (EMG)- and electroneurogram (ENG)-based data for the evaluation and identification of biosignals. In this paper the author focuses on the development, integration and verification of platform technologies which support this entire data processing. Simulation and verification approaches are integrated to evaluate causal relationships between physiological and bioinformatical processes. Based on this we are stepping up of efforts to develop substitute methods and computer-aided simulation models with the objective of reducing animal testing. This work continues the former work about system identification and biosignal acquisition and verification systems presented in (Bohlmann et al., 2010), (Klinger and Klauke, 2013), (Klinger, 2014). This paper focuses on the next generation of an embedded data acquisition and identification system and its flexible platform architecture. Different application scenarios are shown to illustrate the system in different application fields. The author presents results of the enhanced closed-loop verification approach and of the signal quality using the Cuff-electrode-based ENG-data acquisition system.

Preparation and Property Evaluation of Conductive Hydrogel Using Poly (Vinyl Alcohol)/Polyethylene Glycol/Graphene Oxide for Human Electrocardiogram Acquisition.

Conductive hydrogel combined with Ag/AgCl electrode is widely used in the acquisition of bio-signals. However, the high adhesiveness of current commercial hydrogel causes human skin allergies and pruritus easily after wearing hydrogel for electrodes for a long time. In this paper, a novel conductive hydrogel with good mechanical and conductive performance was prepared using polyvinyl alcohol (PVA), polyethylene glycol (PEG), and graphene oxide (GO) nanoparticles. A cyclic freezing–thawing method was employed under processing conditions of −40 °C (8 h) and 20 °C (4 h) separately for three cycles in sequence until a strong conductive hydrogel, namely, PVA/PEG/GO gel, was obtained. Characterization (Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy) results indicated that the assembled hydrogel was successfully prepared with a three-dimensional network structure and, thereafter, the high strength and elasticity due to the complete polymeric net formed by dense hydrogen bonds in the freezing process. The as-made PVA/PEG/GO hydrogel was then composited with nonwoven fabric for electrocardiogram (ECG) electrodes. The ECG acquisition data indicated that the prepared hydrogel has good electro-conductivity and can obtain stable ECG signals for humans in a static state and in motion (with a small amount of drift). A comparison of results indicated that the prepared PVA/PEG/GO gel obtained the same quality of ECG signals with commercial conductive gel with fewer cases of allergies and pruritus in volunteer after six hours of wear.

Low-power low-data-loss bio-signal acquisition system for intelligent electrocardiogram detection

Low-power low-data-loss bio-signal acquisition system for intelligent electrocardiogram detection

Enhancing Video Chat Applications for Home Health Care

Background: Estimates show that up to 87% of seniors would like to “age in place.” Often, such people are remote from their families and health care providers. Acquisition and telemetry of data and bio-signals from personal health care instrumentation is of great value, but we feel that this does not tell the complete story, because we are dealing with humans. A brief video chat, via personal computer, can usually provide a great deal of information concerning a person’s well-being. An individual’s mood, physical status, and energy level and the state of their surroundings can frequently be determined in a one-minute video chat. While these evaluations are qualitative, they can be very useful in answering the simple, important question “Is this person OK?” A video chat can also help build constructive social bonds between patients and providers because the telecommunication is no longer “faceless.” People who are aging in place are generally not the best computer users. Even if a person is proficient with the use of computers, issues with vision and manual dexterity can present obstacles to the use of video chat applications such as Skype. We have designed and implemented a low-cost system, comprised of a small “helper” program and a wired keypad, which operates with a personal computer and obviates the difficulties experienced by many less experienced and older users. Very simply, this system makes it easier for many people to communicate with their families and healthcare providers. Objective: Our goal was to simplify the use of video chat applications. A conventional desktop is often visually cluttered or has one application window obscuring another. Navigation with a mouse or other pointing device can be difficult for people with impaired vision and those with tremors, arthritis, or other dexterity limiting factors. We designed and built a “helper” program that, in conjunction with a dedicated large symbol keypad, lets a user initiate a video chat just by pressing a couple of buttons. Methods: At present we have conducted a small pilot study (N=8) with naïve computer users who want to video chat with family members. Participants in the study were chosen because they had difficulty initiating video chats. We asked this group to use our system and measured time required to initiate a video chat. Results: All subjects were able to initiate video chats in <30 seconds. The users were all able to terminate the chats when desired. In simple terms, the naïve users were able to start and end calls when they wanted to. Users expressed satisfaction at being able to control this aspect of their computers without technical support from others and enjoyed chat interactions. Conclusions: Video chat applications can be made simpler and easier to use, empowering a person who is aging in place to engage with family and healthcare providers.

Reconfigurable Multiparameter Biosignal Acquisition SoC for Low Power Wearable Platform.

A low power and low noise reconfigurable analog front-end (AFE) system on a chip (SoC) for biosignal acquisition is presented. The presented AFE can be reconfigured for use in electropotential, bioimpedance, electrochemical, and photoelectrical modes. The advanced healthcare services based on multiparameter physiological biosignals can be easily implemented with these multimodal and highly reconfigurable features of the proposed system. The reconfigurable gain and input referred noise of the core instrumentation amplifier block are 25 dB to 52 dB, and 1 μVRMS, respectively. The power consumption of the analog blocks in one readout channel is less than 52 μW. The reconfigurable capability among various modes of applications including electrocardiogram, blood glucose concentration, respiration, and photoplethysmography are shown experimentally.

Overview of Contemporary Low-cost sEMG Hardware for Applications in Human Factors and Ergonomics

For decades, surface electromyography (sEMG) has been one of the essential methods of Human Factors and Ergonomics. Although capturing sEMG data is relatively easy, proper interpretation of acquired data is possible only with sufficient background in electrophysiology, muscle mechanics and muscle functions. As the last decade has made biosignal acquisition more accessible, the current overview discusses the intrinsic properties of contemporary low-cost sEMG acquisition systems and proposes applications of sEMG for Human Factors and Ergonomics.

Improving Detection Accuracy of Memristor-Based Bio-Signal Sensing Platform.

Recently a novel neuronal activity sensor exploiting the intrinsic thresholded integrator capabilities of memristor devices has been proposed. Extracellular potentials captured by a standard bio-signal acquisition platform are fed into a memristive device which reacts to the input by changing its resistive state (RS) only when the signal ampitude exceeds a threshold. Thus, significant peaks in the neural signal can be stored as non-volatile changes in memristor resistive state whilst noise is effectively suppressed. However, as a memristor is subjected to increasing numbers of supra-threshold stimuli during practical operation, it accumulates (RS) changes and eventually saturates. This leads to severely redsignaluced neural activity detection capabilities. In this work we explore different signal processing and memristor operating procedure strategies in order to improve the detection rate of significant neuronal activity events. We analyse the data obtained from a single-memristive device biased with a reference neural recording and observe that performance can be improved markedly by a) increasing the frequency at which the memristor is reset to an initial resistive state where it is known to be highly responsive, b) appropriately preconditioning the input waveform through application of gain and offset in order to optimally exploit the intrinsic device behaviour. All results are validated by benchmarking obtained spike detection performance against a state-of-the-art template matching system utilising computationally-heavy, multi-dimensional, principal component analysis.

Selected design issues of the medical cyber-physical system for telemonitoring pregnancy at home

The telemonitoring problem of high-risk pregnancies at home is introduced, and some design issues of the monitoring system are identified. A Medical Cyber-Physical System (MCPS) approach has been taken. Various MCPS design issues and requirements, like: interaction of caregivers and a patient with the MCPS system, Plug-and-Play architecture, maintenance support for caregivers, interoperability of medical devices, medical workflows automation, dependability of the system, smart alerting, and intelligent acquisition of biosignals, have been addressed. The telecare system consists of the Body Area Network (BAN) of advanced sensors that are interconnected on a body of a pregnant woman, the Personal Area Network (PAN) that is responsible for embedded processing of physical signals, smart alerting, an intelligent human-machine-interface, and a reliable transmission channel to the Surveillance Centre located in a hospital or a local medical centre. The system integrates the new strategy for abdominal signal acquisition and analysis based on the smart selection of algorithms realized in the mobile instrumentation of PAN. Dependable telemedical systems, when broadly deployed, will provide a high societal value to high-risk pregnant women, especially those in dispersed rural areas.

Management Framework for Biosignals in Biomedical Studies: From Study Design to Data Statistics

A centralized and structured management framework for biosignals is proposed. This framework is dedicated to design biomedical studies, acquire and store biosignals and the associated metadata, as well as validate, synchronize, view, and evaluate these signals from an individual study-related perspective. We introduce a five-layer model as the basis of the framework to facilitate data management, which includes the acquisition, validation, postprocessing, and statistics layers, as well as the vertical presentation layer. The strategic interaction between external data (i.e., metadata) and internal data (i.e., recorded biosignals) is defined to favor high-quality results and sustainability of recorded data. For the first time, a systematic software solution was designed to mimic the proposed layer model and to reasonably combine internal and external data management using microservices within a private cloud. Researchers can individually access and manipulate all data using a client implementation or a Web browser in order to address research-related questions, whereas developers can easily implement modular functions and algorithms. A simplified implementation of the proposed framework shows its strong potential in the unification and structuring of biomedical studies as well as in the associated acquisition, storage, and analysis of biosignals.

生体信号デバイスを用いた電動車いすの操縦に関する研究

生体信号デバイスを用いた電動車いすの操縦に関する研究

Hardware-Algorithms Co-Design and Implementation of an Analog-to-Information Converter for Biosignals Based on Compressed Sensing.

We report the design and implementation of an Analog-to-Information Converter (AIC) based on Compressed Sensing (CS). The system is realized in a CMOS 180 nm technology and targets the acquisition of bio-signals with Nyquist frequency up to 100 kHz. To maximize performance and reduce hardware complexity, we co-design hardware together with acquisition and reconstruction algorithms. The resulting AIC outperforms previously proposed solutions mainly thanks to two key features. First, we adopt a novel method to deal with saturations in the computation of CS measurements. This allows no loss in performance even when 60% of measurements saturate. Second, the system is able to adapt itself to the energy distribution of the input by exploiting the so-called rakeness to maximize the amount of information contained in the measurements. With this approach, the 16 measurement channels integrated into a single device are expected to allow the acquisition and the correct reconstruction of most biomedical signals. As a case study, measurements on real electrocardiograms (ECGs) and electromyograms (EMGs) show signals that these can be reconstructed without any noticeable degradation with a compression rate, respectively, of 8 and 10.

The influence of nitrogen and oxygen additions on the thermal characteristics of aluminium-based thin films

The ternary aluminium oxynitride (AlNxOy) system offers the possibility to obtain a wide range of properties by tailoring the ratio between pure Al, AlNx and AlOy and therefore opening a significant number of possible applications. In this work the thermal behaviour of AlNxOy thin films was analysed by modulated infrared radiometry (MIRR), taking as reference the binary AlOy and AlNx systems. MIRR is a non-contact and non-destructive thermal wave measurement technique based on the excitation, propagation and detection of temperature oscillations of very small amplitudes. The intended change of the partial pressure of the reactive gas (N2 and/or O2) influenced the target condition and hence the deposition characteristics which, altogether, affected the composition and microstructure of the films. Based on the MIRR measurements and their qualitative and quantitative interpretation, some correlations between the thermal transport properties of the films and their chemical/physical properties have been found. Furthermore, the potential of such technique applied in this oxynitride system, which present a wide range of different physical responses, is also discussed. The experimental results obtained are consistent with those reported in previous works and show a high potential to fulfil the demands needed for the possible applications of the systems studied. They are clearly indicative of an adequate thermal response if this particular thin film system is aimed to be applied in small sensor devices or in electrodes for biosignal acquisition, such as those for electroencephalography or electromyography as it is the case of the main research area that is being developed in the group.

Graphene-clad textile electrodes for electrocardiogram monitoring

Functionalized textiles and graphene are both emerging materials for wearable technologies. Here, we unite graphene with ordinary textiles and report the development of graphene-clad, conductive textile electrodes for biosignal acquisition specifically in cardiac monitoring. The proposed electrode was prepared by dipping nylon fabric in reduced graphene oxide (rGO) solution followed by a subsequent thermal treatment to allow conformal coating of conductive graphene layers around the fabric. The application of the electrode was demonstrated by successful measurements of the electrocardiogram (ECG). Performance of the textile-based electrodes were compared to the conventional silver/silver chloride (Ag/AgCl) electrodes in terms of skin-electrode impedance, ECG signal quality and noise levels. Excellent conformity and cross correlation of 97% was achieved between the signals measured with the new graphene-clad textile electrodes and conventional electrodes.

Study of the electrical behavior of nanostructured Ti–Ag thin films, prepared by Glancing Angle Deposition

Aiming at biosignal acquisition for bioelectrodes application, Ti–Ag thin films were produced by GLAD, in order to tailor their electromechanical properties. The electrical behavior of the sculptured Ti–Ag thin films was studied with increasing annealing temperatures. The results revealed a good correlation with the set of morphological features displayed. With the increase of the vapor flux angle, a more defined structure was obtained, as well as a more porous morphology, which increased the electrical resistivity of the coatings. An important point consists in the recrystallization of Ti–Ag intermetallic phases due to the temperature increase (between 558K and 773K), which resulted in a sharp decrease of the electrical resistivity values.

QR 코드를 이용한 의료정보 시스템 설계 및 구현

The new medical device technologies for bio-signal information and medical information which developed in various forms have been increasing. Information gathering techniques and the increasing of the bio-signal information device are being used as the main information of the medical service in everyday life. Hence, there is increasing in utilization of the various bio-signals, but it has a problem that does not account for security reasons. Furthermore, the medical image information and bio-signal of the patient in medical field is generated by the individual device, that make the situation cannot be managed and integrated. In order to solve that problem, in this paper we integrated the QR code signal associated with the medial image information including the finding of the doctor and the bio-signal information. bio-signal. System implementation environment for medical imaging devices and bio-signal acquisition was configured through bio-signal measurement, smart device and PC. For the ROI extraction of bio-signal and the receiving of image information that transfer from the medical equipment or bio-signal measurement, .NET Framework was used to operate the QR server module on Window Server 2008 operating system. The main function of the QR server module is to parse the DICOM file generated from the medical imaging device and extract the identified ROI information to store and manage in the database. Additionally, EMR, patient health information such as OCS, extracted ROI information needed for basic information and emergency situation is managed by QR code. QR code and ROI management and the bio-signal information file also store and manage depending on the size of receiving the bio-singnal information case with a PID (patient identification) to be used by the bio-signal device. If the receiving of information is not less than the maximum size to be converted into a QR code, the QR code and the URL information can access the bio-signal information through the server. Likewise, .Net Framework is installed to provide the information in the form of the QR code, so the client can check and find the relevant information through PC and android-based smart device. Finally, the existing medical imaging information, bio-signal information and the health information of the patient are integrated over the result of executing the application service in order to provide a medical information service which is suitable in medical field. ☞ 주제어 : QR code, Medical System, Medical image information, Bio-signal, Integration image file scheme 1 Department of Computer Engineering, Wonkwang University, Jeollabuk-do, 579-749, Korea. 2 Wonkwang University (Imaging Science Based Lung and Bone Disease Research Center), Jeollabuk-do, 579-749, Korea. * Corresponding author (scjoo@wku.ac.kr) [Received 6 February 2015, Reviewed 9 February 2015, Accepted 18 March 2015] ☆ 이 논문은 2013년도 정부(교육과학기술부) 의 재원으로 한국연 구재단의 지원을 받아 수행된 연구임 (NRF-2013R1A1A2063698). ☆ 본 논문은 2014년도 인터넷정보학회 추계학술발표대회 우수 논문 추천에 따라 확장 및 수정된 논문임. ISSN 1598-0170 (Print) ISSN 2287-1136 (Online) http://www.jksii.or.kr http://dx.doi.org/10.7472/jksii.2015.16.2.109 QR 코드를 이용한 의료정보 시스템 설계 및 구현

Cooperative dry-electrode sensors for multi-lead biopotential and bioimpedance monitoring

Cooperative sensors is a novel measurement architecture that allows the acquiring of biopotential signals on patients in a comfortable and easy-to-integrate manner. The novel sensors are defined as cooperative in the sense that at least two of them work in concert to measure a target physiological signal, such as a multi-lead electrocardiogram or a thoracic bioimpedance.This paper starts by analysing the state-of-the-art methods to simultaneously measure biopotential and bioimpedance signals, and justifies why currently (1) passive electrodes require the use of shielded or double-shielded cables, and (2) active electrodes require the use of multi-wired cabled technologies, when aiming at high quality physiological measurements.In order to overcome the limitations of the state-of-the-art, a new method for biopotential and bioimpedance measurement using the cooperative sensor is then presented. The novel architecture allows the acquisition of the aforementioned biosignals without the need of shielded or multi-wire cables by splitting the electronics into separate electronic sensors comprising each of two electrodes, one for voltage measurement and one for current injection. The sensors are directly in contact with the skin and connected together by only one unshielded wire. This new configuration requires one power supply per sensor and all sensors need to be synchronized together to allow them to work in concert.After presenting the working principle of the cooperative sensor architecture, this paper reports first experimental results on the use of the technology when applied to measuring multi-lead ECG signals on patients. Measurements performed on a healthy patient demonstrate the feasibility of using this novel cooperative sensor architecture to measure biopotential signals and compliance with common mode rejection specification accordingly to international standard (IEC 60601-2-47) has also been assessed.By reducing the need of using complex wiring setups, and by eliminating the presence of central recording devices (cooperative sensors directly sense and store the measured biosignals on the site), the depicted novel technology is a candidate to a novel generation of highly-integrated, comfortable and reliable technologies that measure physiological signals in real-life scenarios.

A programmable low power current source for bioimpedance measurement: Towards a wearable personalized health assistant.

Bioimpedance is a noninvasive measurement method that facilitates body composition analysis, besides being indicative of many other health parameters. In this work a novel programmable, low complexity, high output impedance, high voltage compliance and wideband current source for bioimpedance applications is presented. Previously, we designed, fabricated and tested in vivo a bio-patch for acquisition of multiple bio-signals. Upon integration with our previous work, this circuit is envisioned to constitute part of a personalized health assistant. Simulation at worst case corners and real operation conditions was carried out using UMC-180 nm 1 poly 6 metal CMOS process. Full duty cycle, shortened or stepped square waves can be generated. Amplitude control of 8 different current levels is supported. Frequency can be tuned up to 1 MHz and an output impedance of 2.8 MO @ 250 KHz is achieved at full current capacity. Total current consumption is comparable to the injected current, making the circuit highly efficient.

Circuit system analysis for real-time acquisition of bio-signals

Around the globe many deaths are being reported every year due to poor health monitoring system in rural areas and un-affordability by the people in the semi-rural areas. However, the evolution of bio-signal processing techniques which is a computer-based, compact, non-invasive and battery powered bio-signal monitoring solution can be reached to address this issue. An attempt has been made in this paper to analyse the developed real-time, low-cost acquisition and monitoring system in ORCAD 16.3 software. It introduces detailed analysis and explanation of the hardware circuit used to effectively acquire real-time noise-free ECG signals. Also it is adjunct to the doctors for the diagnosis purpose. The system includes instrumentation amplifier, DC restoration circuit, integrator, right leg driven amplifier and notch filter. Further it can be interfaced to a computer using sound port as a serial interface between circuit and PC for analysis in terms of features extraction. The developed circuit is compact and handy with low power consumption which realises low-cost and real-time processing.

Low-power wireless ECG acquisition and classification system for body sensor networks.

A low-power biosignal acquisition and classification system for body sensor networks is proposed. The proposed system consists of three main parts: 1) a high-pass sigma delta modulator-based biosignal processor (BSP) for signal acquisition and digitization, 2) a low-power, super-regenerative on-off keying transceiver for short-range wireless transmission, and 3) a digital signal processor (DSP) for electrocardiogram (ECG) classification. The BSP and transmitter circuits, which are the body-end circuits, can be operated for over 80 days using two 605 mAH zinc-air batteries as the power supply; the power consumption is 586.5 μW. As for the radio frequency receiver and DSP, which are the receiving-end circuits that can be integrated in smartphones or personal computers, power consumption is less than 1 mW. With a wavelet transform-based digital signal processing circuit and a diagnosis control by cardiologists, the accuracy of beat detection and ECG classification are close to 99.44% and 97.25%, respectively. All chips are fabricated in TSMC 0.18-μm standard CMOS process.