Abstract: A membrane hetero-structure includes a polymer layer and a single-layer or multi-layer graphene sheet disposed on the polymer layer. The membrane hetero-structure is tensioned across a frame having an opening such that both the polymer layer and the graphene sheet extend across the opening. An optional rigid member is provided in a center of the membrane to be spaced apart from edges of the opening. The assembly of the frame and membrane hetero-structure forms an electrostatically driven micro-electro-mechanical system (MEMS) or sound generation and recording apparatus. In one instance, when a voltage signal is applied between an electrode layer parallel to the membrane and contacts on the frame that are electrically connected to the graphene sheet, the membrane hetero-structure is actuated.

Abstract: A membrane hetero-structure includes a polymer layer and a single-layer or multi-layer graphene sheet disposed on the polymer layer. The membrane hetero-structure is tensioned across a frame having an opening such that both the polymer layer and the graphene sheet extend across the opening. An optional rigid member is provided in a center of the membrane to be spaced apart from edges of the opening. The assembly of the frame and membrane hetero-structure forms an electrostatically driven micro-electro-mechanical system (MEMS) or sound generation and recording apparatus. In one instance, when a voltage signal is applied between an electrode layer parallel to the membrane and contacts on the frame that are electrically connected to the graphene sheet, the membrane hetero-structure is actuated.

Abstract: A wireless transmitting/receiving circulator circuit is disclosed. The circuit comprises a first band-pass filter, a filter and a second band-pass filter. The first band-pass filter is coupled to the receiving end of a wireless device and an antenna for receiving signals from the antenna and filtering the signals to produce a receiving signal. The receiving signal is transmitted to the receiving end of the wireless device. The filter is coupled to the antenna for blocking antenna signals containing the transmitting wave band. The second band-pass filter is coupled to the transmitting end of the wireless device and the filter for receiving signals from the transmitting end and filtering the signals to produce a transmitting signal. The transmitting signal is transmitted via the antenna after passing through the filter.