Kim Albert, Powell Charles R, Ziaie Babak
School of Electrical and Computer Engineering, Purdue University, 1205 W. State St, West Lafayette, IN, 47907, USA.
Birck Nanotechnology Center, Purdue University, 1205 W. State St, West Lafayette, IN, 47907, USA.
Biomed Microdevices. 2016 Apr;18(2):32. doi: 10.1007/s10544-016-0058-y.
Monitoring bodily pressures provide valuable diagnostic and prognostic information. In particular, long-term measurement through implantable sensors is highly desirable in situations where percutaneous access can be complicated or dangerous (e.g., intracranial pressure in hydrocephalic patients). In spite of decades of progress in the fabrication of miniature solid-state pressure sensors, sensor drift has so far severely limited their application in implantable systems. In this paper, we report on a universal packaging technique for reducing the sensor drift. The described method isolates the pressure sensor from a major source of drift, i.e., contact with the aqueous surrounding environment, by encasing the sensor in a silicone-filled medical-grade polyurethane balloon. In-vitro soak tests for 100 days using commercial micromachined piezoresistive pressure sensors demonstrate a stable operation with the output remaining within 1.8 cmH2O (1.3 mmHg) of a reference pressure transducer. Under similar test conditions, a non-isolated sensor fluctuates between 10 and 20 cmH2O (7.4-14.7 mmHg) of the reference, without ever settling to a stable operation regime. Implantation in Ossabow pigs demonstrate the robustness of the package and its in-vivo efficacy in reducing the baseline drift.
监测身体压力可提供有价值的诊断和预后信息。特别是，在经皮接入可能复杂或危险的情况下（例如脑积水患者的颅内压），通过植入式传感器进行长期测量非常必要。尽管在微型固态压力传感器的制造方面取得了数十年的进展，但迄今为止，传感器漂移严重限制了它们在植入式系统中的应用。在本文中，我们报告了一种用于减少传感器漂移的通用封装技术。所描述的方法通过将传感器封装在填充有硅酮的医用级聚氨酯气囊中，将压力传感器与主要的漂移源（即与周围水环境的接触）隔离开来。使用商用微机械压阻式压力传感器进行的100天体外浸泡测试表明，其运行稳定，输出保持在参考压力传感器的1.8 cmH2O（1.3 mmHg）范围内。在类似的测试条件下，未隔离的传感器在参考值的10至20 cmH2O（7.4 - 14.7 mmHg）之间波动，从未稳定运行。在奥萨博猪身上的植入证明了该封装的稳健性及其在体内减少基线漂移的功效。
