Unique microelectromechanical systems switch simulator uncovers material property mysteries and opportunities.

AFRL materials scientists developed a highly sophisticated laboratory instrument that simulates the effects of physical forces and electrical current on microelectromechanical systems (MEMS) switches. The simulator’s performance has induced revolutionary insights into microscale switches—how they work and what causes them to fail.

MEMS switches offer substantial performance enhancement over current electromechanical (EM) and solid-state (SS) switches. They demonstrate significant potential for military and commercial use, especially for radio frequency (RF) applications. Realizing this potential, however, requires a greater understanding of both the contact physics involved with electrode materials and the material characterization properties at the nanoscale level.

The advantages of MEMS RF switches over conventional EM and SS switches include (1) higher linearity, (2) lower insertion loss, (3) lower power consumption, (4) reduced size, (5) higher shock resistance, (6) wider temperature range, (7) improved isolation, and (8) lower cost. The improved performance and reliability that MEMS RF switches (see figure) provide will benefit existing systems and create a new paradigm for future system development. Immediate applications include radar, aviation instrumentation, and cellular phones.

Among the switch devices currently used in RF systems, EM relays offer the best high-frequency performance in terms of low insertion loss, high isolation, and good power handling (up to several watts). Unfortunately, EM devices are large, slow, and expensive, and they lack durability. Conversely, SS switches offer chip-level integration, small size, fast switching times, excellent durability, and low cost. However, they generally do not perform well in broadband applications; they have high insertion loss and poor isolation; and their high losses tend to nullify their size benefits due to the need for signal amplifiers, which increase power consumption and complexity. In choosing between EM and SS switching, designers are accustomed to accepting the necessary trade-off between the high-frequency performance offered by EM and the durability, size, low cost, and switching speed of SS. Therefore, the appeal of MEMS RF switches is that they offer the performance of EM switches with the durability, size, and low cost of SS devices.