Jaehyuk Lee

A 10.4 mW electrical impedance tomography SoC for portable real-time lung ventilation monitoring system

An electrical impedance tomography (EIT) SoC is proposed for the portable real-time lung ventilation monitoring system. The proposed EIT SoC is integrated into belt-typefabric system with 32 electrodes and can show the dynamic images of the lung ventilation on the mobile devices. To get high fidelity images, a T-switch is adopted for high off-isolation between electrodes more than 60 dB, and I/Q signal generation and demodulation can obtain both real and imaginary part of images. For the real-time imaging, an on-chip fast demodulation scheme is proposed, and it can also reduce speed requirements of ADC for low-power consumption. The proposed EIT SoC of 5.0 mm × 5.0 mm is fabricated in 0.18 μm CMOS technology, and consumes only 10.4 mW with 1.8 V supply. As a result, EIT images were reconstructed with 97.3% of accuracy and up to 20 frames/s real-time lung images can be displayed on the mobile devices.

An 87-

In this paper, we present an iontophoresis controller IC with real-time monitoring of total injected charge quantity and skin condition. The proposed IC contains 32-level programmable current stimulator, a temperature sensor and a dual impedance sensor to monitor skin temperature, contact and tissue impedances. The measured temperature and impedances, related with the skin condition, are used for adaptive charge injection by modifying the current stimulation levels through the real-time feedback path. An implemented fabric patch type drug delivery system provides up to 87mA-min dosage larger than the dosage range (80mA-min) of commercial iontophoresis patches [4].

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The wearable lung-health monitoring system is proposed with an electrical impedance tomography (EIT). The proposed system has light belt-type form factor which is implemented with the EIT integrated circuit (IC) on the planar-fashionable circuit board (P-FCB) technology. The EIT IC provides programmable current stimulation which is optimally controlled by the results of contact impedance monitoring. The measured data is transmitted to the mobile device and the lung EIT images are reconstructed and displayed with up to 20 frames/s real-time. From the lung EIT image, the measured lung air volume ratio can be used as an indicator of the lung-health, and other various parameters can be extracted to monitor lung status. The proposed wearable system achieves the user convenience for lung-health monitoring which can be used personally at home. The proposed system is fully implemented and verified on both in-vitro and in-vivo tests.

Iontophoresis Controller IC With Dual-Mode Impedance Sensor for Patch-Type Transdermal Drug Delivery System

An electrical impedance tomography (EIT) SoC is proposed for the portable real-time lung ventilation monitoring system. The proposed EIT SoC is integrated into belt-typefabric system with 32 electrodes and can show the dynamic images of the lung ventilation on the mobile devices. To get high fidelity images, a T-switch is adopted for high off-isolation between electrodes more than 60 dB, and I/Q signal generation and demodulation can obtain both real and imaginary part of images. For the real-time imaging, an on-chip fast demodulation scheme is proposed, and it can also reduce speed requirements of ADC for low-power consumption. The proposed EIT SoC of 5.0 mm × 5.0 mm is fabricated in 0.18 µm CMOS technology, and consumes only 10.4 mW with 1.8 V supply. As a result, EIT images were reconstructed with 97.3% of accuracy and up to 20 frames/s real-time lung images can be displayed on the mobile devices.

Wearable lung-health monitoring system with electrical impedance tomography.

There has been recent research into continuous monitoring of the quantitative anesthesia (ANES) depth level for safe surgery [1]. However, the current ANES depth monitoring approach, bispectral index (BIS) [3], uses only EEG from the frontal lobe, and it shows critical limitations in the monitoring of ANES depth such as signal distortion due to electrocautery, EMG and dried gel, and false response to the special types of anesthetic drugs [3]. Near-infrared spectroscopy (NIRS) is complementary to EEG [2], and can not only compensate for the distorted depth level, but also assess the effects of various anesthetic drugs. In spite of its importance, a unified ANES monitoring system using EEG/NIRS together has not been reported because NIRS signals have widely different dynamic ranges (10pA to 10nA), and also signal level variations from person to person and environment are not manageable without closed-loop control (CLC).

A 10.4 mW Electrical Impedance Tomography SoC for Portable Real-Time Lung Ventilation Monitoring System

Electrical impedance tomography (EIT) has been studied to monitor lung ventilation because it is the only real-time lung imaging method without large equipment [1–2]. However, previous EIT systems just provided 2D cross-sectional image with limited spatial information of the lung and unneglectable volume detection error depending on the location of 2D EIT belt relative to the patients lung. In spite of its importance, the 3D-EIT has not been realized in lung monitoring because it has many design challenges such as noises incurred by complicated wiring, long cable length, wide variation in electrode contact and signal, and large personal-to-person impedance variation. In this paper, we present a portable 3D-EIT SoC for real-time lung ventilation monitoring with following 5 features: 1) The active electrodes (AEs) system to reduce coupling noise, 2) High output impedance current stimulator to inject stable current, 3) Impedance spectroscopy to enable both time-difference (TD) EIT and frequency-difference (FD) EIT, and to select an optimal frequency for TD-EIT, 4) Wide-dynamic range front-end circuit to detect variable ranges of signal with high-input impedance and CMRR, 5) Calibration to reduce the electrical characteristics variations of AEs.

27.2 A 25.2mW EEG-NIRS multimodal SoC for accurate anesthesia depth monitoring

This paper presents a low power, high resolution bio-impedance sensor IC for respiration monitoring application. It contains the dual path instrumentation amplifier (DPIA) including current reusing transconductance amplifier and high gain transimpedance amplifier for high resolution, low power and wide input range bio-impedance measurement. Measured results show that the proposed readout circuit has 354 nVrms input noise and 2.12 μW of the lowest power consumption along with the widest differential input range of 52 mVpp as well. As a result, the readout circuit enables bio-impedance sensor IC to uphold a comparable 38.51 mΩrms impedance resolution with a relatively smaller 26 μApp injection current than previous works. This leads to a 24 μW of lowest overall power consumption of bio-impedance sensor. In this sense, the proposed bio-impedance sensor IC achieves its figure of merit (FoM) by value that is 4 times lower compared to the state-of-the-art.

21.2 A 1.4mΩ-sensitivity 94dB-dynamic-range electrical impedance tomography SoC and 48-channel Hub SoC for 3D lung ventilation monitoring system

A sticker-type system with hybrid integration of CMOS IC and organic optical sensors is proposed to monitor photoplethysmogram (PPG) signals. To solve problems with the previous solely organic sensor-based works, CMOS IC is implemented in 180 nm technology under 5 V/1.5 V dual power supply. The silver-wire printed planar-fashionable circuit board (P-FCB) is used to connect the CMOS IC with organic sensors. The proposed hybrid system has the five following key features: 1) Power-efficient structure of organic sensor; 2) Integrated analog front-end and digital processor; 3) Degradation compensation scheme; 4) Large parasitic elements optimized design; and 5) Motion artifact rejection scheme. The sticker-type PPG monitoring system has mass of only 2g, including the batteries, and consumes only

A 24 μW 38.51 mΩ rms resolution bio-impedance sensor with dual path instrumentation amplifier

233~mu text{W}

Sticker-Type Hybrid Photoplethysmogram Monitoring System Integrating CMOS IC With Organic Optical Sensors

to operate. The PPG signal could be acquired from various body parts (finger, wrist, and neck). The peripheral oxygen saturation level (SpO2 extraction results are verified by comparison with a commercial sensor device.