The disk resonator gyroscope is an attractive candidate for high-performance MEMS gyroscopes. This gyroscope consists of a sensor and readout electronics, and the characteristics of the sensor directly determine the performance. For the sensor, a high-quality factor and long decaying time constant are the most important characteristics required to achieve high performance. We report a disk resonator gyroscope with a measured quality factor of 510 k and decaying time constant of 74.9 s, which is a record for MEMS silicon disk resonator gyroscopes, to the best of our knowledge. To improve the quality factor of the DRG, the quality factor improvement mechanism is first analyzed, and based on this mechanism two stiffness-mass decoupled methods, i.e., spoke length distribution optimization and lumped mass configuration design, are proposed and demonstrated. A disk resonator gyroscope prototype is fabricated based on these design strategies, and the sensor itself shows an angle random walk as low as 0.001°/√h, demonstrating true potential to achieve navigation-grade performance. The gyroscope with readout electronics shows an angle random walk of 0.01°/√h and a bias instability of 0.04°/h at room temperature without compensation, revealing that the performance of the gyroscope is severely limited by the readout electronics, which should be further improved. We expect that the quality factor improvement methods can be used in the design of other MEMS gyroscopes and that the newly designed DRG can be further improved to achieve navigation-grade performances for high-end industrial, transportation, aerospace, and automotive applications.

No abstract

No abstract

The serine protease PRSS8 has shown important physiological and pathological functions, but its roles in cancer initiation and progression are unclear. We developed and dynamically characterized a conditional knockout Prss8, p-Villin-Cre mouse model. We found that genetic deficiency of the Prss8 gene caused spontaneous colitis and an inflamed rectum at an early age and caused intestinal tumors at a late age, which were linked to increased intestinal cell proliferation and migration but decreased cell differentiation. Increased PRSS8 expression inhibited cancer cell growth and metastasis in nude mice and inhibited cancer cell migration, invasion, colony formation and tumor sphere formation in vitro, but decreased PRSS8 expression facilitated malignancies in vivo and in vitro. Gene profiling on manipulated cancer cells and intestinal epithelial cells of Prss8 mouse models, gene set enrichment analysis and mechanistic studies revealed that PRSS8 targeted the Wnt/β-catenin, epithelial-mesenchymal transition, and stem cell signaling pathways, which were further supported by the results from the TCGA data mining and validated by immunohistochemical staining on colorectal cancer tissue microarrays. In conclusion, PRSS8 is a novel tumor suppressor that plays critical roles in the suppression of colorectal carcinogenesis and metastasis.

In this paper, we present an SU-8 based evanescent waveguide with a vertical structure as a biomedical sensor. The waveguide is designed vertically to generate evanescent waves on both left and right surfaces for sensing. It is fabricated by E-beam lithography with only one-step process which has the advantage of a better surface quality compared with commonly used dry etching methods. Furthermore, fabrication time and cost is cut down greatly. The surface of the designed waveguide can be functionalized with antibodies to immobilize specific bacteria on it. After surface functionalization and incubation with E. coli solutions of different concentrations, the waveguides absorption was measured. The results demonstrate that the waveguide is sensitive to E. coli concentration changes. In addition, tapers were designed and added to the waveguide to relieve the alignment tolerance for the aim of making a plug-and-play bedside diagnostic system.