Mikael Ekström

Critical review of non-invasive respiratory monitoring in medical care

Respiratory failure can be difficult to predict. It can develop into a life-threatening condition in just a few minutes, or it can build up more slowly. Thus continuous monitoring of respiratory activity should be mandatory in clinical, high-risk situations, and appropriate monitoring equipment could be life-saving. The review considers non-invasive methods and devices claimed to provide information about respiratory rate or depth, or gas exchange. Methods are categorised into those responding to movement, volume and tissue composition detection; air flow; and blood gas concentration. The merits and limitations of the methods and devices are analysed, considering information content and their ability to minimise the rate of false alarms and false non-alarms. It is concluded that the field of non-invasive respiratory monitoring is still in an exploratory phase, with numerous reports on specific device solutions but less work on evaluation and adaptation to clinical requirements. Convincing evidence of the clinical usefulness of respiratory monitors is still lacking. Devices responding only to respiratory rate, and lacking information about actual gas exchange, will have limited clinical value. Furthermore, enhancement in specificity and sensitivity to avoid false alarms and non-alarms will be necessary to meet clinical requirements. Miniature CO2 sensors are identified as one route towards substantial improvement.

Remote system for patient monitoring using Bluetooth/spl trade/

The aim of this study is to design and develop a low-power wireless A/D-converter that should be easy to integrate with other technologies or infrastructures at a low cost. This transmitting unit should be able to replace many of the signal wires between biomedical sensors connecting the patient and the sampling unit or supervision equipment. The model of today is an embedded hardware solution with two processors (FPGA and Bluetooth). A twelve bit ADC with a 1 kHz-sampling rate then converts an analogue signal that simulates an ECG-signal with typical frequencies. The communication between the ADC and Bluetooth/spl trade/ is serial and controlled by the FPGA. The remote PC runs a simple software that controls the Bluetooth/spl trade/ and processes the received data. The results indicate that it is possible to continuously transmit an ECG-signal without losing data.

GIMME - A General Image Multiview Manipulation Engine

This paper presents GIMME (General Image Multiview Manipulation Engine), a highly flexible reconfigurable stand-alone mobile two-camera vision platform with stereo-vision capability. GIMME relies on reconfigurable hard-ware (FPGA) to perform application-specific low to medium-level image-processing at video-rate. The Qseven-extension enables additional processing power. Thanks to its compact design, low power consumption and standardized interfaces (power and communication), GIMME is an ideal vision platform for autonomous and mobile robot applications.

A Bluetooth Radio Energy Consumption Model for Low-Duty-Cycle Applications

This paper presents a realistic model of the radio energy consumption for Bluetooth-equipped sensor nodes used in a low-duty-cycle network. The model is based on empirical energy consumption measurements of Bluetooth modules. This model will give users the possibility to optimize their radio communication with respect to energy consumption while sustaining the data rate. This paper shows that transmission power cannot always be directly related to energy consumption. Measurements indicate that, when the transmission power ranges from -5 to +10 dBm, the difference in consumed energy can be detected for each transmission peak in the sniff peak. However, the change is negligible for the overall energy consumption. The nonlinear behavior of the idle state for both master and slave when increasing the interval and number of attempts is presented. The energy consumption for a master node is in direct relation to the number of slaves and will increase by approximately 50% of the consumption of one slave per additional slave, regardless of the radio setting.

An embedded stereo vision module for 6D pose estimation and mapping

This paper presents an embedded vision system based on reconfigurable hardware (FPGA) and two CMOS cameras to perform stereo image processing and 3D mapping for autonomous navigation. We propose an EKF based visual SLAM and sparse feature detectors to achieve 6D localization of the vehicle in non flat scenarios. The system can operate regardless of the odometry information from the vehicle since visual odometry is used. As a result, the final system is compact and easy to install and configure.

New CO/sub 2/ sensor with high resolution and fast response

The most common principles for CO/sub 2/ sensors are only partially fulfilling the requirements of cardiovascular and respiratory applications. A new acoustic sensor principle is claimed to be favorable in several respects, such as size, resolution, response time, reliability and cost. The sensor makes use of an electro acoustic element coupled to a Kundt resonator. The resonance frequency is determined by the mean molecular mass of the gas contained in the resonator, which may, in turn, be dominated by the variations of CO/sub 2/ concentration. A phased locked loop (PLL) oscillator provides both voltage and frequency outputs of the sensor. In this paper, a prototype design is presented, along with experimental results demonstrating that resolution, linearity and response time adequate for biomedical applications may be achieved.

Steps towards a minimal mobile wireless Bluetooth/sup TM/ sensor

This paper describes a new Bluetooth/sup TM/-based wireless implementation of a mobile sensor. The solution reduces dramatically both power consumption and size of a wireless sensor improving earlier Bluetooth/sup TM/ implementations where multi-chip solutions were used and mobility was not supported. Three different implementations from multi-chip to single chip are described with the sensor wireless interface, the architecture, protocols and algorithms used. Achieved results are: (1) Implementation of 1 chip solution wireless sensor using the internal Bluetooth/sup TM/ module ADC for external sensing purposes. (2) Mobile sensor wireless monitoring with Bluetooth/sup TM/.

Optimization of wireless Bluetooth sensor systems.

Within this study, three different Bluetooth/spl trade/ sensor systems, replacing cables for transmission of biomedical sensor data, have been designed and evaluated. The three sensor architectures are built on 1-, 2- and 3-chip solutions and depending on the monitoring situation and signal character, different solutions are optimal. Essential parameters for all systems have been low physical weight and small size, resistance to interference and interoperability with other technologies as global- or local networks, PCs and mobile phones. Two different biomedical input signals, ECG and PPG (photoplethysmography), have been used to evaluate the three solutions. The study shows that it is possibly to continuously transmit an analogue signal. At low sampling rates and slowly varying parameters, as monitoring the heart rate with PPG, the 1-chip solution is the most suitable, offering low power consumption and thus a longer battery lifetime or a smaller battery, minimizing the weight of the sensor system. On the other hand, when a higher sampling rate is required, as an ECG, the 3-chip architecture, with a FPGA or micro-controller, offers the best solution and performance. Our conclusion is that Bluetooth/spl trade/ might be useful in replacing cables of medical monitoring systems.

An embedded stereo vision module for industrial vehicles automation

This paper presents an embedded vision system based on reconfigurable hardware (FPGA) to perform stereo image processing and 3D mapping of sparse features for autonomous navigation and obstacle detection in industrial settings. We propose an EKF based visual SLAM to achieve a 6D localization of the vehicle even in non flat scenarios. The system uses vision as the only source of information. As a consequence, it operates regardless of the odometry from the vehicle since visual odometry is used.

Bluetooth energy characteristics in wireless sensor networks

In this paper a measurement system to create an experimental model and a tool box for simulations concerning both the energy consumption and the time aspect when creating wireless sensor networks using Bluetooth 2.0 + enhanced data rate has been developed. Further energy and time characteristics for critical events when using Bluetooth 2.0 in wireless sensor networks are investigated experimentally, with the main events; create connection, send data, receive data, and idle state. Results show that when allowing higher latencies for the connection in the Wireless Sensor Networks the power consumption drops drastically when using low power mode as sniff.