The Effect Of Crystalline Orientation On Vibration Sensitivity Of Silicon Micro-Resonators

In this work the effect of crystalline orientation on the acceleration sensitivity of Silicon-based MEMS oscillators is experimentally studied for the first time. The thin-film piezoelectric-on-Silicon (TPoS) platform is utilized to implement the oscillators as it enables resonators with low-motional resistance and high Q. A single lateral-extensional-mode resonator design is fabricated in \u3c100\u3e and \u3c110\u3e orientations on a \u3c100\u3e Silicon wafer. The resonators are then used to assemble two oscillators operating at ~25MHz and ~27MHz respectively. The average acceleration sensitivity of the oscillator containing the \u3c110\u3e resonator is measured to be ~4×10-10 at vibration frequencies up to 2700 Hz; an astonishing two orders of magnitude lower than that of the oscillator utilizing the \u3c100\u3e resonator. The acceleration sensitivity in these Silicon-based resonators is believed to stem from nonlinear elastic properties of Silicon, which is dependent on crystalline orientation as well as doping type/concentration. The Silicon substrate used in this work is Phosphorous-doped at ~5e19 cm-3 concentration

Tackling challenges in care of Alzheimer's disease and other dementias amid the COVID-19 pandemic, now and in the future.

We have provided an overview on the profound impact of COVID-19 upon older people with Alzheimer's disease and other dementias and the challenges encountered in our management of dementia in different health-care settings, including hospital, out-patient, care homes, and the community during the COVID-19 pandemic. We have also proposed a conceptual framework and practical suggestions for health-care providers in tackling these challenges, which can also apply to the care of older people in general, with or without other neurological diseases, such as stroke or parkinsonism. We believe this review will provide strategic directions and set standards for health-care leaders in dementia, including governmental bodies around the world in coordinating emergency response plans for protecting and caring for older people with dementia amid the COIVD-19 outbreak, which is likely to continue at varying severity in different regions around the world in the medium term