Project Title:
A High-Sensitivity, Real-Time, Non-Volatile Residue Monitor
13.03-6239
910747
A High-Sensitivity, Real-Time, Non-Volatile Residue Monitor
Femtometrics
1001 West 17th Street, Suite R
Costa Mesa
CA
92627
William D.
Bowers
714-722-6239
KSC
NAS10-11865
265
13.03-6239
910747
Abstract:
A High-Sensitivity, Real-Time, Nonvolatile Residue Monitor
The accepted method to measure non-volatile residue (NVR) on payload and orbiter
critical surfaces is the use of a one-square-foot witness plate to collect NVR over
a period of several weeks. The weight of the solvent-wash residue from the witness
plate is reported as NVR mass flux in units of mg/0.1 m2/month. This method is tedious
and time-consuming; it does not give a real-time measurement of NVR originating from
activities near the payloads and orbiter. An innovative approach is to measure NVR
in real time using a temperature-controlled surface acoustic wave (TCSAW) resonator.
The unparalleled stability and high mass sensitivity of the 200 MHz SAW resonator
enables NVR measurements down to 6 x 10-5 mg/0.1 m2 or 0.06 nanograms/cm2. The high
performance of the 200 MHz SAW resonator is realized by comparison to a 10 MHz temperature-controlled
quartz crystal microbalance that can measure NVR levels down to 1.3 x 10-2 mg/0.1
m2 or 13.3 nanograms/cm2. The 200 MHz TCSAW meets the 0.05 micrograms/cm2 detection
requirement for NVR.
A highly sensitive, real-time NVR monitor would be useful in government and industry
for monitoring surface contamination during the manufacturing, processing, and storage
of payloads, orbiter and space station components, and any other sensitive surfaces
in instrumentation and manufacturing processes.
SAW sensor, nonvolatile residue, real-time, piezoelectric crystal, microbalance