ABSTRACT Low power n-channel fully depleted local-SOI FinFET integrated sensors have been develop... more ABSTRACT Low power n-channel fully depleted local-SOI FinFET integrated sensors have been developed and validated for the amplification of pH sensing signals. A simple architecture with one FinFET connected as depletion-mode load and another one as driving sensor, provides a maximum readout gain of 6.6 V/V with a maximum pH readout sensitivity of 185 mV/pH, at 2 V operation. By comparing the proposed amplifier with a single sensing FinFET the threshold voltage shift readout is shown to be 4.4 times larger. High-k dielectric HfO2 has been used to maximize both sensing and electronic performances. The FinFETs have been fabricated on bulk silicon by a local-SOI technique. FinFET thickness (TFin) and height (HFin) achieved are in the range of 20 nm ≤ T Fin ≤ 40 nm and 65 nm ≤ HFin ≤ 120 nm.
2009 4th International IEEE/EMBS Conference on Neural Engineering (NER 2009), 2009
ABSTRACT We use a planar, CMOS-based microelectrode array (MEA) featuring 3,150 metal electrodes ... more ABSTRACT We use a planar, CMOS-based microelectrode array (MEA) featuring 3,150 metal electrodes per mm2 and 126 recording channels to record spatially highly resolved extracellular action potentials (EAPs) from Purkinje cells (PCs) in acute cerebellar slices. An Independent-Component-Analysis-based (ICA) spike sorter is used to reveal EAPs of single cells at subcellular resolution. Those EAPs are then used to set up a compartment model of a PC. The model is used to make and finetune estimations of the distance between MEA surface and PC soma. This distance is estimated using the amplitude-independent part of the shape of the EAPs obtained from recordings. The estimation shows that, in our preparations, we can record from PCs with the center of their soma at approximately 35 mum and 90 mum vertical distance to the chip surface.
ABSTRACT Two different silicon nanowire (SiNW) based devices are discussed as potential ion and b... more ABSTRACT Two different silicon nanowire (SiNW) based devices are discussed as potential ion and biological sensors. Three-dimensional TCAD simulations are used to investigate and compare the efficiency of such devices upon applying an external voltage difference of ΔVg = 50 mV. The simulation results presented in this work reveal that an n-doped shell acts as sensitivity booster for uniformly doped SiNWs. It is demonstrated that a 10 nm n-type shell surrounding a p-type core can produce a sensitivity enhancement of more than 50%.
We report on a compact (0.02 mm(2) ) buffer for both voltage and current stimulation of electroge... more We report on a compact (0.02 mm(2) ) buffer for both voltage and current stimulation of electrogenic cells on a complementary metal-oxide semiconductor microelectrode array. In voltage mode, the circuit is a high-current class-AB voltage follower, based on a local common-mode feedback (LCMFB) amplifier. In current mode, the circuit is a current conveyor of type II, using the same LCMFB amplifier with cascode stages to increase the gain. The circuit shows good linearity in the 0.5-3.5 V input range and has extensively been used for stimulation of neuronal cultures.
We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system compri... more We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I-V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized ...
ABSTRACT Low power n-channel fully depleted local-SOI FinFET integrated sensors have been develop... more ABSTRACT Low power n-channel fully depleted local-SOI FinFET integrated sensors have been developed and validated for the amplification of pH sensing signals. A simple architecture with one FinFET connected as depletion-mode load and another one as driving sensor, provides a maximum readout gain of 6.6 V/V with a maximum pH readout sensitivity of 185 mV/pH, at 2 V operation. By comparing the proposed amplifier with a single sensing FinFET the threshold voltage shift readout is shown to be 4.4 times larger. High-k dielectric HfO2 has been used to maximize both sensing and electronic performances. The FinFETs have been fabricated on bulk silicon by a local-SOI technique. FinFET thickness (TFin) and height (HFin) achieved are in the range of 20 nm ≤ T Fin ≤ 40 nm and 65 nm ≤ HFin ≤ 120 nm.
2009 4th International IEEE/EMBS Conference on Neural Engineering (NER 2009), 2009
ABSTRACT We use a planar, CMOS-based microelectrode array (MEA) featuring 3,150 metal electrodes ... more ABSTRACT We use a planar, CMOS-based microelectrode array (MEA) featuring 3,150 metal electrodes per mm2 and 126 recording channels to record spatially highly resolved extracellular action potentials (EAPs) from Purkinje cells (PCs) in acute cerebellar slices. An Independent-Component-Analysis-based (ICA) spike sorter is used to reveal EAPs of single cells at subcellular resolution. Those EAPs are then used to set up a compartment model of a PC. The model is used to make and finetune estimations of the distance between MEA surface and PC soma. This distance is estimated using the amplitude-independent part of the shape of the EAPs obtained from recordings. The estimation shows that, in our preparations, we can record from PCs with the center of their soma at approximately 35 mum and 90 mum vertical distance to the chip surface.
ABSTRACT Two different silicon nanowire (SiNW) based devices are discussed as potential ion and b... more ABSTRACT Two different silicon nanowire (SiNW) based devices are discussed as potential ion and biological sensors. Three-dimensional TCAD simulations are used to investigate and compare the efficiency of such devices upon applying an external voltage difference of ΔVg = 50 mV. The simulation results presented in this work reveal that an n-doped shell acts as sensitivity booster for uniformly doped SiNWs. It is demonstrated that a 10 nm n-type shell surrounding a p-type core can produce a sensitivity enhancement of more than 50%.
We report on a compact (0.02 mm(2) ) buffer for both voltage and current stimulation of electroge... more We report on a compact (0.02 mm(2) ) buffer for both voltage and current stimulation of electrogenic cells on a complementary metal-oxide semiconductor microelectrode array. In voltage mode, the circuit is a high-current class-AB voltage follower, based on a local common-mode feedback (LCMFB) amplifier. In current mode, the circuit is a current conveyor of type II, using the same LCMFB amplifier with cascode stages to increase the gain. The circuit shows good linearity in the 0.5-3.5 V input range and has extensively been used for stimulation of neuronal cultures.
We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system compri... more We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I-V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized ...
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Papers by Paolo Livi