Chang Wen-Ying, Chen Chi-Chun, Chang Chih-Cheng, Yang Chin-Lung
Department of Electrical Engineering, National Cheng-Kung University, Tainan 701, Taiwan.
Department of Pulmonary Medicine, Taipei Medical University Shuang-Ho Hospital, Taipei 235, Taiwan.
Sensors (Basel). 2014 Apr 17;14(4):6922-37. doi: 10.3390/s140406922.
This paper presents a cost-effective sensor system for mattresses that can classify the sleeping posture of an individual and prevent pressure ulcers. This system applies projected capacitive sensing to the field of health care. The charge time (CT) method was used to sensitively and accurately measure the capacitance of the projected electrodes. The required characteristics of the projected capacitor were identified to develop large-area applications for sensory mattresses. The area of the electrodes, the use of shielding, and the increased length of the transmission line were calibrated to more accurately measure the capacitance of the electrodes in large-size applications. To offer the users comfort in the prone position, a flexible substrate was selected and covered with 16 × 20 electrodes. Compared with the static charge sensitive bed (SCSB), our proposed system-flexible projected capacitive-sensing mattress (FPCSM) comes with more electrodes to increase the resolution of posture identification. As for the body pressure system (BPS), the FPCSM has advantages such as lower cost, higher aging-resistance capability, and the ability to sense the capacitance of the covered regions without physical contact. The proposed guard ring design effectively absorbs the noise and interrupts leakage paths. The projected capacitive electrode is suitable for proximity-sensing applications and succeeds at quickly recognizing the sleeping pattern of the user.
本文提出了一种经济高效的床垫传感器系统，该系统能够对个人的睡眠姿势进行分类并预防压疮。该系统将投射电容传感应用于医疗保健领域。采用充电时间（CT）方法灵敏且准确地测量投射电极的电容。确定了投射电容器所需的特性，以开发用于传感床垫的大面积应用。对电极面积、屏蔽的使用以及传输线长度的增加进行了校准，以便在大型应用中更准确地测量电极电容。为了让使用者在俯卧姿势时感到舒适，选择了柔性基板并覆盖16×20个电极。与静态电荷敏感床（SCSB）相比，我们提出的系统——柔性投射电容传感床垫（FPCSM）配备了更多电极，以提高姿势识别的分辨率。至于身体压力系统（BPS），FPCSM具有成本更低、抗老化能力更强以及能够在不进行物理接触的情况下感测覆盖区域电容的优点。所提出的保护环设计有效地吸收了噪声并中断了泄漏路径。投射电容电极适用于接近感应应用，并成功地快速识别用户的睡眠模式。
