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Flow Cell With Flat Electroded Transducers

IP.com Disclosure Number: IPCOM000101035D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Borges, G: AUTHOR [+3]

Abstract

This article describes a design for a flow cell in which the electroded face of a crystal transducer forms part of its wall. The requirements for low mounting stress and positive liquid sealing on the crystal conflict with the need for low cell volume and small unswept volume. These conflicts are resolved by the design described.

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Flow Cell With Flat Electroded Transducers

       This article describes a design for a flow cell in which
the electroded face of a crystal transducer forms part of its wall.
The requirements for low mounting stress and positive liquid sealing
on the crystal conflict with the need for low cell volume and small
unswept volume.  These conflicts are resolved by the design
described.

      The design is illustrated in the figure.  This figure is
illustrative only and is not to scale.  The unique feature is that
the sealing elastomer, a sheet of silicone rubber, serves not only as
a seal for the cell but also acts as the cell body.  The use of
the flat elastomer provides a large area for sealing, and a positive
seal is achieved with only a small applied stress.  This contrasts
sharply with the use of "O"-rings in the usual implementation where a
large stress must be applied to obtain a positive seal because of the
limited sealing area.  This low stress is important not only to
minimize damage to the mounted transducer, but also to prevent
erratic behavior of transducers which are stress-sensitive.  In other
words, the frequency stability and losses of quartz resonators are
extremely sensitive to stress.

      Using the elastomer as the cell body also provides for a
relatively small cell volume and a small volume where liquid can be
trapped and stagnate.  This again contrasts with the the use of a
solid plastic for the cell body, with the elastomer (or "O"-...