Low-voltage silicon(Si)-based light-emitting diode(LED) is designed based on the former research of LED in Si-based standard complementary metal oxide semiconductor(CMOS) technology.The low-voltage LED is designed under the research of cross-finger structure LEDs and sophisticated structure enhanced LEDs for high efficiency and stable light source of monolithic chip integration.The device size of low-voltage LED is 45.85×38.4(μm),threshold voltage is 2.2 V in common condition,and temperature is 27 ℃.The external quantum efficiency is about 10-6 at stable operating state of 5 V and 177 mA.
This paper presents a third-order single-loop delta-sigma modulator of a biomedical micro-system for portable electroencephalogram(EEG) monitoring applications.To reduce the power consumption,the loop filter of the proposed modulator is implemented by applying a switched-capacitor structure.The modulator is designed in a 0.35-μm 2P4M standard CMOS process,with an active area of 365×290μm^2.Experimental results show that this modulator achieves a 68 dB dynamic range with an input sinusoidal signal of 100 Hz signal bandwidth under a 64 over-sampling ratio.The whole circuit consumes 515μW under a 2.5 V power supply,which is suitable for portable EEG monitoring.
A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology.This device is capable of versatile working modes:it can emit visible to near infra-red (NIR) light (the spectrum ranges from 500 nm to 1000 nm) in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light (the spectrum ranges from 900 nm to 1300 nm) in the forward injection mode with working voltage below 2 V.An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode.Furthermore,when the gate oxide is broken down,NIR light is emitted from the polysilicon/oxide/silicon structure.Optoelectronic characteristics of the device working in different modes are measured and compared.The mechanisms behind these different emissions are explored.
TiN,platinum (Pt) black and iridium oxide are introduced to the stimulating sites to improve the performance of the flexible electrode.Low temperature process is used to fabricate the modifying films.TiN is coated on the gold sites by magnetron sputtering while platinum black and iridium oxide are coated by electroplating and electrodeposition,respectively.The im-pedance of the electrode decreases dramatically after modification.The combined analysis of surface morphology and cyclic voltammograms (CV) in phosphate buffer saline (PBS) solution indicates that the modified electrode sites have larger elec-trode-electrolyte capacitance and smaller faradic resistance than unmodified sites,thus they have smaller electrochemical im-pedances.
LI XiaoQianPEI WeiHuaTANG RongYuGUI QiangGUO KaiWANG YuCHEN HongDa
A fully-differential bandpass CMOS(complementary metal oxide semiconductor) preamplifier for extracellular neural recording is presented.The capacitive-coupled and capacitive-feedback topology is adopted.The preamplifier has a midband gain of 20.4 dB and a DC gain of 0.The -3 dB upper cut-off frequency of the preamplifier is 6.7 kHz.The lower cut-off frequency can be adjusted for amplifying the field or action potentials located in different bands. It has an input-referred noise of 8.2μVrms integrated from 0.15 Hz to 6.7 kHz for recording the local field potentials and the mixed neural spikes with a power dissipation of 23.1μW from a 3.3 V supply.A bandgap reference circuitry is also designed for providing the biasing voltage and current.The 0.22 mm^2 prototype chip,including the preamplifier and its biasing circuitry,is fabricated in the 0.35-μm N-well CMOS 2P4M process.
In this paper,a silicon-based neural probe with microfluidic channels was developed and evaluated.The probe can deliver chemicals or drugs to the target neurons while simultaneously recording the electrical action of these neurons extracellularly.The probe was fabricated by double-sided deep reactive ion etching(DRIE) from a silicon-on-insulator(SOI) wafer.The flu-idic channels were formed with V-shape groove etching on the silicon probe and sealed with silicon nitride and parylene-C.The shank of the probe is 4 mm long and 120 μm wide.The thickness of the probe is 100 μm.The probe has two fluidic chan-nels and two recording sites.The microfluidic channels can withstand a pressure drop as much as 30 kPa and the flow resistiv-ity of the microfluidic channel is 0.13 μL min-1 kPa-1.The typical impedance of the neural electrode is 32.3 kΩ at 1 kHz at room temperature.
GUO Kai PEI WeiHua LI XiaoQian GUI Qiang TANG RongYu LIU Jian CHEN HongDa
