Abstract: A microelectromechanical apparatus includes a base and a thin film including a stationary part disposed on the base, a peripheral part, a central part surrounded by the peripheral part, and a first and second elastic part. The first elastic part is connected to the stationary part and the peripheral part. The second elastic part is connected to the peripheral part and the central part. When low frequency signal is input to a first electrode of the first elastic part, the peripheral part and the and the central part respectively vibrate with a first and second low-frequency amplitudes. When high-frequency signal is input to a second electrode of the second elastic part, the peripheral part and the central part respectively vibrate with a first and second high-frequency amplitudes. A difference between the first and second low-frequency amplitudes is smaller than a difference between the first and second high-frequency amplitudes.

Abstract: A meat roasting device having an automatically rotated barbecue grill mainly comprising: a furnace frame, a barbecue grill, and a driving device, wherein said driving device is fixed on the support plate of the furnace frame, and is engageable with a barbecue grill having an elastic clamping force by a driving bushing. When the driving device rotates, the barbecue grill may be driven to rotate by the driving bushing in the furnace frame.