ISR research accomplishments
DRIE Microfabrication Technology for Navy Safety and Arming Systems
Accomplishment
To demonstrate the respective
components of a Naval Safety and Arming (S&A) device in Deep
Reactive Ion Etching (DRIE) on a Silicon on Insulator (SOI) substrate: actuators, G-Sensors, Explosive Train Barriers, Hydrostats (Pressure activated
lock), Optical Reflectors, Device Z-Axis Delimiters. DRIE G-Sensor demonstrated. 100um-thick silicon as an explosive
barrier demonstrated.
Initial DRIE G-Sensor Tests
G-Sensors. Threshold G-Sensors are used
in safety and arming systems to detect weapon launch. A latched
G-Sensor is an acceptable indication of that the weapon has seen
a specific acceleration environment.
Test G-Sensor shown latched at a 221g/1.86 ms pulse. Did not latch at a previous pulse of 211 g/ 4.99ms. An identical G-Sensor yielded the same result.
Implications. This test, while preliminary, is significant because it indicates the functionality and repeatability of this G-sensor design in DRIE. Future designs of other components use aspects of the G-Sensor--explosive barrier is a similar spring suspended structure. Success of the G-Sensor indicates DRIE barriers will also translate similar displacements.Si Barrier Test
Slapper detonators. A Slapper is
a small “fuse” that pops when a high voltage (~1kV)
is discharged across it. This fuse accelerates a kinetic flyer
into an HNS4 explosive pellet. If the path between the pellet
and slapper is properly interrupted then the arming device is
in a SAFE condition. LIGA Ni has been proven as an effective
MEMS interrupter between slappers and HNS4 pellets.
Si as an explosive barrier. Preliminary tests were performed to determine the effectiveness of Si barriers as interrupters. 25, 50 and 100 um dies were placed in the fire train as shown.
Results. 25, 50 and 100 um prevented detonation of the pellet. 25 and 50 um were locally shattered thru at the slapper. 100um protection was better but marginally effective Additional material will have to be added to thinner 25 and 50 barriers. 100um TBD.
Beginning in 1995,
the Naval Surface Warfare Center started developing a MEMS S&A device
for torpedoes. This ongoing effort embraces the relatively costly LIGA
process. Since 1995, SOI-DRIE technology has greatly matured. This technology
offers several potential advantages over LIGA. Reliability issues, optical
performance, electro-mechanical performance, and cost issues may direct
the Navy to DRIE based S&As.
Research team
D. DeVoe (ME/ISR), G. Smith (UMd and Naval Surface Warfare Center), L. Fan (Naval Surface Warfare Center)
For more information
L. Fan, H.Last, R. Wood, et al., “SLIGA Based underwater weapon safety and arming system, ”Microsystem Technologies 4 (1998), 168-171.
