Title :
A Low-Power/Low-Voltage CMOS Wireless Interface at 5.7 GHz With Dry Electrodes for Cognitive Networks
Author :
Dias, Nuno Sérgio ; Carmo, João Paulo ; Mendes, Paulo Mateus ; Correia, José Higino
Author_Institution :
Dept. of Ind. Electron., Univ. of Minho, Guimaraes, Portugal
fDate :
3/1/2011 12:00:00 AM
Abstract :
This paper describes a low-power/low-voltage CMOS wireless interface (CMOS-WiI) at 5.7 GHz with dry electrodes for congnitive networks. The electrodes are 4 X4 microtip arrays and acquire electroencephalogram (EEG) signals in key- points for processing. The CMOS-WiI was fabricated in a UMC 0.18 μm RF CMOS process and its total power consumption is 23 mW with a voltage-supply of only 1.5 V. The carrier frequency is digitally selectable and it can be one of 16 possible values in the range 5.42-5.83 GHz, with 27.12 MHz steps. These multiple carriers allow a better spectrum allocation as well as the acquisition, processing and transmission of high-quality EEG signals from 16 electrode arrays. The microtips array was fabricated through bulk micromachining of a 〈100 〉-type silicon substrate in a potassium hydroxide solution and avoids long subject preparations for EEG data acquisition. The reactive sputtering of iridium dioxide (IrO) on the surface of the array guarantees its biocompatibility. The fabrication process was trimmed in a way that each microtip presents solid angles of 54.7° , a width in the range 150-200 μm, a height of 100-200 μm, and a microtip interspacing of 2 μm. The microtips array coated with IrO together with the CMOS-WiI permit the remote monitoring of EEG signals from freely-moving subjects.
Keywords :
CMOS integrated circuits; biomedical electrodes; biomedical electronics; cognitive systems; electroencephalography; learning systems; medical computing; microwave integrated circuits; patient monitoring; wireless sensor networks; CMOS wireless interface; EEG data acquisition; EEG signals; RF CMOS process; biocompatibility; cognitive network; dry electrode; electroencephalogram signal; frequency 5.42 GHz to 5.83 GHz; microtip arrays; power 23 mW; reactive sputtering; size 0.18 mum; size 100 mum to 200 mum; spectrum allocation; voltage 1.5 V; wireless sensors networks; Sensor interface; wireless microsystems; wireless sensors networks;
Journal_Title :
Sensors Journal, IEEE
DOI :
10.1109/JSEN.2010.2067447