2,634 research outputs found
A Wearable Device for High-Frequency EEG Signal Recording
No full textThe recording of high-frequency oscillations (HFO) through the skull has been investigated in the last years highlighting interesting new correlations between the EEG signals and common mental diseases. Therefore, since most of the commercially available EEG acquisition systems are focused on the low frequency signals, a wide-band EEG recorder is here presented. The proposed system is designed for those applications in which a wearable and user-friendly device is required. Using a standard Bluetooth (BT) module to transfers the acquired signals to a remote back-end, it can be easily interfaced with the nowadays widely spread smartphones or tablets by means of a mobile-based application. A Component Off-The-Shelf (COTS) device was designed on a 19 cm2 custom PCB with a low-power 8-channel acquisition module and a 24−bit Analog to Digital Converter (ADC). The presented system, validated through in-vivo experiments, allows EEG signals recording at different sample rates, with a maximum bandwidth of 524 Hz, and exhibits a maximum power consumption of 270 mW
The Classics of the First Lorenzo de' Medici. For a New Critical Reading of Corinth
No full textopenIl presente lavoro si propone di rileggere una delle prime opere di Lorenzo de’ Medici, "Corinto", attraverso temi letterari che lo caratterizzano, tenendo presente i modelli latini, greci e italiani ai quali l’autore attinge e confrontandone altri, pertinenti ai temi analizzati. Dopo una rapida introduzione sul contesto storico in cui il poemetto si inserisce, esso viene presentato per quanto concerne il contenuto e la storia redazionale, approfondita nell’Appendice, dove si presentano inoltre i testi di riferimento. Segue dunque la nuova lettura critica. La riflessione sul concetto di classico e su Lorenzo quale autore e personaggio del poemetto conclude l’analisi.The present work aims to re-read one of Lorenzo de’ Medici’s first works, "Corinto", through the literary themes which characterize it, keeping in mind the Latin, Greek and Italian models on which the author draws and comparing others, pertinent to the themes analyzed. After a quick introduction to the historical context in which the poem fits, it is presented in terms of content and editorial history, detailed in the Appendix, where the reference texts are also presented. Thus follows the new critical reading. The reflection on the concept of classic and on Lorenzo as author and character of the poem concludes the analysis
A low power wireless and wearable 8-channels EEG recording system
No full textThe electroencephalography (EEG) is a technique commonly used for detecting symptoms of
neurological diseases such as epilepsy, sleep disorders, anxiety and learning disabilities that are
quite diffused and with a great impact on people common life. Most of the mentioned mental
disorders require long term EEG monitoring, possibly during daily life activities, to follow the
course of the disease and sometimes to prevent further degradations of the patient condition.
Generally, the longer the EEG measurement period isthe higher is the probability of a successful
event detection. Allowing only few hours of observation time with high costs and resource
overheads, traditional inpatient ambulatory EEG systems don’t satisfy these requirements. It is only
recently that technology innovations have led to new outpatient EEG systems. They are mobile
solutions that overcome some of these limitations reducing the overall patient monitoring costs and
increasing the effectiveness of the measurements [1]. Despite their benefits, such systems are still
cumbersome with some problems related to the electrode-skin adherence, to the data storage
capability and to the battery life time. Wearable EEG such as those presented in [2] and [3], are
aimed to overcome these issues, allowing the recording of a longer temporal window that includes
all stages of sleep and wakefulness and increasing the likelihood of recording typical symptoms.
The wearable EEG system proposed in this paper is based on a custom PCB with off-the-shelf
components. Being a wearable device, special efforts were made in reducing its power consumption
and in device miniaturization. As a result, only the essential components were included in the
project: an amplyfing/filtering block, an analog todigital converter, a micro-controller, a bluetooth
transceiver and a power management module. The designed system, depicted in Fig. 1, contains a
differential 8 channel recording unit. The EEG signals detected with a standard EEG cap are first
amplified and then converted into a 24-bit digital signals by an ADS1299 from Texas Instrument.
Once acquired, digital signals are transmitted to a remote backend by means of a Microchip
Bluetooth RN-42 module. Moreover, a USB connection was introduced to charge the EEG recorder
battery and as additional channel for data transfer. A custom firmware was written for a Microchip
PIC18F46J50 to coordinate data exchange between ADCand Bluetooth or USB external controller.
The main constraint was the real time data exchange at sampling frequency up to 2000SPS. In
addition a power management unit generates all digital and analog voltage supplies from a 3.7V-950mAh LiPo battery. Even the battery charging circuit was implemented on the board. The EEG
recorder was realized on the 5.5cm X 3.5cm double face board depicted in Fig.2. Possible remote
controllers for wearable EEG recording applicationsare the nowadays widely diffused smartphone
or tablet. So that an open source and user-friendly software application based, for example, on
Android operative system, can be a target solution to interface our EEG recorder. At this first stage
of the system development a Visual C++ application was written for the EEG recorder testing
purpose. The small dimensions of the realized system and its maximum 270mW of power
consumption make it suitable for up to 13 hours of continuous EEG recording without encumbering
any daily life activity. As depicted in Fig. 3 and Fig. 4, some in-vivo measurements were performed
comparing our device with a standard laboratory equipment
A wearable device for high-frequency EEG signal recording
No full textThe recording of high-frequency oscillations (HFO) through the skull has been investigated in the last years highlighting interesting new correlations between the EEG signals and common mental diseases. Therefore, since most of the commercially available EEG acquisition systems are focused on the low frequency signals, a wide-band EEG recorder is here presented. The proposed system is designed for those applications in which a wearable and user-friendly device is required. Using a standard Bluetooth (BT) module to transfers the acquired signals to a remote back-end, it can be easily interfaced with the nowadays widely spread smartphones or tablets by means of a mobile-based application. A Component Off-The-Shelf (COTS) device was designed on a 19 cm2 custom PCB with a low-power 8-channel acquisition module and a 24−bit Analog to Digital Converter (ADC). The presented system, validated through in-vivo experiments, allows EEG signals recording at different sample rates, with a maximum bandwidth of 524 Hz, and exhibits a maximum power consumption of 270 mW
Implantable recording/stimulating neural interface for peripheral nervous system
No full textIn recent years many researchers have focused their attention on the development and on the
clinical experimentation of neural prosthesis [1] for hand amputees. Recent achievements in this
field have made this challenge easier with the introduction of innovative biocompatible materials
and the production of smart, light, artificial limbs characterized by lots of freedom degrees [2].
Despite such improvements, the communication between an implanted electrode and a prosthetic
limb is still an open issue, due to long cables and cumbersome electronic equipments that typically
separate them. In this contest it is very important the miniaturization of the electronic used to
acquire the neural signals from efferent fibers of the Peripheral Nervous System (PNS) and to
elicitate the afferent axons in order to restore the sensory feedback. Due to the weak amplitude of
neural signals, this kind of design is particularly critical. Indeed neural signals are drowned in a
noisy environment characterized by other biological electrical sources such as Electromyographic
(EMG) interferences which have amplitudes many orders of magnitude greater than that of the
neural signal and a bandwidth very close to them. Our group proposes an approach based on sigma
delta converters that reduces the complexity in the analog (implanted) part and shifts the critical
points on the digital side.
A novel bidirectional interface for implantable PNS electrodes has been conceived, designed and is
currently in the manufacturing phase after tape-out. In Fig.1 is depicted the system which is
composed of two main blocks: the analog implantable CMOS circuit and the digital system
controller, implemented on a FPGA. The recording unit (CMOS chip) contains a band-pass filter, a
sigma-delta modulator and a current-output stimulator. The decimation module of the sigma/delta
converter is located on an external digital device (implemented on a FPGA) which implements also
a highly selective filter to separate the neural signal (800 Hz – 8kHz) from electromyographic
interferences (100 Hz – 500 Hz). Such architecture was chosen to put in the implantable chip only
the most critical analog modules while, at the same time, having a robust digital communication
interface with the outside world. In this way, the digital communication protocol is more simple to
implement and more robust to interferences and the implantable chip does not contain power
hungry, sophisticated digital modules.
The implantable device was designed on an austriamicrosystems 0.35um process. The chip layout is
shown in Fig. 2. The chip contains 8 parallel readout channels and has a 4.1mm x 4.1mm die size.
Several parameters (amplifier gain, opamp bandwidths, etc.) are programmable. Power
consumption ranges from 20mW to 27.2mW depending on the operating mode. Each channel has
an overall precision (taking into consideration noise and errors of all the blocks in the acquisition
chain) of 10.4 bit. Fig. 3 shows the post-layout simulation results (including transient noise) for an
input trace obtained from real measurements of an electrode implanted in a rat sciatic nerve. The
original signal is largely affected by low-frequency noise (ECG and EMG) which is completely
removed by the system. The simulation includes the off-chip decimation module
A novel embedded system for direct, programmable stimulation of the peripheral neural system
No full textA device aimed at restoring the sensory feedback in amputees is presented. Biphasic current pulses can be generated and delivered to the Peripheral Neural System (PNS) through neural electrodes. The current pulses can be controlled in terms of amplitude, width and frequency. Moreover, the system can be configured to generate customized waveforms. The device is based on an IC implemented on a 0.35um HV process and includes a voltage booster and a programmable current DAC, allowing to deliver the programmed current even in case of high impedance contact at the electrode-tissue interface. The system has been implemented and successfully tested by means of in-vivo experiments with rats
An HV-CMOS integrated circuit for neural stimulation in prosthetic applications
No full textAn integrated neural stimulator for prosthetic applications,
realized with a high-voltage CMOS 0.35-μm process, is
presented. The device is able to provide biphasic current pulses
to stimulate eight electrodes independently. A voltage booster
generates a 17-V voltage supply in order to guarantee the programmed
stimulation current even in case of high impedances
at the electrode–tissue interface. Pulse parameters such as amplitude,
frequency, and width can be programmed digitally. The
device has been successfully tested by means of both electrical and
in vivo tests, and the results show its capability to provide currents
on the order of hundreds of microamperes with impedances on the
order of tens of kiloohms
An embedded system based on a IC for neural impedance measurement
No full textIn this paper a system aimed at measuring the impedance in a neural interface is presented. The device core is an Integrated Circuit (IC) realized in a CMOS 0.35 m technology. It includes eight different channels allowing to independently measure the impedance of multi-channel electrodes. The IC is composed of two main parts: a current generator based on a DAC and a sigma delta converter for neural recording. The device has been designed, realized and successfully tested by means of electrical tests. It occupies an area of 3.7mmx4.1mm and consumes an overall power of 16mW, the device can measure the impedance both in DC and in AC mode and can be configured in two different operating modes, covering an overall impedance range from 10kΩ to 100k
Compact, multi-channel, electronic interface for PNS recording and stimulation
No full textA multi-channel system for neural signal recording/stimulation is presented. The system is split on two devices: an implantable High Voltage (HV) CMOS integrated circuit (IC) hosting a sigma delta modulator, together with a low noise preamplifier/prefilter and a digital platform for sigma delta decimation/control implemented on a FPGA. This innovative approach guarantees a robust communication link while minimizing the blocks to be implanted, saving power and area. The recording unit exhibits an IRN = 2.12uVrms in 800Hz-8kHz bandwidth, a programmable gain in the range 45.4dB-58dB and a 14-bit A/D conversion. The IC hosts also a current-mode stimulator able to deliver currents in the range of hundreds of microampere to electrodes with impedances up to 100kΩ
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