1,720,994 research outputs found
A microcontrolled neural interface with electrode impedance measurement
No full textAn electronic interface for neural recording, Peripheral Neural System (PNS) stimulation and electrode impedance measurement is presented. The device can be connected to the computer by an USB link and is controlled by a Graphical User Interface (GUI). The system is composed by an analog unit and by a digital module for data acquisition and system configuration. Two microcontrollers allow to configure the system in different operating modes and to set stimulation/recording parameters. The experimental results show that the designed system is able to filter and amplify signals in the [950Hz-2kHz] bandwidth, to generate current stimulation pulses with software programmable amplitude, width and frequency and to measure in-vivo the impedance of the electrode
A Front-End stage for neural signal recording based on a sigma delta modulator
No full textA new device for peripheral neural signals recording is presented. The designed system is composed by an analog and a digital part. The analog part, to be integrated on an implantable CMOS chip, is kept as simple as possible and hosts a low noise first order pre-amplifier/pre-filtering stage that provides a 46dB gain in the bandwidth 800Hz-7.2kHz and a 16-bit 3rd order sigma delta modulator. A highly selective band-pass filter is implemented into the digital domain, incorporated in the decimator block of the sigma-delta converter; in this way it is possible to reduce total area (which is 0.4mm 2 for a single input channel) and power consumption (250μW, single channel) in the integrated, implantable module. Simulation results prove the capability of the proposed system to record signals whose magnitude is in the order of tens of microvolts thanks to the low Input Referred Noise (IRN) of 2.4μV rms of the input stage
A PCB system implementation for neural signals recording and PNS stimulation
No full textA bidirectional interface for neural recording and stimulation is proposed. The recording circuitry eliminates the outband interferences thanks to a high selective band pass filter in the 1:1kHz-2kHz band, providing a gain of 24dB. Further amplification is obtained by means of a programmable gain amplifier that can bring the gain to 44dB. The signal is then digitalized with a 16 bit ADC and sent to a microcontroller. In order to minimize the input referred noise, the whole signal acquisition chain has been designed with a Fully Differential approach, by this way an IRN of 364nV has been achieved. Stimulation signals are biphasic current pulses with programmable duration, frequency and amplitude. These patterns are generated by a DAC followed by a Voltage to Current converter. The programmability of the pulse parameters is guaranteed by the microcontroller: the current amplitude can range from 5μA to 20μA, the pulse duration varies from 50μs to 150μs while the frequency can cover from 10Hz to 400Hz. The system has been implemented in a PCB and successfully tested with a pre-recorded neural signal extracted by the peripheral nervous system of a rabbit with a tfLIFE electrode
A CMOS biocompatible charge detector for biosensing applications
No full textA solid-state CMOS device capable of detecting the changes of electric charge caused by a chemical or biological reaction is presented. The device is fully compatible with a standard CMOS process. Bio-compatibility is obtained by passivation of the active area with a layer of alumina obtained with a simple, low-cost and reliable process. A test chip hosting 80 sensors has been realized and characterized showing the detection capabilities of the novel sensor. Re-usability of the device by stripping of the alumina layer was proved
Design of a Programmable Bioelectrical Impedance System for Biomedical Applications
No full textThe design of a portable,versatile and programmable bioelectrical impedance system is presented. The device uses in expensive off-the-shelf components to perform multi-frequency current injection and voltage measurements through skin electrodes. The impedance measurement system can be configured as multi-frequency bioelectrical impedance analyzer as well as acupuncture point detector, for localizing pathologically changed acupuncture points on the body. In order to improve the accuracy and the flexibility of the measurements, a programmable wide frequency band width current source has been designed. It allows to generate sinusoidal and square wave forms with a frequency up to 1 MHz and amplitude values in the range of [12 mu A(pp)-1.2mA(pp)]. The measured signals can be amplified with a programmable gain and converted with 16 bits of resolution before being transmitted to a PC through USB transmission for further processing
A Microcontrolled Constant Current Source for Wideband Bioimpedance Measurements
No full textWe describe a programmable wide frequency bandwidth current source realized using a COTS-based (Commercial Off-the-Shelf) design. It is capable of injecting sinusoidal, square or triangle current waveforms of amplitude ranging from 12μApp to 1.2mApp and frequency up to 1MHz, into the human body through a pair of electrodes. The device is controlled by a graphic user-friendly interface, which allows users to monitor data transmission and acquisition as well as to set current injection parameters. In addition to current injection, the system is meant for sensing in real time the resulting response. The measured voltage drop across tissue impedance can be amplified with a programmable gain and converted into digital values with 10 bits of resolution before being transmitted to a PC through USB transmission for further processin
An electronic interface for neural recording and stimulation
No full textA portable neural activity acquisition and stimulation system by means of tfLIFE implantable electrodes has been realized. The detecting circuit provides: a selective filtering made up of a 4th order high pass Multiple Feedback filter (f-3dB = 1.1 kHz) and a 4th order low pass Multiple Feedback filter (f-3dB = 2kHz), a variable gain (24dB - 44dB) and a 16 bit analog to digital conversion. The stimulator allows to generate specific electrical signals through a digital-to-analog converter while stimulation parameters as frequency, duration and intensity are controlled by a digital microcontroller. Simulation results and first experimental results of the interface demonstrate how neural signals of a few of microvolts can be filtered, programmable amplified and digitalized without distortion
A CMOS integrated circuit for DNA hybridization detection with digital output and temperature control
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