David Naranjo

A First Approach to the Harmonization of Intrabody Communications Measurements

Intrabody Communications (IBC) is a technique that uses the human body as a transmission medium for electri- cal signals, thereby providing an efficient communication cha- nnel for Body Sensor Networks (BSN). Nevertheless, a metho- dology for IBC experimentation that reduces the disparity bet- ween authors’ outcomes and helps to develop standardized IBC prototypes is still required. With the purpose of obtaining a first approach to the harmonization of IBC measurements, two set- ups for both galvanic and capacitive coupling have been imple- mented in this work. A comparative study addressing key para- meters such as frequency range, type of electrodes and ground- ing strategies has been carried out to obtain some practical rules to tackle IBC performance.

Applications of Bioimpedance to End Stage Renal Disease (ESRD)

This chapter develops a thorough review of the methods and techniques used for the analysis of body composition of renal patients based on bioimpedance measurements. The work ranges from the physical principles, to bioelectric models of human body, instrumentation, configurations in the position of electrodes, equations to calculate body composition, bioimpedance nephrological applications and clinical analysis of results. This text provides a multidisciplinary approach that will allow the reader to understand and comprehend this kind of technology, so it can be used both by engineers as a basis for the development of bioimpedance medical devices, and by medical staff to apply the bioimpedance analysis techniques in a better control and management of patients with ESRD.

Multi-Device Information Management for Real-Time Processing of Biomedical Signals

This paper proposes a first approach to multidevice information management developed by a Personal Intelligent Platform (PIP) for pervasive care. This platform must satisfy the specific requirements imposed by the distributed and real-time processing of acquired data from biomedical smart sensors carried by the monitored user. The multi-device management system analyzed meets these restrictions, optimizing the processing of heterogeneous signals from different sensors. For this purposes, results are analyzed in terms of time performance for the case of use of fall detection by means of accelerometer smart sensors.

A Distributed-Parameter Approach to Model Galvanic and Capacitive Coupling for Intra-body Communications

In this paper, we propose a simple, but accurate propagation model through the skin based on a RGC distributed-parameter circuit that leads to the obtaining of simple and general attenuation expressions for both galvanic and capacitive coupling methods that could assist in the design of Intra-body Communications (IBC) systems. The objective of this model is to study the influence of the skin impedance in the propagation characteristics of a particular signal. In order to depict that skin impedance, the model is based on the major electro-physiological properties of the skin, which also allows a personalized model. Simulation results have been successfully compared with several published results, thus showing the tuning capability of the model to different experimental conditions.

Design and Validation of an Electric Circuit Phantom for Galvanic Intrabody Communication

Intrabody Communication (IBC) still poses important technical issues regarding the measurement of pathloss through the human body. In the literature, a number of experimental setups using different measurement equipment and conditions have been proposed, possibly causing the discrepancy observed among results by diverse authors. In addition, the uncertainty caused by the human body represents a challenge in the measurement process, thus making it hard to distinguish the human effects from those related to the measurement conditions and equipment used. For this reason, an electric circuit phantom has been proposed in this work, with the aim of obtaining a prototype with which IBC designers can validate their experimental setups, thereby allowing the effects due to measurement equipment to be identified. This phantom is based on a simplified four-impedance circuit model which approximately emulates bioimpedance and pathloss for IBC galvanic coupling. Finally, the applicability of the phantom has been validated by conducting a set of measurements on the human arm.

Experimental Characterization of Active Antennas for Body Sensor Networks

This paper addresses methods for experimental characterization of active antennas in the context of Body Sensor Networks (BSN). In a previous work, the authors proposed an active antenna design to be used in a biomedical monitoring network, following specifications such as consumption, size and cost minimization. In this work, such an antenna has been integrated with the transceiver in the same device and characterized experimentally using active measurement methods. First, two sets of measurements were performed both with and without the presence of a human body in order to analyze its influence on the antenna performance. Subsequently, the active antenna was characterized inside an anechoic chamber in order to obtain more comprehensive parameters, thus presenting a method for obtaining the radiation patterns of antennas integrated into battery-powered smart sensors.

Analysis of Anomalies in Bioimpedance Models for the Estimation of Body Composition

Bioimpedance analysis is a simple, safe and noninvasive method for Body Composition Estimation (BCE), which is of great interest for the monitoring of patients on renal replacement therapy. The most featured bioimpedance devices available are based on the bioimpedance spectroscopy technique, the extended Cole model and the Hanai Mixture theory. However, a set of anomalies using these methods has been found in this paper during the study of the evolution of body composition in patients on peritoneal dialysis. The main results obtained show that the estimates resulting from bioimpedance values that differ significantly from the single-dispersion Cole model have to be taken with some caution. This issue highlights the importance of medical assessment (technical or specialist) when interpreting any bioimpedance related data.

Remote Programming of Biomedical Smart Sensors

This paper proposes a processing architecture and a programming framework for the remote and seamless update of the algorithms used in the context of biomedical smart sensors. The generic processing architecture provides, among others, the following facilities to a Body Sensor Network in a seamless way to the user beyond functional modularity: 1) direct and immediate update with new and improved versions of the algorithms, 2) personalization of algorithms, 3) adaptability to the user context, 4) remote test of algorithms, 5) hardware reusability and sustainability, 6) parallel execution of several monitoring applications in one device, 7) structural modularity. Due to its simplicity, the proposed technique takes advantage over other solutions employed in applications that impose severe limitations on hardware/software resources of the devices, which may result in lower cost and size of them. The results obtained on two heart monitoring applications shows the viability of the proposed scheme.

A Personalized Model for Galvanic Coupling in Intrabody Communication Systems

Intrabody communication (IBC) uses the human body as a transmission medium for electrical signals, providing an efficient channel to interconnect devices in Body Sensor Networks. For IBC galvanic coupling, the signal path is accomplished through two pairs of electrodes deployed on the skin, which suggest the dependence of the attenuation signal on the subject’s electrophysiological skin properties. With the purpose of gaining an insight into the attenuation differences observed for diverse subjects, a simple transmission line-based model has been used for the identification of those personalized parameters that best emulate the attenuation behavior. Experimental results for two different subjects have been carried out using a harmonized measurement set-up. Model simulations have shown to match measurement data more accurately when individualized instead standard skin parameters were used, thus highlighting the need to deal with personalized models in IBC research.

Optimization procedure for the impact detection thresholds in an Accelerometer Smart Sensor

The main objective of this work is to perform an optimization methodology of the temporal parameters and operation thresholds (acceleration and energy) for the impact detection in an Accelerometer Smart Sensor. The procedure is based on a sequential approach to values that improve the sensitivity and the specificity of the impact detection. It was fed in its execution with a set of experiments of different daily activities, with and without impact. The values of the parameters obtained from the optimization were tested with a different set of experiments achieving a 100% success (zero false positives and zero false negatives), confirming the robustness of the procedure.