Continuous monitoring of fluid status through bio-impedance (Bio-Z) measurement of thoracic magnitude or phase is critical in reducing the mortality of chronic heart failure (CHF) patients. However, the stringent power constraints of implantable devices force the design of Bio-Z sensors to be highly challenging. We present a sub-10- $\mu \text{W}$ Bio-Z sensor IC operating from a 0.5 V-supply, sustaining a sub-1° of phase error even under 10% of supply and 0 °C–70 °C of temperature variations. Fabricated in a 65-nm CMOS process, this sensor IC exhibits a 15.28- $\text{m}\Omega /\surd $ Hz of input-referred impedance noise performance, occupying a 4.83 mm². Its linearity performance shows that the magnitude and the phase of Bio-Z can be measured within the error of 2% and 0.4°, respectively, given that the magnitude of load impedance is less than 126 $\Omega $ , and thus, it is suitable for fluid status monitoring applications. Experimental measurement on the human chest demonstrates its capabilities of thoracic impedance variance (TIV) and impedance cardiography (ICG) monitoring.

中文翻译：

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具有低于 1° 相位误差的 0.5V 低于 10μW 15.28mΩ/√Hz 生物阻抗传感器 IC

通过胸部幅度或相位的生物阻抗 (Bio-Z) 测量连续监测液体状态对于降低慢性心力衰竭 (CHF) 患者的死亡率至关重要。然而，可植入设备严格的功率限制迫使 Bio-Z 传感器的设计极具挑战性。我们提出了一个子 10- $\mu \text{W}$ Bio-Z 传感器 IC 由 0.5 V 电源供电，即使在 10% 的电源和 0 °C–70 °C 的温度变化下也能保持低于 1° 的相位误差。该传感器 IC 采用 65 纳米 CMOS 工艺制造，具有 15.28- $\text{m}\Omega /\surd $ Hz 的输入参考阻抗噪声性能，占用 4.83 mm ²。其线性性能表明，在负载阻抗幅值小于 126 的情况下，Bio-Z 的幅值和相位可分别测量在 2% 和 0.4° 的误差范围内 $\欧米茄 $ ，因此，它适用于流体状态监测应用。人体胸部的实验测量证明了其胸廓阻抗方差 (TIV) 和阻抗心电图 (ICG) 监测的能力。