Spiking Chemical Sensor (SCS): A new platform for neuro-chemical sensing

Published versio

Towards a Reconfigurable Sense-and-Stimulate Neural Interface Generating Biphasic Interleaved Stimulus

Published versio

Pressure stimulated currents in rocks and their correlation with mechanical properties

The spontaneous electrification of marble samples was studied while they were subjected to uniaxial stress. The Pressure Stimulated Current (PSC) technique was applied to measure the charge released from compressed Dionysos marble samples, while they were subjected to cyclic loading. The experimental results demonstrate that, in the linear elastic region of the sample, no PSC is recorded, while beyond the stress limit (s>0.60), observable variations appear, which increase considerably in the vicinity of sample failure, reaching a maximum value just before the failure. The emitted current is reduced on each loading cycle and it has a reciprocal dependence to the normalized Young modulus. The MCD model, applied out of the vicinity of sample failure explains successfully the above findings. The existence of a "memory-like" behavior of the sample, could justify the weakness or absence of electrical earthquake precursors, during an aftershock sequence

Piezo stimulated currents in marble samples: precursory and concurrent-with-failure signals

International audienceThe Earth?s electric field transient variations are promising candidates of earthquake precursors. In order to study the physical mechanisms of such precursory signals, laboratory experiments of uniaxial compression were carried out. More specifically the behaviour of stressed marble samples from Penteli Mountain was investigated. The samples were subjected to a time-varying uniaxial compression at both variable and constant stress rates. During the first set of experiments weak electric currents were detected during pressure variations. Such Piezo Stimulated Currents (PSC) were detected while stress steps, both positive and negative were applied, the maximum stress never being greater than the elasticity limit. During the second set of experiments stress was applied at a constant rate starting from zero-stress and ending in fracture. In the region beyond the elastic limit a PSC was detected which after reaching a peak suffered a reversal in its polarity just before fracture. In a third set of experiments the same procedure was applied to previously structurally damaged samples taking care not to fracture them. In all cases the PSC followed the variation of stress and moreover it was observed that a linear relationship existed between the PSC maxima and the corresponding stress-rate maxima. The mechanism responsible for the described phenomena can be ascribed to the Moving Charged Dislocations model

Pressure Stimulated Currents (PSC)in marble samples

The electrical behaviour of marble samples from Penteli Mountain was studied while they were subjected to uniaxial stress. The application of consecutive impulsive variations of uniaxial stress to thirty connatural samples produced Pressure Stimulated Currents (PSC). The linear relationship between the recorded PSC and the applied variation rate was investigated. The main results are the following: as far as the samples were under pressure corresponding to their elastic region, the maximum PSC value obeyed a linear law with respect to pressure variation. In the plastic region deviations were observed which were due to variations of Young s modulus. Furthermore, a special burst form of PSC recordings during failure is presented. The latter is emitted when irregular longitudinal splitting is observed during failure

Correlation of pressure stimulated currents in rocks with the damage parameter

Pressure Stimulated Current (PSC) experiments were conducted on marble samples to correlate PSC with the damage parameter, D. The phenomena and procedures taking place in the vicinity of the fracture limit were observed and analytically described. PSC recordings were conducted by application of uniaxial compressional stress, both at a constant stress rate and at a constant deformation rate. A linear relationship was shown to exist between the emitted PSC and the damage parameter which quantifies the deviation from linear elasticity and the concentration of microcracks

A Programmable Neural Interface for Investigating Arbitrary Stimulation Strategies

Accepted versio

Review of Advances in the Measurement of Skin Hydration Based on Sensing of Optical and Electrical Tissue Properties

The presence of water in the skin is crucial for maintaining the properties and functions of the skin, in particular its outermost layer, known as the stratum corneum, which consists of a lipid barrier. External exposures can affect the skin’s hydration levels and in turn, alter its mechanical and physical properties. Monitoring these alterations in the skin’s water content can be applicable in clinical, cosmetic, athletic and personal settings. Many techniques measuring this parameter have been investigated, with electrical-based methods currently being widely used in commercial devices. Furthermore, the exploration of optical techniques to measure hydration is growing due to the outcomes observed through the penetration of light at differing levels. This paper comprehensively reviews such measurement techniques, focusing on recent experimental studies and state-of-the-art devices

Making Sense of Electrical Stimulation: A Meta-analysis for Wound Healing

Electrical stimulation as a mode of external enhancement factor in wound healing has been explored widely. It has proven to have multidimensional effects in wound healing including antibacterial, galvanotaxis, growth factor secretion, proliferation, transdifferentiation, angiogenesis, etc. Despite such vast exploration, this modality has not yet been established as an accepted method for treatment. This article reviews and analyzes the approaches of using electrical stimulation to modulate wound healing and discusses the incoherence in approaches towards reporting the effect of stimulation on the healing process. The analysis starts by discussing various processes adapted in in vitro, in vivo, and clinical practices. Later it is focused on in vitro approaches directed to various stages of wound healing. Based on the analysis, a protocol is put forward for reporting in vitro works in such a way that the outcomes of the experiment are replicable and scalable in other setups. This work proposes a ground of unification for all the in vitro approaches in a more sensible manner, which can be further explored for translating in vitro approaches to complex tissue stimulation to establish electrical stimulation as a controlled clinical method for modulating wound healing