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1.
Nat Commun ; 12(1): 1973, 2021 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-33785760

RESUMO

Optical evanescent sensors can non-invasively detect unlabeled nanoscale objects in real time with unprecedented sensitivity, enabling a variety of advances in fundamental physics and biological applications. However, the intrinsic low-frequency noise therein with an approximately 1/f-shaped spectral density imposes an ultimate detection limit for monitoring many paramount processes, such as antigen-antibody reactions, cell motions and DNA hybridizations. Here, we propose and demonstrate a 1/f-noise-free optical sensor through an up-converted detection system. Experimentally, in a CMOS-compatible heterodyne interferometer, the sampling noise amplitude is suppressed by two orders of magnitude. It pushes the label-free single-nanoparticle detection limit down to the attogram level without exploiting cavity resonances, plasmonic effects, or surface charges on the analytes. Single polystyrene nanobeads and HIV-1 virus-like particles are detected as a proof-of-concept demonstration for airborne biosensing. Based on integrated waveguide arrays, our devices hold great potentials for multiplexed and rapid sensing of diverse viruses or molecules.


Assuntos
Técnicas Biossensoriais/instrumentação , Interferometria/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Técnicas Biossensoriais/métodos , Células HEK293 , Humanos , Interferometria/métodos , Limite de Detecção , Nanopartículas/química , Nanotecnologia/métodos
2.
PLoS One ; 15(12): e0243939, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33370375

RESUMO

BACKGROUND: Current cardiorespiratory monitoring equipment can cause injuries and infections in neonates with fragile skin. Impulse-radio ultra-wideband (IR-UWB) radar was recently demonstrated to be an effective contactless vital sign monitor in adults. The purpose of this study was to assess heart rates (HRs) and respiratory rates (RRs) in the neonatal intensive care unit (NICU) using IR-UWB radar and to evaluate its accuracy and reliability compared to conventional electrocardiography (ECG)/impedance pneumography (IPG). METHODS: The HR and RR were recorded in 34 neonates between 3 and 72 days of age during minimal movement (51 measurements in total) using IR-UWB radar (HRRd, RRRd) and ECG/IPG (HRECG, RRIPG) simultaneously. The radar signals were processed in real time using algorithms for neonates. Radar and ECG/IPG measurements were compared using concordance correlation coefficients (CCCs) and Bland-Altman plots. RESULTS: From the 34 neonates, 12,530 HR samples and 3,504 RR samples were measured. Both the HR and RR measured using the two methods were highly concordant when the neonates had minimal movements (CCC = 0.95 between the RRRd and RRIPG, CCC = 0.97 between the HRRd and HRECG). In the Bland-Altman plot, the mean biases were 0.17 breaths/min (95% limit of agreement [LOA] -7.0-7.3) between the RRRd and RRIPG and -0.23 bpm (95% LOA -5.3-4.8) between the HRRd and HRECG. Moreover, the agreement for the HR and RR measurements between the two modalities was consistently high regardless of neonate weight. CONCLUSIONS: A cardiorespiratory monitor using IR-UWB radar may provide accurate non-contact HR and RR estimates without wires and electrodes for neonates in the NICU.


Assuntos
Aptidão Cardiorrespiratória/fisiologia , Frequência Cardíaca/fisiologia , Monitorização Fisiológica , Taxa Respiratória/fisiologia , Eletrocardiografia/métodos , Estudos de Viabilidade , Feminino , Humanos , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Masculino , Radar , Processamento de Sinais Assistido por Computador/instrumentação
3.
Nat Commun ; 11(1): 5446, 2020 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-33116118

RESUMO

Continuous, battery-free operation of sensor nodes requires ultra-low-power sensing and data-logging techniques. Here we report that by directly coupling a sensor/transducer signal into globally asymptotically stable monotonic dynamical systems based on Fowler-Nordheim quantum tunneling, one can achieve self-powered sensing at an energy budget that is currently unachievable using conventional energy harvesting methods. The proposed device uses a differential architecture to compensate for environmental variations and the device can retain sensed information for durations ranging from hours to days. With a theoretical operating energy budget less than 10 attojoules, we demonstrate that when integrated with a miniature piezoelectric transducer the proposed sensor-data-logger can measure cumulative "action" due to ambient mechanical acceleration without any additional external power.


Assuntos
Engenharia Biomédica/instrumentação , Coleta de Dados/instrumentação , Fontes de Energia Elétrica , Transdutores , Aceleração , Fontes de Energia Bioelétrica , Engenharia Biomédica/estatística & dados numéricos , Coleta de Dados/estatística & dados numéricos , Eletrônica/instrumentação , Eletrônica/estatística & dados numéricos , Desenho de Equipamento , Fenômenos Mecânicos , Processamento de Sinais Assistido por Computador/instrumentação
4.
Nat Commun ; 11(1): 4234, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32843643

RESUMO

Brain-machine interfaces are promising tools to restore lost motor functions and probe brain functional mechanisms. As the number of recording electrodes has been exponentially rising, the signal processing capability of brain-machine interfaces is falling behind. One of the key bottlenecks is that they adopt conventional von Neumann architecture with digital computation that is fundamentally different from the working principle of human brain. In this work, we present a memristor-based neural signal analysis system, where the bio-plausible characteristics of memristors are utilized to analyze signals in the analog domain with high efficiency. As a proof-of-concept demonstration, memristor arrays are used to implement the filtering and identification of epilepsy-related neural signals, achieving a high accuracy of 93.46%. Remarkably, our memristor-based system shows nearly 400× improvements in the power efficiency compared to state-of-the-art complementary metal-oxide-semiconductor systems. This work demonstrates the feasibility of using memristors for high-performance neural signal analysis in next-generation brain-machine interfaces.


Assuntos
Interfaces Cérebro-Computador , Redes Neurais de Computação , Processamento de Sinais Assistido por Computador/instrumentação , Encéfalo/fisiologia , Computadores Analógicos , Sinapses Elétricas/fisiologia , Epilepsia/fisiopatologia , Humanos , Modelos Neurológicos , Transistores Eletrônicos
5.
Nat Commun ; 11(1): 3278, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32606311

RESUMO

On-implant spike sorting methods employ static feature extraction/selection techniques to minimize the hardware cost. Here we propose a novel framework for real-time spike sorting based on dynamic selection of features. We select salient features that maximize the geometric-mean of between-class distances as well as the associated homogeneity index effectively to best discriminate spikes for classification. Wave-shape classification is performed based on a multi-label window discrimination approach. An external module calculates the salient features and discrimination windows through optimizing a replica of the on-implant operation, and then configures the on-implant spike sorter for real-time online operation. Hardware implementation of the on-implant online spike sorter for 512 channels of concurrent extra-cellular neural signals is reported, with an average classification accuracy of ~88%. Compared with other similar methods, our method shows reduction in classification error by a factor of ~2, and also reduction in the required memory space by a factor of ~5.


Assuntos
Potenciais de Ação/fisiologia , Algoritmos , Encéfalo/fisiologia , Modelos Neurológicos , Neurônios/fisiologia , Processamento de Sinais Assistido por Computador/instrumentação , Encéfalo/citologia , Eletrofisiologia/instrumentação , Eletrofisiologia/métodos , Humanos , Neuroestimuladores Implantáveis
7.
Sensors (Basel) ; 20(5)2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32131467

RESUMO

Changes in a certain parameter are often a few magnitudes smaller than the base value of the parameter, specifying significant requirements for the dynamic range and noise levels of the measurement system. In case of electrical bioimpedance acquisition, the variations can be 1000 times smaller than the entire measured value. Synchronous or lock-in measurement of these variations is discussed in the current paper, and novel measurement solutions are presented. Proposed methods are simple and robust when compared to other applicable solutions. A common feature shared by all members of the group of the proposed solutions is differentiation. It is achieved by calculating the differences between synchronously acquired consecutive samples, with lock-in integration and analog differentiation. All these methods enable inherent separation of variations from the static component of the signal. The variable component of the bioimpedance can, thus, be acquired using the full available dynamic range of the apparatus for its detection. Additive disturbing signals and omnipresent wideband noise are considered and the method for their reduction is proposed.


Assuntos
Processamento de Sinais Assistido por Computador/instrumentação , Impedância Elétrica , Eletrodos , Meio Ambiente , Humanos
8.
JCO Clin Cancer Inform ; 4: 221-233, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32155093

RESUMO

PURPOSE: Deep learning (DL), a class of approaches involving self-learned discriminative features, is increasingly being applied to digital pathology (DP) images for tasks such as disease identification and segmentation of tissue primitives (eg, nuclei, glands, lymphocytes). One application of DP is in telepathology, which involves digitally transmitting DP slides over the Internet for secondary diagnosis by an expert at a remote location. Unfortunately, the places benefiting most from telepathology often have poor Internet quality, resulting in prohibitive transmission times of DP images. Image compression may help, but the degree to which image compression affects performance of DL algorithms has been largely unexplored. METHODS: We investigated the effects of image compression on the performance of DL strategies in the context of 3 representative use cases involving segmentation of nuclei (n = 137), segmentation of lymph node metastasis (n = 380), and lymphocyte detection (n = 100). For each use case, test images at various levels of compression (JPEG compression quality score ranging from 1-100 and JPEG2000 compression peak signal-to-noise ratio ranging from 18-100 dB) were evaluated by a DL classifier. Performance metrics including F1 score and area under the receiver operating characteristic curve were computed at the various compression levels. RESULTS: Our results suggest that DP images can be compressed by 85% while still maintaining the performance of the DL algorithms at 95% of what is achievable without any compression. Interestingly, the maximum compression level sustainable by DL algorithms is similar to where pathologists also reported difficulties in providing accurate interpretations. CONCLUSION: Our findings seem to suggest that in low-resource settings, DP images can be significantly compressed before transmission for DL-based telepathology applications.


Assuntos
Compressão de Dados/métodos , Aprendizado Profundo/normas , Interpretação de Imagem Assistida por Computador/métodos , Neoplasias/patologia , Patologia Clínica/normas , Processamento de Sinais Assistido por Computador/instrumentação , Telepatologia/normas , Algoritmos , Benchmarking/normas , Humanos , Neoplasias/terapia , Variações Dependentes do Observador , Controle de Qualidade , Curva ROC
9.
Sensors (Basel) ; 20(3)2020 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-32024267

RESUMO

This paper covers a brief review of both the advantages and disadvantages of the implementation of various smoothing filters in the analysis of electroencephalography (EEG) data for the purpose of potential medical diagnostics. The EEG data are very prone to the occurrence of various internal and external artifacts and signal distortions. In this paper, three types of smoothing filters were compared: smooth filter, median filter and Savitzky-Golay filter. The authors of this paper compared those filters and proved their usefulness, as they made the analyzed data more legible for diagnostic purposes. The obtained results were promising, however, the studies on finding perfect filtering methods are still in progress.


Assuntos
Encéfalo/diagnóstico por imagem , Eletroencefalografia/métodos , Processamento de Sinais Assistido por Computador/instrumentação , Adulto , Algoritmos , Artefatos , Encéfalo/fisiologia , Feminino , Filtração , Humanos , Masculino , Adulto Jovem
10.
Sensors (Basel) ; 20(3)2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32019228

RESUMO

Photoacoustic (PA) imaging is a hybrid imaging technique that can provide both structural and functional information of biological tissues. Due to limited permissible laser energy deposited on tissues, highly sensitive PA imaging is required. Here, we developed a 20 MHz lead zirconium titanate (PZT) transducer (1.5 mm × 3 mm) with front-end amplifier circuits for local signal processing to achieve sensitivity enhanced PA imaging. The electrical and acoustic performance was characterized. Experiments on phantoms and chicken breast tissue were conducted to validate the imaging performance. The fabricated prototype shows a bandwidth of 63% and achieves a noise equivalent pressure (NEP) of 0.24 mPa/√Hz and a receiving sensitivity of 62.1 µV/Pa at 20 MHz without degradation of the bandwidth. PA imaging of wire phantoms demonstrates that the prototype is capable of improving the detection sensitivity by 10 dB compared with the traditional transducer without integrated amplifier. In addition, in vitro experiments on chicken breast tissue show that structures could be imaged with enhanced contrast using the prototype and the imaging depth range was improved by 1 mm. These results demonstrate that the transducer with an integrated front-end amplifier enables highly sensitive PA imaging with improved penetration depth. The proposed method holds the potential for visualization of deep tissue structures and enhanced detection of weak physiological changes.


Assuntos
Técnicas Fotoacústicas , Processamento de Sinais Assistido por Computador/instrumentação , Ultrassonografia/métodos , Amplificadores Eletrônicos , Desenho de Equipamento , Humanos , Aumento da Imagem/métodos , Chumbo/química , Imagens de Fantasmas , Análise Espectral , Titânio/química , Transdutores , Zircônio/química
11.
Sensors (Basel) ; 20(1)2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31935909

RESUMO

In order to develop more precise and functional affective applications, it is necessary to achieve a balance between the psychology and the engineering applied to emotions. Signals from the central and peripheral nervous systems have been used for emotion recognition purposes, however, their operation and the relationship between them remains unknown. In this context, in the present work, we have tried to approach the study of the psychobiology of both systems in order to generate a computational model for the recognition of emotions in the dimension of valence. To this end, the electroencephalography (EEG) signal, electrocardiography (ECG) signal and skin temperature of 24 subjects have been studied. Each methodology has been evaluated individually, finding characteristic patterns of positive and negative emotions in each of them. After feature selection of each methodology, the results of the classification showed that, although the classification of emotions is possible at both central and peripheral levels, the multimodal approach did not improve the results obtained through the EEG alone. In addition, differences have been observed between cerebral and peripheral responses in the processing of emotions by separating the sample by sex; though, the differences between men and women were only notable at the peripheral nervous system level.


Assuntos
Encéfalo/fisiologia , Emoções/fisiologia , Sistema Nervoso Periférico/fisiologia , Reconhecimento Psicológico/fisiologia , Adulto , Algoritmos , Eletrocardiografia/instrumentação , Eletroencefalografia/instrumentação , Feminino , Humanos , Masculino , Caracteres Sexuais , Processamento de Sinais Assistido por Computador/instrumentação , Adulto Jovem
12.
Asian Pac J Cancer Prev ; 21(1): 179-183, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31983182

RESUMO

OBJECTIVE: The survival rates of breast cancer are increasing as screening and diagnosis improve. The removal of noise is revealed to be a significant step for automatic - computer aided detection (CAD) of microcalcification in digital mammography. METHODS: In this paper, a combined approach for eradicating impulse noise from digital mammograms is proposed. The process is achieved in two stages, detection of noise followed by filtering of noise. The detection of noise is carried out by using Modified Robust Outlyingness Ratio (mROR) trailed by an extended NL (Non-Local)-means filter for filtering mechanism. RESULTS: According to the value of mROR, all pixels in mammogram images are divided into four distinct groups. In each cluster, many decision rules are then applied for detecting the impulse noise. Filtering is done with NL-means filter by providing a reference mammogram image. CONCLUSION: The comparative analysis and evaluated results are compared with some existing filters which indicate that the proposed structure outperforms the analysed result of others.


Assuntos
Algoritmos , Neoplasias da Mama/patologia , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Mamografia/instrumentação , Mamografia/métodos , Processamento de Sinais Assistido por Computador/instrumentação , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Prognóstico , Razão Sinal-Ruído
13.
Sensors (Basel) ; 20(3)2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31979184

RESUMO

In this paper we proposed a wearable electrocardiogram (ECG) telemonitoring system for atrial fibrillation (AF) detection based on a smartphone and cloud computing. A wearable ECG patch was designed to collect ECG signals and send the signals to an Android smartphone via Bluetooth. An Android APP was developed to display the ECG waveforms in real time and transmit every 30 s ECG data to a remote cloud server. A machine learning (CatBoost)-based ECG classification method was proposed to detect AF in the cloud server. In case of detected AF, the cloud server pushed the ECG data and classification results to the web browser of a doctor. Finally, the Android APP displayed the doctor's diagnosis for the ECG signals. Experimental results showed the proposed CatBoost classifier trained with 17 selected features achieved an overall F1 score of 0.92 on the test set (n = 7,270). The proposed wearable ECG monitoring system may potentially be useful for long-term ECG telemonitoring for AF detection.


Assuntos
Fibrilação Atrial/diagnóstico , Eletrocardiografia Ambulatorial/instrumentação , Eletrocardiografia Ambulatorial/métodos , Eletrocardiografia/instrumentação , Eletrocardiografia/métodos , Algoritmos , Computação em Nuvem , Humanos , Aprendizado de Máquina , Processamento de Sinais Assistido por Computador/instrumentação , Smartphone , Dispositivos Eletrônicos Vestíveis , Tecnologia sem Fio/instrumentação
14.
Sci Rep ; 10(1): 415, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31942039

RESUMO

Non-invasive, contrast-free microvascular imaging of human thyroids can be potentially beneficial in reducing the large number of benign biopsies of suspicious nodules. However, motion incurred by thyroid due to its proximity to the pulsating carotid artery significantly impacts the visualization of blood flow in small vessels. Singular value based spatiotemporal clutter filtering (SVD-STF) improves the performance of tissue rejection in the presence of motion. However, despite effective clutter filtering, motion in thyroid imaging can impact coherent integration of the Doppler ensemble and degrade the visualization of the underlying vasculature. Recently studies have demonstrated that motion correction using 2D normalized cross-correlation based speckle tracking can address this issue, however, only in-plane motion can be tracked and corrected. Given the natural anatomical orientation of the rigid trachea, thyroid and the pulsating carotid artery, we hypothesize that imaging of thyroid microvessels may be more reliable in the longitudinal view than in the transverse. Specifically, distal presence of rigid trachea can limit out-of-plane motion in the longitudinal view. We tested this hypothesis on 48 acquisitions obtained from 24 thyroid patients having at least one suspicious nodule. In each patient, ultrasound images of the thyroid were acquired in both longitudinal and transverse views. Compounded plane-wave imaging was used to acquire the ultrasound images at high frame-rate, which is important for contrast-free small vessel blood flow imaging. Thyroid motion was tracked using 2D normalized cross-correlation based speckle tracking. Tissue clutter was rejected using singular value decomposition based spatiotemporal clutter filtering. The clutter-filtered Doppler ensemble was motion corrected prior to slow-time power Doppler integration. Signal-to-noise and contrast-to-noise ratios were computed to assess the improvement in quality of the power Doppler images. Out-of-plane motion was detected by estimating normalized ensemble cross-correlation coefficient. The results demonstrated that motion associated with the thyroid due to the carotid artery was primarily in the lateral direction, which could be estimated and corrected using 2D speckle tracking. However, the motion in the transverse view displayed increased speckle decorrelation. The average ensemble cross-correlation coefficient of the thyroid ultrasound images were significantly higher (p < 0.05) in the longitudinal view than in the transverse view. The largest improvement in SNR and CNR of the estimated PD images upon motion correction was observed in the longitudinal view (12.95 ± 3.76 dB and 16.48 ± 4.6 dB) than in the transverse view (3.72 ± 0.894 dB and 6.217 ± 1.689 dB). These preliminary results show that motion encountered by the thyroid due to carotid pulsations can be effectively tracked and corrected in the longitudinal view relative to transverse, which is important for reliably visualizing the underlying blood flow.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Microvasos/diagnóstico por imagem , Processamento de Sinais Assistido por Computador/instrumentação , Glândula Tireoide/diagnóstico por imagem , Ultrassonografia/métodos , Feminino , Humanos , Masculino , Projetos Piloto
15.
Sensors (Basel) ; 20(2)2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31968532

RESUMO

We present an eating detection algorithm for wearable sensors based on first detecting chewing cycles and subsequently estimating eating phases. We term the corresponding algorithm class as a bottom-up approach. We evaluated the algorithm using electromyographic (EMG) recordings from diet-monitoring eyeglasses in free-living and compared the bottom-up approach against two top-down algorithms. We show that the F1 score was no longer the primary relevant evaluation metric when retrieval rates exceeded approx. 90%. Instead, detection timing errors provided more important insight into detection performance. In 122 hours of free-living EMG data from 10 participants, a total of 44 eating occasions were detected, with a maximum F1 score of 99.2%. Average detection timing errors of the bottom-up algorithm were 2.4 ± 0.4 s and 4.3 ± 0.4 s for the start and end of eating occasions, respectively. Our bottom-up algorithm has the potential to work with different wearable sensors that provide chewing cycle data. We suggest that the research community report timing errors (e.g., using the metrics described in this work).


Assuntos
Mastigação/fisiologia , Monitorização Fisiológica/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Óculos Inteligentes , Adulto , Algoritmos , Dieta , Eletromiografia , Feminino , Humanos , Masculino , Monitorização Fisiológica/métodos , Músculo Temporal/fisiologia
17.
IEEE J Biomed Health Inform ; 24(1): 226-234, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30794193

RESUMO

OBJECTIVE: This paper presents an integrated device, based on smart glasses, for the pattern-reversal visual evoked potential (PR-VEP) clinical test. METHODS: Smart glasses are used to generate the checkerboard changing pattern, with its related red fixation point through an Android application. Electroencephalographic signals, for monitoring the stimulus generated by PR-VEP, were amplified close to the scalp and then transmitted wirelessly to a PC. A MATLAB real-time algorithm processed the incoming signals to extract the final PR-VEP signal. METHODS: In total, 40 eyes (from 20 subjects, 12 males and 8 females between 24 and 28 years old) were tested and results were compared, with a commercial device for VEP clinical exam, to test the reproducibility and the efficacy of the proposed solution. RESULTS: PR-VEPs generated by smart glasses showed typical triphasic waveforms: We observed promising results and components in moderate agreement with those obtained using commercial PR-VEP recorder, with potential for improvements after further refinement works. SIGNIFICANCE: The proposed device leads the way for a portable and low-cost solution.


Assuntos
Potenciais Evocados Visuais/fisiologia , Processamento de Sinais Assistido por Computador/instrumentação , Óculos Inteligentes , Adulto , Algoritmos , Eletroencefalografia , Desenho de Equipamento , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Adulto Jovem
18.
IEEE J Biomed Health Inform ; 24(1): 120-130, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30843855

RESUMO

OBJECTIVE: The complex nature of Parkinson's disease (PD) makes difficult to rate its severity, mainly based on the visual inspection of motor impairments. Wearable sensors have been demonstrated to help overcoming such a difficulty, by providing objective measures of motor abnormalities. However, up to now, those sensors have been used on advanced PD patients with evident motor impairment. As a novelty, here we report the impact of wearable sensors in the evaluation of motor abnormalities in newly diagnosed, untreated, namely de novo, patients. METHODS: A network of wearable sensors was used to measure motor capabilities, in 30 de novo PD patients and 30 healthy subjects, while performing five motor tasks. Measurement data were used to determine motor features useful to highlight impairments and were compared with the corresponding clinical scores. Three classifiers were used to differentiate PD from healthy subjects. RESULTS: Motor features gathered from wearable sensors showed a high degree of significance in discriminating the early untreated de novo PD patients from the healthy subjects, with 95% accuracy. The rates of severity obtained from the measured features are partially in agreement with the clinical scores, with some highlighted, though justified, exceptions. CONCLUSION: Our findings support the feasibility of adopting wearable sensors in the detection of motor anomalies in early, untreated, PD patients. SIGNIFICANCE: This work demonstrates that subtle motor impairments, occurring in de novo patients, can be evidenced by means of wearable sensors, providing clinicians with instrumental tools as suitable supports for early diagnosis, and subsequent management.


Assuntos
Aprendizado de Máquina , Doença de Parkinson , Dispositivos Eletrônicos Vestíveis , Acelerometria/instrumentação , Adulto , Idoso , Idoso de 80 Anos ou mais , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica/instrumentação , Movimento/fisiologia , Doença de Parkinson/classificação , Doença de Parkinson/diagnóstico , Doença de Parkinson/fisiopatologia , Processamento de Sinais Assistido por Computador/instrumentação
19.
IEEE Trans Biomed Circuits Syst ; 14(1): 75-90, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31831432

RESUMO

A novel phase-canceling demodulation scheme to improve the linearity of a self-injection-locked (SIL) ultrasonic radar is proposed with the goal of solving the null detection problem and accurately sensing large displacements of a moving target. A proportional-integral (PI) controller regulates the phase of the injection signal and cancels the Doppler phase shift by tuning a delay in the received echo signal, and this tunable delay serves as the radar output, which is linearly proportional to the displacement of the target. Without assuming weak injection, the frequency and phase equations for an SIL oscillator are derived, supporting the construction of a plant model and the design of a PI controller. Also, a new ultrasonic radar equation is presented for estimating the radar detection range. The SIL radar with phase regulation is operated in its anti-phase injection mode for better performance. The proposed design is implemented on an FPGA to make a 40 kHz continuous-wave ultrasonic radar. The maximum detectable peak-to-peak motion is up to 120 mm (approximately 14 wavelengths of displacement), with a total harmonic distortion as low as 2.3% for the detection of 1 Hz harmonic motion. The radar is used to detect the human chest movement for non-contact monitoring of the respiratory rate and heart rate. Due to the high linearity and sensitivity, the radar is capable of faithfully detecting the relatively large involuntary body movements and lung movements while still preserving the weak heartbeat rhythm buried in them, with the average error of measured heart rates less than 1 BPM.


Assuntos
Testes de Função Cardíaca/instrumentação , Testes de Função Respiratória/instrumentação , Ultrassonografia Doppler/instrumentação , Algoritmos , Efeito Doppler , Desenho de Equipamento , Humanos , Radar , Processamento de Sinais Assistido por Computador/instrumentação
20.
IEEE J Biomed Health Inform ; 24(1): 92-100, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30668508

RESUMO

Surgery is a particularly potent stressor and the detrimental effects of stress on people undergoing any surgery is indisputable. When left unchecked, the pre-surgery stress adversely impacts people's physical and psychological well-being, and may even evolve into severe pathological states. Therefore, it is essential to identify levels of preoperative stress in surgical patients. This paper focuses on developing an automatic pre-surgery stress detection scheme based on electrodermal activity (EDA). The measurement set up involves a wrist wearable that monitors EDA of a subject continuously in the most non-invasive and unobtrusive manner. Data were collected from 41 subjects [17 females and 24 males, age: 54.8 ± 16.8 years (mean ± SD)], who subsequently underwent different surgical procedures at the Sri Ramakrishna Hospital, Coimbatore, India. A supervised machine learning algorithm that detects motion artifacts in the recorded EDA data was developed. It yielded an accuracy of 97.83% on a new user dataset. The clean EDA data were further analyzed to determine low, moderate, and high levels of stress. A novel localized supervised learning scheme based on the adaptive partitioning of the dataset was adopted for stress detection. Consequently, the interindividual variability in the EDA due to person-specific factors such as the sweat gland density and skin thickness, which may lead to erroneous classification, could be eliminated. The scheme yielded a classification accuracy of 85.06% on a new user dataset and proved to be more effective than the general supervised classification model.


Assuntos
Resposta Galvânica da Pele/fisiologia , Cuidados Pré-Operatórios , Estresse Psicológico/diagnóstico , Dispositivos Eletrônicos Vestíveis , Punho/fisiologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cuidados Pré-Operatórios/instrumentação , Cuidados Pré-Operatórios/métodos , Processamento de Sinais Assistido por Computador/instrumentação , Estresse Psicológico/fisiopatologia
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