The precise temperature control of ball SAW sensors for trace moisture measurement at ppb level of concentration

Yusuke Tsukahara, Ball Wave (JP)

In the production of semiconductor devices and lithium-ion batteries, the management of trace moisture in pure gases is important. We have developed a trace moisture measurement equipment, Falcon Trace, in which we measured the change in the phase velocity of surface acoustic waves (SAW) propagating along the amorphous silica layer on a spherical single crystal quartz exposed to the gas flow containing a very small amount of moisture. The sensor consisting of a spherical single crystal is called a ball SAW sensor. The sensitivity of the ball SAW sensor depends on the temperature, hence the estimated gas concentration could be affected when the temperature varies too much. This problem was solved by a method of simultaneously measuring the temperature and trace moisture concentration using the ball SAW sensor operated at two different frequencies Thus, it would be possible to measure the trace moisture at ppb level of concentration, even in the gas flow with a varying temperature.


Pen Profile

• Co-founder and board member of Ball Wave Inc. which was launched in November 2015 in Sendai, Japan. Visiting professor at School of Advanced Science and Engineering, Waseda University, from 2017.
• Co-founder and CEO of Riken Genesis in Tokyo from 2007 to 2016 launching the clinical genomics services.
• Head of Corporate R&D Strategy of Toppan Printing Co., Ltd. from 2001 to 2007.
• Board member of E Ink corp. in Cambridge, USA, from 2002 to 2005, establishing the R&D of Electronic Paper and its commercialization.
• Co-Director at Oxford Toppan Centre for Nanomaterials from 1996 to 2006.
• An Industrial Fellow of Wolfson College of Oxford University from 1998 to 2003.
• A Summit Fellow at Industrial Materials Institute, National Research Council Canada from 1991 to 1992.
• B. S. degree in Physics from Waseda University.
• Ph. D. degree in Electrical Engineering from Tohoku University.

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