Automatic Drift Cancellation of Implanted Bladder Pressure Sensor.
Automatic Drift Cancellation of Implanted Bladder Pressure Sensor.
复制标题
植入式膀胱压力传感器的自动漂移消除。
DOI：
10.1109/biocas.2015.7348430
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Damaser,MargotS
中科院分区：
文献类型：
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作者：
Majerus,Steve;Damaser,MargotS
由于大气变化、包装吸湿和患者因素（如姿势、植入物移位和组织过度生长），植入式压力传感器会遭受长期偏移漂移。传统上，宽动态范围仪表用于满足给定应用的满量程和灵敏度要求。额外比特的传输大大增加了植入式医疗设备的功率消耗，并且简单的AC耦合不能监测静压。我们提出了一种混合信号失调消除环路，以最大限度地提高仪表电路的交流动态范围。数字实现允许设计人员控制消除系统的时间常数，并专门为功率门控压力传感器设计。压力偏移通过数字积分计算，具有粗/微调的双极IDAC将偏移消除电流注入标准压阻式MEMS压力传感器。测试结果表明，使用动态偏移消除，对于使用8位仪器的11位有效感测范围，动态范围增加了2.9位。系统的测量阶跃响应显示出2.3-3.8 mHz的整体高通响应。因此，该方法与具有非常慢的生理响应的器官（例如膀胱）中的压力的生物感测相关。
Implanted pressure sensors suffer from long-term offset drift due to atmospheric changes, package moisture absorption, and patient factors such as posture, implant shift, and tissue overgrowth. Traditionally, wide dynamic range instrumentation is used to satisfy the full-scale and sensitivity requirements for a given application. Transmission of extra bits greatly increases the power draw of an implanted medical device, and simple AC-coupling cannot monitor static pressures. We present a mixed-signal offset cancellation loop to maximize the AC dynamic range of instrumentation circuitry. A digital implementation allows for designer control of the cancellation system time constant and was specifically designed for power-gated pressure sensors. Pressure offset is calculated by digital integration and a bipolar IDAC with coarse/fine tuning injects an offset-cancelling current into a standard piezoresistive MEMS pressure sensor. Test results showed a dynamic range increase of 2.9 bits using dynamic offset cancellation, for an effective sensing range of 11 bits using 8-bit instrumentation. The measured step response of the system showed an overall highpass response of 2.3-3.8 mHz. This approach is therefore relevant for bio-sensing of pressures in organs with a very slow physiologic response, e.g. the bladder.