Fernando Seoane

Removing respiratory artefacts from transthoracic bioimpedance spectroscopy measurements

Transthoracic impedance spectroscopy (TIS) measurements from wearable textile electrodes provide a tool to remotely and non-invasively monitor patient health. However, breathing and cardiac process ...

Wearable Cardiorespiratory Monitoring System for Unobtrusive Free-Living Energy Expenditure Tracking

In this work, we want to introduce combined heart rate and respiration monitoring for more accurate energy expenditure tracking on free-living subjects. We have developed a wearable cardiorespiratory monitoring system with unobtrusive heart rate measurement and ventilation estimation function for this purpose. The system is based on a garment with integrated textile electrodes for one-lead electrocardiogram and impedance pneumography measurements. A pilot experiment has been performed to prove the concept and to evaluate the characteristics of heart rate and ventilation estimated by our system in relation to energy expenditure. In the experiment, ventilation shows a better linearity in relation to the energy expenditure at the low intensity region than heart rate. Based on these characteristics, a model combining heart rate and ventilation for energy expenditure estimation is proposed which shows a significantly lower estimation error than the heart rate only model.

Tunable flexible artificial synapses: a new path toward a wearable electronic system

The flexible electronics has been deemed to be a promising approach to the wearable electronic systems. However, the mismatching between the existing flexible deices and the conventional computing paradigm results an impasse in this field. In this work, a new way to access to this goal is proposed by combining flexible devices and the neuromorphic architecture together. To achieve that, a high-performance flexible artificial synapse is created based on a carefully designed and optimized memristive transistor. The device exhibits high-performance which has near-linear non-volatile resistance change under 10,000 identical pulse signals within the 515% dynamic range, and has the energy consumption as low as 45u2009fJ per pulse. It also displays multiple synaptic plasticity features, which demonstrates its potential for real-time online learning. Besides, the adaptability by virtue of its three-terminal structure specifically contributes its improved uniformity, repeatability, and reduced power consumption. This work offers a very viable solution for the future wearable computing.Artificial synapses: memristive transistors with mechanical and synaptic flexibilityMechanically flexible artificial synapses based on memristive transistors demonstrate different kinds of synaptic plasticity. The synapse is a fundamental component in neuromorphic computing (a brain-inspired computing approach that aims to provide more efficient computing compared to conventional approaches). Yiqiang Zhan, Lirong Zheng, and Fernando Seoane with collaborators in Sweden and China now report an artificial synapse based on a memristive transistor that is mechanically flexible. Key to the design of their synapse is a three-terminal structure, which enables gate tuning. The ability to adjust the voltage on the gate terminal enables variations in the device to be compensated thereby improving performance uniformity and repeatability. The researchers also show that gate tuning can reduce the total energy consumption per spiking event to 45u2009fJ and demonstrate a variety of synaptic plastic features important for replicating neuromorphic behavior.

Electrical bioimpedance enabling prompt intervention in traumatic brain injury

Electrical Bioimpedance (EBI) is a well spread technology used in clinical practice across the world. Advancements in Textile material technology with conductive textile fabrics and textile-electronics integration have allowed exploring potential applications for Wearable Measurement Sensors and Systems exploiting. The sensing principle of electrical bioimpedance is based on the intrinsic passive dielectric properties of biological tissue. Using a pair of electrodes, tissue is electrically stimulated and the electrical response can be sensed with another pair of surface electrodes. EBI spectroscopy application for cerebral monitoring of neurological conditions such as stroke and perinatal asphyxia in newborns have been justified using animal studies and computational simulations. Such studies have shown proof of principle that neurological pathologies indeed modify the dielectric composition of the brain that is detectable via EBI. Similar to stroke, Traumatic Brain Injury (TBI) also affects the dielectric properties of brain tissue that can be detected via EBI measurements. Considering the portable and noninvasive characteristics of EBI it is potentially useful for prehospital triage of TBI patients where. In the battlefield blast induced Traumatic Brain Injuries are very common. Brain damage must be assessed promptly to have a chance to prevent severe damage or eventually death. The relatively low-complexity of the sensing hardware required for EBI sensing and the already proven compatibility with textile electrodes suggest the EBI technology is indeed a candidate for developing a handheld device equipped with a sensorized textile cap to produce an examination in minutes for enabling medically-guided prompt intervention.