Ron E. Banister

A fall detection study on the sensors placement location and a rule-based multi-thresholds algorithm using both accelerometer and gyroscopes

Falls are dangerous among the elderly population and are a major health concern. Many investigators have reported the use of accelerometers for fall detection. In addition, the use of miniature gyroscopes has also been reported to be able to detect falls, but the effects of sensor placement on the back of a person have not been studied thoroughly. In this paper we present a simple solution for effective fall detection using both an accelerometer and two gyroscopes placed, as a single unit, on three different positions along the thoracic vertebrae (i.e., T-4, T-7, and T-10). Results indicated that T-10 was not a good location for the gyroscope placement for fall detection. However, both T-4 and T-7 were suitable, with the results for T-4 being slightly better. Using a simple rule-based multi-thresholds algorithm that utilizes the recorded resultant gravitational acceleration, angular change, angular velocity, and angular acceleration, we were able to successfully detect all 60 falls and differentiate between falls and activities of daily living (ADL) with no false positives on young volunteers. More testing data is needed, especially for backward falls, to test the robustness of our simple algorithm and to improve the sensor portability for future trial studies on geriatric populations.

Chronic Pain and Ultrarapid Opioid Detoxification

Abstract:  Availability of opiate substances through physicians and on the street has led to a rise in dependence and in addiction resulting in countless numbers of people hooked on these drugs. Long‐term use of these agents results in reduction of endogenous supply of opiate replaced by these exogenous compounds. A technique known as Ultrarapid Detoxification (UROD) has been developed and appears more promising than conventional modalities. UROD has been modified over 3 decades resulting in a safe and an effective general anesthetic that results in hemodynamically stable withdrawal without manifestation of central nervous system hyperarousal. A cornerstone of this technique involves clonidine, which stimulates reuptake of catecholamines and allows for large doses of opioid antagonist to be delivered without significant changes in heart rate or blood pressure, displacing the opiate. Though techniques vary from center to center, safety should be paramount with the technique performed in an intensive care unit with trained professional anesthesiologists. Psychosocial issues should be evaluated by a trained addictionalist and most people will succeed from the UROD procedure without experiencing the horrible withdrawal syndrome. Patients must have realistic goals and be prepared to deal with psychosocial issues post‐procedure.

Changes in compliance predict pulmonary morbidity in patients undergoing abdominal plication.

The incidence and severity of the effects of pulmonary compliance changes were investigated in patients undergoing abdominal plication surgery. A total of 20 healthy adults scheduled for abdominal plication surgery who had no significant history of pulmonary disease and 20 adults scheduled for nonabdominal, nonthoracic surgery (control group) underwent general endotracheal anesthesia; neuromuscular blockade was confirmed with electrical twitch monitoring. Before abdominal plication, the mean airway compliance was measured under total neuromuscular blockade at 33.4 +/- 2.1 ml/cm water, which was not significant when compared with control patient values. After abdominal plication was performed, the mean airway compliance was remeasured under total neuromuscular blockade; it was significantly decreased at 24.0 +/- 1.8 ml/cm water when compared with values for control patients (32.6 +/- 1.6 ml/cm) and with preplication values. Patients with airway compliance changes of less than 4 ml/cm water (when compared with preplication pulmonary mechanics) had far less incidence of atelectasis, requirements for supplemental oxygen at 24 hours or longer, or hypoxia when compared with patients with compliance changes of greater than 4 ml/cm water. Patients with compliance changes greater than 9 ml/cm water had the highest incidence of pulmonary morbidity. These data suggest that significant changes in pulmonary compliance occur after abdominal plication and that these airway compliance changes are associated with a clinically increased incidence of pulmonary morbidity in the postoperative period.

Robust phased array non-contact vital signs monitoring in an office cubicle setting

Doppler-based non-contact vital signs (NCVS) sensor systems can monitor the heart and respiration rates without touching the patient, but the accuracy of the NCVS sensing can be degraded considerably by background clutters and movements artifacts from the monitored subject or other motions in the measurement environment. We have, therefore, developed a high directivity phased-array antenna NCVS system that can significantly increase the sensing accuracy and the monitoring range in a typical office cubicle setting. Depending on the position of the beam spot illuminated on the chest, our custom-made beam-steerable phased array NCVS system at 2.4GHz has demonstrated the accuracy of the heart rate monitoring to be within +/- 2 bpm (beat-per-minute) for 92.5%-99.2% of the time at 0.75m. As the monitoring range is extended to 1-1.5m with beam directly illuminating on the center of the chest, the heart rate monitoring accuracy remains within +/- 5 bpm above 78% of time. With more improvement, this phased array NCVS system should benefit patients considerably for telemedicine and remote monitoring, as the patients vital signs can be monitored comfortably and continuously in both home and office settings, eventually capable of detecting potential sleep apnea and other respiratory or cardiovascular symptoms in real-time.

A phased array non-contact vital signs sensor with automatic beam steering

Doppler-based non-contact vital signs (NCVS) sensor systems have the ability to monitor heart and respiration rates of patients without physical contacts. Because the accuracy of a NCVS sensor can deteriorate quickly in a noisy or cluttered environment, and that patients confined on their beds have different physical sizes and microwave signatures and will still move naturally (though not frequently), continuous NCVS monitoring that can work well for all individuals is very difficult. Therefore, we have developed a highly directive phased-array antenna NCVS system that can perform automatic electronic beam steering for continuous NCVS monitoring with considerably improved monitoring accuracy over that obtained from the Doppler radar with a fixed beam. Our NCVS system includes an automatic beam steering algorithm, and has achieved heart rate measurement accuracy of nearly 95% within 5 beat-per-minute (BPM) vs. reference at our engineering lab.

Accurate and continuous non-contact vital signs monitoring using phased array antennas in a clutter-free anechoic chamber

Continuous and accurate monitoring of human vital signs is an important part of the healthcare industry, as it is the basic means by which the clinicians can determine the instantaneous status of their patients. Doppler-based noncontact vital signs (NCVS) sensor systems can monitor the heart and respiration rates without touching the patient, but it has been observed that that the accuracy of these NCVS sensors can be diminished by reflections from background clutters in the measurement environment, and that high directivity antennas can increase the sensing accuracy. Therefore, this work explores a NCVS sensor with continuous data taken inside an anechoic chamber where the background cluttering is negligible. In addition, a high directivity custom-made beam-steerable phased array antenna system is used to improve the performance and functionality of the 2.4GHz NCVS sensor we have built. We believe this work is the 1st systematic study using Doppler-based phased array systems for NCVS sensing performed in a clutter-free anechoic chamber.

A 2.4GHz non-contact biosensor system for continuous vital-signs monitoring

A non-contact vital-signs monitoring sensor system has been designed and tested. The system is assembled using two antennas instead of using one antenna and a circulator to achieve improved data accuracy with reduced DC offset. The system has been realized using a custom-designed analog baseband signal processing PCB that successfully replaces bulky baseband electronic blocks for system miniaturization. The sensor system was implemented in both single-channel and quadrature receiver configurations with the received signal being demodulated using several different algorithms. The vital-signs data extracted from a quadrature receiver with arctangent demodulation and autocorrelation method is found to be most accurate and reliable, achieving a mean error of +/- 1 beats/min vs. the reference heartbeat signal.

MEMS-based sensing and algorithm development for fall detection and gait analysis

Falls by the elderly are highly detrimental to health, frequently resulting in injury, high medical costs, and even death. Using a MEMS-based sensing system, algorithms are being developed for detecting falls and monitoring the gait of elderly and disabled persons. In this study, wireless sensors utilize Zigbee protocols were incorporated into planar shoe insoles and a waist mounted device. The insole contains four sensors to measure pressure applied by the foot. A MEMS based tri-axial accelerometer is embedded in the insert and a second one is utilized by the waist mounted device. The primary fall detection algorithm is derived from the waist accelerometer. The differential acceleration is calculated from samples received in 1.5s time intervals. This differential acceleration provides the quantification via an energy index. From this index one may ascertain different gait and identify fall events. Once a pre-determined index threshold is exceeded, the algorithm will classify an event as a fall or a stumble. The secondary algorithm is derived from frequency analysis techniques. The analysis consists of wavelet transforms conducted on the waist accelerometer data. The insole pressure data is then used to underline discrepancies in the transforms, providing more accurate data for classifying gait and/or detecting falls. The range of the transform amplitude in the fourth iteration of a Daubechies-6 transform was found sufficient to detect and classify fall events.

Long-term vital sign measurement using a non-contact vital sign sensor inside an office cubicle setting

Heart and respiration rates can be wirelessly measured by extracting the phase shift caused by the periodic displacement of a patients chest wall. We have developed a phased-array Doppler-based non-contact vital sign (NCVS) sensor capable of long-term vital signs monitoring using an automatic patient tracking and movement detection algorithm. Our NCVS sensor achieves non-contact heart rate monitoring with accuracies of over 90% (i.e, within ±5 Beats-Per-Minute vs. a reference sensor) across a large number of data points collected over various days of the week inside a typical office cubicle setting at a distance of 1.5 meters.

Non-Contact Sensor for Long-Term Continuous Vital Signs Monitoring: A Review on Intelligent Phased-Array Doppler Sensor Design

It has been the dream of many scientists and engineers to realize a non-contact remote sensing system that can perform continuous, accurate and long-term monitoring of human vital signs as we have seen in many Sci-Fi movies. Having an intelligible sensor system that can measure and record key vital signs (such as heart rates and respiration rates) remotely and continuously without touching the patients, for example, can be an invaluable tool for physicians who need to make rapid life-and-death decisions. Such a sensor system can also effectively help physicians and patients making better informed decisions when patients’ long-term vital signs data is available. Therefore, there has been a lot of research activities on developing a non-contact sensor system that can monitor a patient’s vital signs and quickly transmit the information to healthcare professionals. Doppler-based radio-frequency (RF) non-contact vital signs (NCVS) monitoring system are particularly attractive for long term vital signs monitoring because there are no wires, electrodes, wearable devices, nor any contact-based sensors involved so the subjects may not be even aware of the ubiquitous monitoring. In this paper, we will provide a brief review on some latest development on NCVS sensors and compare them against a few novel and intelligent phased-array Doppler-based RF NCVS biosensors we have built in our labs. Some of our NCVS sensor tests were performed within a clutter-free anechoic chamber to mitigate the environmental clutters, while most tests were conducted within the typical Herman-Miller type office cubicle setting to mimic a more practical monitoring environment. Additionally, we will show the measurement data to demonstrate the feasibility of long-term NCVS monitoring. The measured data strongly suggests that our latest phased array NCVS system should be able to perform long-term vital signs monitoring intelligently and robustly, especially for situations where the subject is sleeping without hectic movements nearby.