Instrumentation & Measurement Magazine 25-8 - 10

TC-09 Subcommittee:
Capacitive Sensors
Markus Neumayer, Thomas Bretterklieber and Hannes Wegleiter
C
apacitive sensing is a versatile sensor technology
and has proven itself in many different measurement
and detection tasks [1]. The measurement
principle is based on the capacitive coupling between objects
(electrodes) [2]. The coupling can be influenced by objects
and/or the geometry between the objects, making capacitive
technology suitable for a wide range of measurement applications
in science and technology. Sensing examples are given
by proximity, pressure, position and displacement, force, humidity
[3], fluid level, environmental sensing [4], [5], safety
applications [4], [6], [7], process measurements including
tomographic sensing [8], [9], etc. In Fig. 1, the principle of a capacitive
sensing system is shown [1], [10]. A capacitive sensor
is designed for the specific measurand x. After the capacitance
value has been acquired by a measurement circuit, the measurement
result xˆ is evaluated. This involves signal models
and models for the elements of the measurement systems as
well as calibration measurements.
Following Fig. 1, the successful development and application
of capacitive sensing technology requires knowledge
from several fields such as physical sensor modeling, circuitry
design and electronic systems, signal processing and
measurement in general [10]. Due to its relevance and broad
aspects, the Technical Committee on Sensor Technology
(TC-09-Sensor Technology) of the IEEE Instrumentation
and Measurement Society has established the TC-09 Subcommittee:
Capacitive Sensors (TC-09 SCS). The TC-09 SCS
bundles research activities in the field of capacitive sensing
technology and its application in industrial environments
to:
◗ Develop, promote and support capacitive sensor-related
technologies.
◗ Develop new methods to meet industry's need for cost
efficient, robust, reliable and accurate sensors.
◗ Review capacitive sensors and their applications in the
user community, government and industry.
◗ Provide a platform for workshops and symposia to better
connect different experts in the field.
◗ Maintain liaison with other societies and organizations
working in the same or related areas.
This article provides an overview of TC-09 SCS activities.
In order to demonstrate the potential of capacitive measurement
technology, we start with two challenging application
examples from members of the TC-09 SCS to demonstrate
frontiers and research in capacitive sensing. The applications
are in the fields of environmental sensing technology and process
measurement technology [9], [11]. Following, we address
future research directions and present the promotion of capacitive
sensing technology in industry and academics by the
TC-09 SCS.
Fig. 1. Scheme of a capacitive sensing system, based on [10]. The measuring
capacity is influenced by the measurand x. From the measurement of the
capacitance the measurement result xˆ is formed.
10
Environmental Sensing and Process
Tomography with Capacitive
Technology
In this section, we present two measurement tasks highlighting
the capabilities of capacitive sensing. Both
examples show measurement problems in harsh environments.
We address the measurement problem, required
research steps for the application of capacitive sensing and
conclude with demonstration examples showing actual
field experiments.
IEEE Instrumentation & Measurement Magazine
1094-6969/22/$25.00©2022IEEE
November 2022
Instrumentation & Measurement Magazine 25-8

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