This paper presents a novel single proof-mass tri-axis capacitive type complementary metal oxide semiconductormicroelectromechanical system accelerometer to reduce the footprint of the chip. A serpentine out-of-plane (Z-axis) spring is designed to reduce cross-axis sensitivity. The tri-axis accelerometer has been successfully implemented using the TSMC 2P4M process and in-house postprocessing. The die size of this accelerometer chip containing the MEMS structure and sensing circuits is 1.78 × 1.38 mm, a reduction of nearly 50% in chip size. Within the measurement range of 0.8 ∼ 6G, the tri-axis accelerometer sensitivities (nonlinearity) of each direction are 0.53 mV/G (2.64%) for the X-axis, 0.28 mV/G (3.15%) for the Y-axis, and 0.2 mV/G (3.36%) for the Z-axis, respectively. In addition, the cross-axis sensitivities of these three axes range from 1% to 8.3% for the same measurement range. The noise floors in each direction are 120 mG/rtHz for the X-axis, 271 mG/rtHz for the Y-axis, and 357 mG/rtHz for the Z-axis. Index Terms-Complementary metal oxide semiconductor (CMOS)-MEMS, tri-axis accelerometer. I. INTRODUCTIONS MALL SIZE, low cost, multifunction, low power consumption, and easy integration with consumer electronics are some of the primary design issues for commercial microelectromechanical system (MEMS) applications such as inertia sensors and microphones. Various approaches have been reported to meet the related design requirements. The fabrication of micromechanical components using existing IC foundries provides a promising option to realize MEMS sensors. MEMS sensors can be fabricated by means of a complementary metal oxide semiconductor (CMOS) process together with post-CMOS processing, named the CMOS-MEMS process [1].

No abstract

No abstract

This study reports a novel approach to the implementation of 3D carbon nanotube (CNT) interdigitated finger electrodes on flexible polymer, and the detection of strain, bending curvature, tactile force and proximity distance are demonstrated. The merits of the presented CNT-based flexible sensor are as follows: (1) the silicon substrate is patterned to enable the formation of 3D vertically aligned CNTs on the substrate surface; (2) polymer molding on the silicon substrate with 3D CNTs is further employed to transfer the 3D CNTs to the flexible polymer substrate; (3) the CNT-polymer composite (~70 μm in height) is employed to form interdigitated finger electrodes to increase the sensing area and initial capacitance; (4) other structures such as electrical routings, resistors and mechanical supporters are also available using the CNT-polymer composite. The preliminary fabrication results demonstrate a flexible capacitive sensor with 50 μm high CNT interdigitated electrodes on a poly-dimethylsiloxane substrate. The tests show that the typical capacitance change is several dozens of fF and the gauge factor is in the range of 3.44-4.88 for strain and bending curvature measurement; the sensitivity of the tactile sensor is 1.11% N(-1); a proximity distance near 2 mm away from the sensor can be detected.

No abstract