Analysis of Spectral Estimation Algorithms for Accurate Heart Rate and Respiration Rate Estimation Using an Ultra-Wideband Radar Sensor.

Non-contact vital sign monitoring has been an important research topic recently due to the ability to monitor patients for an extended period especially during sleep without requiring uncomfortable attachments. Radar is a popular sensor for vital sign monitoring research. Various algorithms have been proposed for estimating respiration rate and heart rate from the radar data. But many algorithms rely on Fast Fourier Transform (FFT) to convert time domain signal to the frequency domain and estimate vital signs, despite FFT having limitation of frequency resolution being inverse of the time interval of data sample. However, there are other spectral estimation algorithms, which have not been much researched into the suitability of vital sign estimation using radar signals. In this paper, we compared eight different types of spectral estimation algorithms, including FFT, for respiration rate and heart rate estimation of stationary subjects in a controlled environment. The evaluation is based on extensive data consisting of different stationary subject positions. Considering the results, the eligibility of algorithms other than FFT for respiration rate and heart rate estimation is demonstrated. Using this work, researchers can get an overview on which algorithm is suitable for their work without the need to review individual algorithms separately.

Flexible Forearm Triboelectric Sensors for Parkinson's Disease Diagnosing and Monitoring.

Existing approaches that assess and monitor the severity of Parkinson's Disease (PD) focus on the integration of wearable devices based on inertial sensors (accelerometers, gyroscopes) and electromyographic (EMG) transducers. Nevertheless, some of these sensors are bulky and lack comfortability. This manuscript presents triboelectric nanogenerators (TENGs) as an alternative stretchable sensor solution enabling PD monitoring systems. The prototype has been developed using a triboelectric sensor based on Ecoflex™ and PEDOT:PSS that is placed on the forearm. The movement of the skin above the forearm muscles and tendons correlates with the extension and flexion of fingers and hands. This way, the small gap of 0.5 cm between the polymer layers is displaced, generating voltage due to the triboelectric contact. Signals from preliminary experiments can discriminate different dynamics of emulated tremor and bradykinesia in hands and fingers. A modified version of the TS is integrated with a printed circuit board (PCB) in a single package with signal conditioning and wireless data transmission. The sensor platforms have demonstrated a good sensitivity to PD symptoms like bradykinesia and tremor based on the Unified Parkinson's Disease Rating Scale (MDS:UPDRS).

Next-generation ingestible devices: sensing, locomotion and navigation.

There is significant interest in exploring the human body's internal activities and measuring important parameters to understand, treat and diagnose the digestive system environment and related diseases. Wireless capsule endoscopy (WCE) is widely used for gastrointestinal (GI) tract exploration due to its effectiveness as it provides no pain and is totally tolerated by the patient. Current ingestible sensing technology provides a valuable diagnostic tool to establish a platform for monitoring the physiological and biological activities inside the human body. It is also used for visualizing the GI tract to observe abnormalities by recording the internal cavity while moving. However, the capsule endoscopy is still passive, and there is no successful locomotion method to control its mobility through the whole GI tract. Drug delivery, localization of abnormalities, cost reduction and time consumption are improvements that can be gained from having active ingestible WCEs. In this article, the current technological developments of ingestible devices including sensing, locomotion and navigation are discussed and compared. The main features required to implement next-generation active WCEs are explored. The methods are evaluated in terms of the most important features such as safety, velocity, complexity of design, control, and power consumption.

Chest-based Real-Time Pulse and Respiration Monitoring Based on Bio-Impedance.

Pulse wave and respiration are two important vital signals in diagnosing and treating diseases. In this paper, we investigated a Bio-impedance (BImp) based respiration and pulse wave monitoring system. The BImp signal is successfully extracted from a wearable device placed on the shoulder. Using the rate calculation algorithm, heart rate (HR), and respiration rate (RR) values are extracted accurately. The data is collected during different steps of breathing including slow, fast, deep, hold, and normal from 10 volunteers. The accuracy of HR results is compared to that of extracted from PPG with considering ECG based HR as reference. The extracted RR values are investigated against TCo2 sensor's output. The estimation of both RR and HR extracted from the BImp signal has higher accuracy compared to the other methods.

A Hands-free Human-Computer-Interface Platform for Paralyzed Patients Using a TENG-based Eyelash Motion Sensor.

People with body disabilities as a result of neurological diseases or physical accidents, face daily troubles in some situations that require arm or finger motions. Access to expensive assistive technologies can be difficult, and job opportunities can be low for patients with limited mobility. Triboelectric nanogenerators (TENGs) bring a new concept enabling the design of special sensors that can be used in Human-Computer-Interfaces (HCIs) to support people with disabilities. In this manuscript, it is proposed a novel eye motion sensor based on TENG integrated into an HCI leading to hands-free typing on the computer. We demonstrate that by controlling the cursor, the user can pick up the characters from a virtual keyboard and write an algorithm in the Integrated-Development-Environment (IDE) of Python language. The novel eye sensor recognizes the eyelash motion detected from the triboelectric interaction between human hair and silicone. It is shown that a user is able to write a simple python program to display a message on the computer without the use of hands. Finally, we hope this development can support disabled patients to improve their programming skills and provide improved job opportunities in areas such as information technology or computer science.

An Automatic Navigation and Pressure Monitoring for Guided Insertion Procedure.

Navigation is an important feature needed for medical insertion procedures. It is required to guide the medical device in the right direction at the right time. Navigation techniques used in the Wireless Capsule Endoscopy and conventional endoscopy fields are based on image-guided systems that require a large amount of data to be transferred and processed computationally. These issues increase system complexity as well as the overall system and procedure costs. Moreover, these systems cannot provide the required information in dark or liquid areas. To improve the medical internal inspections capabilities, we present a pressure direction measurement system that can be implemented for a capsule endoscope; ordinary endoscopy; and any other insertion procedure where navigation and safety are required. The system can operate in dark and liquid areas because no visualization is required. The system consists of a pressure sensor placed on a semi-hemisphere on top of the steering device to detect azimuth and polar angle variation according to the direction at any differentiable path.

A Locomotion Control Platform With Dynamic Electromagnetic Field for Active Capsule Endoscopy.

Conventional radiological and endoscopic techniques utilizing long tubes were ineffective in visualizing the small bowel mucosa until the development of wireless capsule endoscopy (WCE). WCE is a revolutionary endoscopic technology that can diagnose the complete gastrointestinal tract. However, the existing capsule technologies are passive, and thus they cannot be navigated to or held in a specific location. The design of an active capsule will present the opportunity to move and stop a device at any targeted locations leading to numerous medical applications such as drug delivery or collecting tissue samples for examinations in the laboratory. This paper implements a new locomotion methodology for WCE systems using an electromagnetic platform. The platform produces a dynamic electromagnetic field to control the motion of the capsule. The strength and the direction of the electromagnetic field that is generated by the platform are continuously adjusted in order to maintain the equilibrium state during the capsule movement. We present the detailed design of the proposed platform with an experimental setup with polyvinyl chloride tubes and ex vivo to demonstrate the performance of the capsule motion.

A sub 125 nW sub-threshold analog adaptive sampler in 180 nm CMOS.

We present an ultra low power analogue adaptive sampler for extraction of features from an arterial blood pressure signal, prior to ADC operation or conversion. The architecture is implemented and simulated in UMC 180 nm technology. A worst case power consumption across process variation of 124.6 nW was achieved, with a process invariant key-point timing error of approximately 2.31 ms, corresponding to a sample error of magnitude less than 0.1 mmHg, simulated at body temperature of 37°C. This is significantly below the standard clinical recording accuracy of 1 mmHg for electronic measurement tools.

A wireless capsule endoscopy steering mechanism using magnetic field platform.

In this paper, a new steering mechanism for wireless capsule devices is presented. The proposed system consists of a platform generating a magnetic field to direct and control the motion of a capsule. The platform contains an upper and a lower set of electromagnets. A permanent magnet is implanted inside the capsule to initiate the movement, which is set by the magnetic field delivered by the electromagnets. The total magnetic field at the capsule's location is the sum of the contributions of each electromagnet. An experimental setup has been designed for testing and comparing between the performance of the capsule mobility in practice and simulations.

A 180 nm CMOS analog adaptive sampler for blood pressure feature extraction.

This paper presents an analogue feature detector for extraction and sampling of key-points on an arterial blood pressure signal in both humans and small mammals used as human physiological models. A CMOS integrated circuit was implemented in UMC 180nm technology, utilizing the proposed sampling method to greatly reduce the number of samples necessary for meaningful reconstruction of the low bandwidth signal. This circuit was interfaced with an external ADC to fully extract the feature points, and evaluate the system performance. Over the target heart rate range of 1 to 25 Hz, the system outperformed typical home measurement tools for systole and diastole extraction.

Improving resolution of robotic capsule locomotion using dynamic electromagnetic field.

This paper describes a new method to control the motion of swallowable wireless capsule endoscopy devices. A dynamic magnetic field produced by a set of external magnetic coils is used to manage the locomotion of the capsule. A permanent magnet is embedded into the capsule in order to manipulate the capsule by changing the external magnetic field strength for each specific position. The dynamic magnetic field is externally controlled to reach and maintain the equilibrium state for holding the capsule in a specific location. This is achieved by keeping the net force of magnetic fields zero. To start the mobility, the magnetic field from one of the external field sources will be reduced for a certain amount of time by sending an OFF-pulse (a current source). The required forces and the pulses are controlled by a specific algorithm to control the step size of the movement in order to achieve precise motion at any chosen velocity. The proposed method is designed to provide a precise motion control with a system extremely low in complexity.

A 1.04µW wireless integrated MEMS interface in UMC 0.18µm CMOS.

This paper presents an ultra low-power integrated interface for capacitive and resistive MEMS and sensors, intended for use in biomedical applications. The interface encodes the sensed data in the time between transmitted UWB pulses: this reduces the number of transmitted bits and benefits the power consumption. The interface was designed and fabricated in the UMC 0.18µm CMOS process: the power consumption of the system was measured to be 1.04µW at a sample rate of 37Hz.

Wireless power transmission for biomedical implants: The role of near-zero threshold CMOS rectifiers.

Biomedical implants require an electronic power conditioning circuitry to provide a stable electrical power supply. The efficiency of wireless power transmission is strongly dependent on the power conditioning circuitry specifically the rectifier. A cross-connected CMOS bridge rectifier is implemented to demonstrate the impact of thresholds of rectifiers on wireless power transfer. The performance of the proposed rectifier is experimentally compared with a conventional Schottky diode full wave rectifier over 9 cm distance of air and tissue medium between the transmitter and receiver. The output voltage generated by the CMOS rectifier across a 1 KΩ resistive load is around twice as much as the Schottky rectifier.

Electromagnetic and thermal effects of IR-UWB wireless implant systems on the human head.

The usage of implanted wireless transmitting devices inside the human body has become widely popular in recent years. Applications such as multi-channel neural recording systems require high data rates in the wireless transmission link. Because of the inherent advantages provided by Impulse-Radio Ultra Wide Band (IR-UWB) such as high data rate capability, low power consumption and small form factor, there has been an increased research interest in using IR-UWB for bio-medical implant applications. Hence it has become imperative to analyze the electromagnetic effects caused by the use of IR-UWB when it is operated in or near the human body. This paper reports the electromagnetic effects of head implantable transmitting devices operating based on Impulse Radio Ultra Wide Band (IR-UWB) wireless technology. Simulations illustrate the performance of an implantable UWB antenna tuned to operate at 4 GHz with an -10 dB bandwidth of approximately 1 GHz when it is implanted in a human head model. Specific Absorption Rate (SAR), Specific Absorption (SA) and temperature increase are analyzed to compare the compliance of the transmitting device with international safety regulations.

Wireless Body Area Network (WBAN) design techniques and performance evaluation.

In recent years interest in the application of Wireless Body Area Network (WBAN) for patient monitoring applications has grown significantly. A WBAN can be used to develop patient monitoring systems which offer flexibility to medical staff and mobility to patients. Patients monitoring could involve a range of activities including data collection from various body sensors for storage and diagnosis, transmitting data to remote medical databases, and controlling medical appliances, etc. Also, WBANs could operate in an interconnected mode to enable remote patient monitoring using telehealth/e-health applications. A WBAN can also be used to monitor athletes' performance and assist them in training activities. For such applications it is very important that a WBAN collects and transmits data reliably, and in a timely manner to a monitoring entity. In order to address these issues, this paper presents WBAN design techniques for medical applications. We examine the WBAN design issues with particular emphasis on the design of MAC protocols and power consumption profiles of WBAN. Some simulation results are presented to further illustrate the performances of various WBAN design techniques.

Analysis of a multi-access scheme and asynchronous transmit-only UWB for wireless body area networks.

Ultra Wideband (UWB) has many favorable factors for use in a wireless body area network application. The major drawback is the high power consumption of an UWB receiver. One solution to address this problem is to use a transmit-only UWB sensor node. In this paper, we propose a multi-access scheme that is suitable for asynchronous transmit-only UWB wireless body area networks (UWB-WBAN). Each sensor attached on the patient under monitoring is assigned a unique number of UWB pulses per data bit. The number of UWB pulses assigned to the sensors is optimized to improve the bit error rate and system reliability. Simulation shows that through careful selection of the number of pulses for the sensors, it is possible to maintain almost similar bit error probability, regardless of the distance from the receiver.

A 128-channel 6 mW wireless neural recording IC with spike feature extraction and UWB transmitter.

This paper reports a 128-channel neural recording integrated circuit (IC) with on-the-fly spike feature extraction and wireless telemetry. The chip consists of eight 16-channel front-end recording blocks, spike detection and feature extraction digital signal processor (DSP), ultra wideband (UWB) transmitter, and on-chip bias generators. Each recording channel has amplifiers with programmable gain and bandwidth to accommodate different types of biological signals. An analog-to-digital converter (ADC) shared by 16 amplifiers through time-multiplexing results in a balanced trade-off between the power consumption and chip area. A nonlinear energy operator (NEO) based spike detector is implemented for identifying spikes, which are further processed by a digital frequency-shaping filter. The computationally efficient spike detection and feature extraction algorithms attribute to an auspicious DSP implementation on-chip. UWB telemetry is designed to wirelessly transfer raw data from 128 recording channels at a data rate of 90 Mbit/s. The chip is realized in 0.35 mum complementary metal-oxide-semiconductor (CMOS) process with an area of 8.8 x 7.2 mm(2) and consumes 6 mW by employing a sequential turn-on architecture that selectively powers off idle analog circuit blocks. The chip has been tested for electrical specifications and verified in an ex vivo biological environment.

Monitoring of physiological parameters from multiple patients using wireless sensor network.

This paper presents a wireless sensor network system that has the capability to monitor physiological parameters from multiple patient bodies. The system uses the Medical Implant Communication Service band between the sensor nodes and a remote central control unit (CCU) that behaves as a base station. The CCU communicates with another network standard (the internet or a mobile network) for a long distance data transfer. The proposed system offers mobility to patients and flexibility to medical staff to obtain patient's physiological data on demand basis via Internet. A prototype sensor network including hardware, firmware and software designs has been implemented and tested. The developed system has been optimized for power consumption by having the nodes sleep when there is no communication via a bidirectional communication.

Performance evaluation of a Wireless Body Area sensor network for remote patient monitoring.

In recent years, interests in the application of Wireless Body Area Network (WBAN) have grown considerably. A WBAN can be used to develop a patient monitoring system which offers flexibility and mobility to patients. Use of a WBAN will also allow the flexibility of setting up a remote monitoring system via either the internet or an intranet. For such medical systems it is very important that a WBAN can collect and transmit data reliably, and in a timely manner to the monitoring entity. In this paper we examine the performance of an IEEE802.15.4/Zigbee MAC based WBAN operating in different patient monitoring environment. We study the performance of a remote patient monitoring system using an OPNET based simulation model.