Aerospace and Electronic Systems Magazine September 2017 - 35

holds the microcontroller device, the rf interface module, as well as
an insulation displacement connector (IDC) for the attachment of
the sensor board. The two pairs of sensor boards employed by the
system are as follows: a) steval-mkI165v1 by STMicroelectronics
holding lps25hb sensor; b) 2652 Adafruit by the latter corporation
holding bme280 sensor.
In order to explore deviation in each pair of sensors' output
when acquiring the same pressure value (under the same temperature and humidity conditions), endpoint devices are placed
inside an airtight enclosure with pump for the air abstraction (Figure 1(a)). This particular feature renders feasible the generation
of vacuum, while applying a gentle mechanical force to the enclosure's relief valve causes small increments of the inside pressure (where minimum rise is found to be of 1-2 mbar, in practice).
Successive repetitions of the latter action allow the observation of
sensors' deviation in several pressure levels and up to the current
pressure of ambient air. Because of the wireless feature of the testbed prototype, the experiment can be conducted not only in room
temperature, but also in the interior of an oven (Figure 1(b)) or
fridge (Figure 1(c)); thereby augmenting experimental observation
at different temperature levels.
The conventional and more accurate experiments are feasible
through an exceptionally expensive apparatus, that is, a pressure
controller (connected to a regulated source of dry nitrogen) for
maintaining high-precision pressure in a closed volume. This
setup supports an accurate evaluation of sensors' deviation below (with the additional employment of a vacuum pump) and
above the current atmospheric pressure. For instance, it is possible to estimate repeatability error (i.e., the inability of sensor
to repeat same values under identical conditions), hysteresis error (i.e., the deviation in sensor's output at a specified pressure
when this value is approached from opposite directions), etc. The
additional employment of an environmental chamber for temperature control extends experimentation at different temperature
levels, as well. While these observations cannot be achieved by
the proposed testbed, it is however possible to predict and experimentally evaluate performance of MEMS pressure sensors in
differential altimetry systems.

output signal). Each individual measurement consisted of 30
pressure samples, while the average pressure difference for each
pair of sensors was determined in Matlab. Room, fridge, and
oven temperature levels were found to be of T≅30°C, T≅10°C,
and T≅50°C, respectively. This information derived from the
temperature sensing element also embedded in the barometric
sensors.
The data acquisition process (obtained inside the fridge)
through the LabVIEW user interface, is given in Figure 2. The gentle mechanical force to the enclosure's relief valve causes small increments of the pressure level. The latest measurement step depicts

PERFORMANCE ANALYSIS OF MEMS PRESSURE SENSORS
Three measurement sets at room, fridge, and oven temperatures
were obtained for 8 different pressure levels, with the range being of approximately 0.91-0.98 bar (as identified by the sensors'
SEPTEMBER 2017

Figure 1.

Testbed prototype and measurements procedure.

IEEE A&E SYSTEMS MAGAZINE

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine September 2017