Microelectromechanical systems (MEMS)-based capacitive pressure sensors are typically fabricated using siliconmicromachining techniques. In this paper, a novel liquid-crystal polymer (LCP)-based MEMS-capacitive pressure sensor, fabricated using printed-circuit-processing technique, is reported. The pressure sensor consists of a cylindrical cavity formed by a sandwich of an LCP substrate, an LCP spacer layer with circular holes, and an LCP top layer. The bottom electrode and the top electrode of the capacitive pressure sensor are defined on the top side of the LCP substrate and the bottom side of the top-LCP layer, respectively. An example pressure sensor with a diaphragm radius of 1.6 mm provides a total capacitance change of 0.277 pF for an applied pressure in the range of 0-100 kPa. Index Terms-Capacitive sensors, liquid-crystal polymer (LCP), microelectromechanical systems (MEMS), pressure sensors, printed-circuit board (PCB) MEMS.

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The reliability of electrostatically actuated ohmic contact type MEMS relays has been investigated. Multi-contact MEMS relays laterally actuated using electrostatic comb-drive actuators were used in this study. The MEMS relays were fabricated using the MetalMUMPs process, which uses a 20 µm thick electroplated nickel as the structural layer. A 3 µm thick gold layer was electroplated on the electrical contact surfaces. An example MEMS relay with planar contacts of area 80 µm × 20 µm and spacing of 10 µm between the movable and fixed contacting surfaces is discussed. The overall size of the relay is approximately 3 mm × 3 mm. ‘Resistance versus applied voltage’ characteristics have been studied. At an applied dc bias voltage of 120 V, the movable fingers make initial contact with the fixed fingers. The ‘resistance versus applied voltage’ characteristics have been measured for an applied bias voltage in the range of 172–220 V. Reliability testing of the MEMS relay up to one million actuations has been carried out and the resistance degradation with actuation cycles is discussed.

This paper provides a theoretical basis for eliminating or reducing the energy consumption due to transients in a synchronous digital circuit. The transient energy is minimized when every gate has no more than one output transition per clock cycle. This condition is achieved for a gate when the gate delay equals or exceeds the maximum di erence between path delays at gate inputs. In practice, path delays are adjusted either by increasing gate delays or by inserting delay bu ers. The minimum transient energy design is obtained when no delay bu er is added. This design requires possible increases in gate delays to meet the minimum energy condition at all gates. However, the delay of the critical path may be increased. In an alternative design, where the critical path delay is not allowed to increase, delay bu ers may have to be added. The theory in this paper allows trade-o s between minimum transient energy and critical path delay. We formulate the problem as a linear program to obtain the minimum transient energy design with the smallest number of delay bu ers for a given overall delay of the circuit. An optimized four-bit ALU circuit is found to consume 53 peak and 73 average power compared t o the original circuit.