Sensor Developments for Electrophysiological Monitoring in Healthcare

Recent years have seen a renewal of interest in the development of sensor systems which can be used to monitor electrophysiological signals in a number of different settings. These include clinical, outside of the clinical setting with the subject ambulatory and going about their daily lives, and over long periods. The primary impetus for this is the challenge of providing healthcare for the ageing population based on home health monitoring, telehealth and telemedicine. Another stimulus is the demand for life sign monitoring of critical personnel such as fire fighters and military combatants. A related area of interest which, whilst not in the category of healthcare, utilises many of the same approaches, is that of sports physiology for both professional athletes and for recreation. Clinical diagnosis of conditions in, for example, cardiology and neurology remain based on conventional sensors, using established electrodes and well understood electrode placements. However, the demands of long term health monitoring, rehabilitation support and assistive technology for the disabled and elderly are leading research groups such as ours towards novel sensors, wearable and wireless enabled systems and flexible sensor arrays

Functional characterization of developing heart in embryos using Electric Potential Sensors

The characterization of the electrocardiographic activity of the living zebrafish heart during early developmental stages is a challenging task. Most of the available techniques are limited to heartbeat rate quantification being this inaccurate. Other invasive methodologies require the insertion of electrodes noise isolated environments and advanced amplification stages making these techniques very expensive. In this paper, we present a novel and non-invasive sensor development to characterize the functional activity of the developing heart of in vivo zebrafish embryos. The design is based on the Electric Potential Sensing technology patented at Sussex which has been developed to achieve reproducibility and continuous detection. We present preliminary functional characterization data of the developing zebrafish heart starting at 3 days-post-fertilization. Results show that using the proposed system for mapping the electrocardiographic activity of the zebrafish heart at early developmental stages is successfully accomplished. This is the first time that such a sensitive sensor has been developed for measuring the electrical changes occurring on micron sized (< 100 µm) living samples such as the zebrafish heart

Electric field phase sensing for wearable orientation and localisation applications

We show how to sense the phase of the ambient electric field from a body-worn sensor with respect to a reference and discuss how phase information could contribute to relative orientation sensing and indoor localisation. Our system uses 7mW and can be enclosed in a plastic case which makes it suitable for new wearable devices

Maximising Synergy among Tropical Plant Systematists, Ecologists, and Evolutionary Biologists

Closer collaboration among ecologists, systematists, and evolutionary biologists working in tropical forests, centred on studies within long-term permanent plots, would be highly beneficial for their respective fields. With a key unifying theme of the importance of vouchered collection and precise identification of species, especially rare ones, we identify four priority areas where improving links between these communities could achieve significant progress in biodiversity and conservation science: (i) increasing the pace of species discovery; (ii) documenting species turnover across space and time; (iii) improving models of ecosystem change; and (iv) understanding the evolutionary assembly of communities and biomes

Hardware Comb Filter Enhances Dynamic Range and Noise Performance of Sensors in Noisy Environments

We present the results of combining a hardware implementation of an analog comb filter with an ultralow noise electromagnetic sensor. The comb filter is designed to attenuate mains related interference, at either 50 or 60 Hz, and related harmonics. The sensor chosen for this work is an induction magnetometer, but the method is applicable to any low noise high dynamic range sensor. The resultant system, in this case, uses only a single coil, not a gradiometric configuration, thus providing a magnetometer capable of sensing field as opposed to field gradient. This combination of filter and sensor allows additional gain to be added and the full sensitivity of the system to be achieved, previously only realized in an electromagnetically screened room. At the same time, the high dynamic range, low noise performance, and original bandwidth of the sensor are maintained. The technique is illustrated by using the system in an urban environment to observe Schumann resonance phenomena. This approach to acquiring small signals in a noisy environment is compared with conventional analog filter and digital signal processing techniques

Security applications of a remote electric-field sensor technology

A new generation of electric field sensors developed at the University of Sussex is enabling an alternative to contact voltage and non-contact magnetic field measurements. We have demonstrated the capability of this technology in a number of areas including ECG through clothing, remote off-body ECG, through wall movement sensing and electric field imaging. Clearly, there are many applications for a generic sensor technology with this capability, including long term vital sign monitoring. The non-invasive nature of the measurement also makes these sensors ideal for man/machine and human/robot interfacing. In addition, there are obvious security and biometric possibilities since we can obtain physiological data remotely, without the knowledge of the subject. This is a clear advantage if such systems are to be used for evaluating the psychological state of a subject. In this paper we report the results obtained with a new version of the sensor which is capable of acquiring electrophysiological signals remotely in an open unshielded laboratory. We believe that this technology opens up a new area of remote biometrics which could have considerable implications for security applications. We have also demonstrated the ability of EPS to function in closely-packed one and two dimensional arrays for real-time imaging. © 2008 SPI

Application of smart electric potential sensors

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Towards the correlation between human hydration and the electrical activity of the heart using Electric Potential Sensors

Dehydration has been associated with several adverse effects on health and well-being such as the progressive reduction in the ability to concentrate as well as the levels of alertness when fluid intake is restricted. Currently, hydration assessment has been performed using various methods ranging from simple clinical procedures to more complex techniques. However, most of these currently used technologies are not accurate and in some cases are extremely invasive. In this paper we propose a new methodology to assess human hydration using Electric Potential Sensing technology. It is based on measuring the electric field generated by the human body. We propose to correlate the electrical activity of the heart with different levels of human hydration. For evaluating this proof of principle the proposed methodology was assessed considering several healthy subjects. The results presented show that it is possible to assess the level of hydration by measuring changes in the electric field generated by the heart using our proposed sensor technology

A novel non-invasive sensor based on electric field detection for cardio-electrophysiology in zebrafish embryos

Currently, there is no effective sensing technology available to monitor the electrocardiogram activity of the living zebrafish heart during early developmental stages. Most of the methods are based either on the use of simple visual inspections which are limited to quantifying the heart rate or invasive methodologies which require the insertion of electrodes or heart explantation techniques both requiring the use of expensive differential amplifiers and noise isolated environments. In this paper we report the continuous detection of the cardiac electrical activity in embryonic zebrafish using a non-invasive approach. We present a portable and cost-effective platform based on the Electric Potential Sensing technology, to monitor in vivo electrocardiogram activity from the zebrafish heart. This proof of principle demonstration shows how electrocardiogram measurements from embryonic zebrafish may become accessible by using the electric field detection method. We present results obtained using the experimental prototype, which enables the acquisition of cardio-electrophysiological signals from in vivo zebrafish embryos

Non-invasive electrocardiogram detection of in vivo zebrafish embryos using electric potential sensors

In this Letter we report the continuous detection of the cardiac electrical activity in embryonic zebrafish using a non-invasive approach. We present a portable and cost-effective platform based on the Electric Potential Sensing technology, to monitor in vivo electrocardiogram activity from the zebrafish heart. This proof of principle demonstration shows how electrocardiogram measurements from embryonic zebrafish may become accessible by using electric field detection. We present preliminary results using the prototype, which enables the acquisition of electrophysiological signals from in vivo 3 and 5 days-post-fertilization zebrafish embryos. The recorded waveforms show electrocardiogram traces including detailed features such as QRS complex, P and T waves