A Triple-Mode Performance-Optimized Reconfigurable Incremental ADC for Smart Sensor Applications

This paper proposes a triple-mode discrete-time incremental analog-to-digital converter (IADC) employing successive approximation register (SAR)-based zooming and extended counting (EC) schemes to achieve programmable trade-off capability of resolution and power consumption in various smart sensor applications. It mainly consists of an incremental delta???sigma modulator and the proposed SAR-EC sub-ADC for alternate operation of the coarse SAR conversion and EC. They can be reconfigured to operate separately depending on the application requirements. The SAR-based zooming structure allows the IADC to have better linearity and resolution, and additional activation of the EC function gives the further resolution. During this reconfigurable conversion process, pipelined reusing operation of sub-blocks reduces the silicon area and the number of cycles for target resolutions. A prototype ADC is fabricated in a 180-nm CMOS process, and its triple-mode operation of high-resolution, medium-resolution, and low-power is experimentally verified to achieve 116.1-, 109.4-, and 73.3-dB dynamic ranges, consuming 1.60, 1.26, and 0.39 mW, respectively

A Three-Step Resolution-Reconfigurable Hazardous Multi-Gas Sensor Interface for Wireless Air-Quality Monitoring Applications

This paper presents a resolution-reconfigurable wide-range resistive sensor readout interface for wireless multi-gas monitoring applications that displays results on a smartphone. Three types of sensing resolutions were selected to minimize processing power consumption, and a dual-mode front-end structure was proposed to support the detection of a variety of hazardous gases with wide range of characteristic resistance. The readout integrated circuit (ROIC) was fabricated in a 0.18 ??m CMOS process to provide three reconfigurable data conversions that correspond to a low-power resistance-to-digital converter (RDC), a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC), and a 16-bit delta-sigma modulator. For functional feasibility, a wireless sensor system prototype that included in-house microelectromechanical (MEMS) sensing devices and commercial device products was manufactured and experimentally verified to detect a variety of hazardous gases

CT-Guided Percutaneous Vertebroplasty in the Treatment of an Upper Thoracic Compression Fracture

Percutaneous vertebroplasty (PVP) has been used to relieve pain and to prevent further collapse of the vertebral body in patients with an osteoporotic compression fracture. The most commonly affected site for the use of PVP is the thoracolumbar junction. There are few reports that have described on the usefulness of PVP in the treatment of a high thoracic compression fracture. We report a case of an upper thoracic compression fracture that was treated with computed tomography (CT)-guided PVP. It was possible to obtain easy access to the narrow thoracic pedicle and it was also possible to monitor continuously the proper volume of polymethylmethacrylate employed, under CT guidance

Optical dispersion control in surfactant-free DNA thin films by vitamin B2 doping

A new route to systematically control the optical dispersion properties of surfactant-free deoxyribonucleic acid (DNA) thin solid films was developed by doping them with vitamin B2, also known as riboflavin. Surfactant-free DNA solid films of high optical quality were successfully deposited on various types of substrates by spin coating of aqueous solutions without additional chemical processes, with thicknesses ranging from 18 to 100 nm. Optical properties of the DNA films were investigated by measuring UV-visible-NIR transmission, and their refractive indices were measured using variable-angle spectroscopic ellipsometry. By doping DNA solid films with riboflavin, the refractive index was consistently increased with an index difference Δn ≥ 0.015 in the spectral range from 500 to 900 nm, which is sufficiently large to make an all-DNA optical waveguide. Detailed correlation between the optical dispersion and riboflavin concentration was experimentally investigated and thermo-optic coefficients of the DNA-riboflavin thin solid films were also experimentally measured in the temperature range from 20 to 85 °C, opening the potential to new bio-thermal sensing applications

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Department of Electrical EngineeringA gas monitoring system is needed to ensure the safety and evacuation of neighboring citizens from accidents in the chemical industrial complex. The gas sensor system has a fundamental problem that is affected by elements such as gas sensor aging, temperature, and humidity. This problem can be solved through gas sensor calibration, but it requires a lot of cost and time. To improve these problems of gas sensor systems, this paper presented an indirect gas response self-calibration and its gas sensor system for efficient operation. In addition, a gas ROIC that accommodate various gas sensors and optimize the performance of gas sensor system according to external circumstances were designed.ope

A Four-Step Incremental ADC Based on High-Coefficient Integrator and Binary Extended Counting With Capacitive DAC

This brief proposes a discrete-time four-step reconfigurable incremental ADC (IADC) which consists of a firststep SAR conversion, a second-step IADC operation, and double extended binary counting (EBC). While coarse conversion with the 8b SAR ADC is preceded, instead of 8b DAC, 7b capacitive DAC based integrator operation in the IADC becomes available to reduce the chip area and power consumption of amplifier. Additional resolution is achieved by performing the EBC twice, where its conversion time is reduced by using the binary operation with a 7b capacitive DAC. The IADC and the EBC are reconfigured to utilize the same sub-blocks of one amplifier and one comparator, thus reducing silicon area and obtaining high linearity. A prototype ADC is fabricated in a 180-nm CMOS process, and it achieves 179.7 dB FoM and consumes 176 ??W

A Triple-mode Reconfigurable Incremental SigmaDelta ADC with SAR-based Zooming and Extended Counting

This paper proposes a triple-mode discrete-time incremental sigma-delta ADC employing SAR-based zooming and extended counting for programmable resolutions. A SAR-based zooming structure allows the sigma-delta modulator to have better linearity and resolution, and also additional activation of extended counting function gives additional resolution. A prototype ADC is fabricated in a 180 nm CMOS process, and it achieves 111.9 dB, 106.6 dB, and 73.3 dB dynamic range for the triple mode consuming 1.60 mW, 1.26 mW, and 0.31 mW respectively

An Energy-efficient Multi-channel Dual-mode Wireless Gas-sensor System with Performance Regulation Capability

This paper presents the prototype of a wireless gas sensor system with real-time monitoring interface. A learning-based performance regulation scheme is proposed to improve the system efficiency. The scheme can adjust the pattern recognition, mode control and prediction of successive approximation register analog-to-digital converter (SAR ADC) results with neural network algorithm. The ROIC is supported 8-channel gas sensors and multi-mode as monitoring mode and precision mode. In order to optimize the power consumption of precision mode further, auto controlled correlated double sampling (CDS) zooming is proposed in the ROIC. Thus, the system can optimize the required resolution and power consumption depending on the critical level of each gas type and concentration. The prototype ROIC was fabricated with CMOS technology and 15.8x efficiency improvement of the system were verified experimentally through real gas sensing

XGBoost based machine learning approach to predict the risk of fall in older adults using gait outcomes

Abstract This study aimed to identify the optimal features of gait parameters to predict the fall risk level in older adults. The study included 746 older adults (age: 63–89 years). Gait tests (20 m walkway) included speed modification (slower, preferred, and faster-walking) while wearing the inertial measurement unit sensors embedded in the shoe-type data loggers on both outsoles. A metric was defined to classify the fall risks, determined based on a set of questions determining the history of falls and fear of falls. The extreme gradient boosting (XGBoost) model was built from gait features to predict the factor affecting the risk of falls. Moreover, the definition of the fall levels was classified into high- and low-risk groups. At all speeds, three gait features were identified with the XGBoost (stride length, walking speed, and stance phase) that accurately classified the fall risk levels. The model accuracy in classifying fall risk levels ranged between 67–70% with 43–53% sensitivity and 77–84% specificity. Thus, we identified the optimal gait features for accurate fall risk level classification in older adults. The XGBoost model could inspire future works on fall prevention and the fall-risk assessment potential through the gait analysis of older adults