Showing papers by "Tom Torfs published in 2011"

A 30 $\mu$ W Analog Signal Processor ASIC for Portable Biopotential Signal Monitoring

Abstract: This paper presents the design and implementation of an analog signal processor (ASP) ASIC for portable ECG monitoring systems The ASP ASIC performs four major functionalities: 1) ECG signal extraction with high resolution, 2) ECG signal feature extraction, 3) adaptive sampling ADC for the compression of ECG signals, 4) continuous-time electrode-tissue impedance monitoring for signal integrity monitoring These functionalities enable the development of wireless ECG monitoring systems that have significantly lower power consumption yet that are more capable than their predecessors The ASP has been implemented in 05 μm CMOS process and consumes 30 μW from a 2 V supply The noise density of the ECG readout channel is 85 nV/√Hz and the CMRR is better that 105 dB The adaptive sampling ADC is capable of compressing the ECG data by a factor of 7 and the heterodyne chopper readout extracts the features of the ECG signals Combination of these two features leads to a factor 4 reduction in the power consumption of a wireless ECG monitoring system Furthermore, the proposed continuous-time impedance monitoring circuit enables the monitoring of the signal integrity

Low power wireless sensor network for building monitoring

Abstract: A wireless sensor network is proposed for monitoring buildings to assess earthquake damage. The sensor nodes use custom-developed capacitive MEMS strain and 3D acceleration sensors and a low power readout ASIC for a battery life of up to 12 years. The strain sensors are mounted at the base of the building to measure the settlement and plastic hinge activation of the building after an earthquake. They measure periodically or on-demand from the base station. The accelerometers are mounted at every floor of the building to measure the seismic response of the building during an earthquake. They record during an earthquake event using a combination of the local acceleration data and remote triggering from the base station based on the acceleration data from multiple sensors across the building. A low power network architecture was implemented over an 802.15.4 MAC in the 900MHz band. A custom patch antenna was designed in this frequency band to obtain robust links in real-world conditions.

CMOS-Based High-Density Silicon Microprobe Arrays for Electronic Depth Control in Intracortical Neural Recording

Abstract: This paper reports on a novel high-density CMOS-based silicon microprobe array for intracortical recording applications. In contrast to existing systems, CMOS multiplexing units are integrated directly on the slender, needle-like probe shafts. Single-shaft probes and four-shaft combs have been realized with 188 and 752 electrodes, respectively, with a pitch of 40 μm arranged in two columns along 4-mm-long probe shafts. Rather than performing a mechanical translation of the probe shaft relative to the brain tissue to optimize the distance between electrodes and neurons, the electrode position is adjusted by electronically switching between the different electrodes along the shaft. The paper presents the probe concept, the CMOS circuitry design, the applied post-CMOS fabrication process, and the assembled probe systems.

Two-Dimensional Multi-Channel Neural Probes With Electronic Depth Control

Abstract: This paper presents multi-electrode arrays for in vivo neural recording applications incorporating the principle of electronic depth control (EDC), i.e., the electronic selection of recording sites along slender probe shafts independently for multiple channels. Two-dimensional (2D) arrays were realized using a commercial 0.5- μm complementary-metal-oxide-semiconductor (CMOS) process for the EDC circuits combined with post-CMOS micromachining to pattern the comb-like probes and the corresponding electrode metallization. A dedicated CMOS integrated front-end circuit was developed for pre-amplification and multiplexing of the neural signals recorded using these probes.

Ultra-Thin Chip Package (UTCP) and stretchable circuit technologies for wearable ECG system

Abstract: A comfortable, wearable wireless ECG monitoring system is proposed. The device is realized using the combination of two proprietary advanced technologies for electronic packaging and interconnection : the UTCP (Ultra-Thin Chip Package) technology and the SMI (Stretchable Mould Interconnect) technology for elastic and stretchable circuits. Introduction of these technologies results in small fully functional devices, exhibiting a significant increase in user comfort compared to devices fabricated with more conventional packaging and interconnection technologies.

Optimized R peak detection algorithm for ultra low power ECG systems

Abstract: In this paper, an optimized R peak detection algorithm with a high level of accuracy that can be implemented using very low power consumption is proposed. The accuracy of the algorithm is evaluated against the MIT-BIH arrhythmia database, giving an average sensitivity of 99.22% and positive predictivity of 99.86%, as well as against imec's database with ambulatory data, giving an average sensitivity of 99.77% and positive predictivity of 99.82%. The power consumption of the algorithm is estimated by implementation in a commercial low power microcontroller (TI MSP430) to 71.42 µW. The algorithm has been tested in a hardware system using applied signals at varying signal to noise ratio as well as on human volunteers.

Laboratory validation of MEMS-based sensors for post-earthquake damage assessment

Abstract: The EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration. These integrate Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package; which can be incorporated in reinforced concrete buildings and can transmit data using a wireless interface. During the first phase of the project, sensor prototypes were produced by assembling preexisting components. In the second phase we developed miniaturized MEMS prototypes fulfilling the target application requirements. This paper outlines the accelerometer operating principles and the sensor architecture, and illustrates operation at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance.

Structured probes for neural applications

Abstract: A probe for recording and/or stimulating brain activity includes a connecting portion and at least one shank extending from the connecting portion. The at least one shank includes a first side, a second side opposed to the first side, and a fin protruding substantially perpendicularly from the second side and running on at least a part of a length of the at least one shank. The first side includes at least one recording and/or stimulating site.