General Objective: To develop a pressure sensor module (BMP180) to be tailored for flood

monitoring integration.

Specific Objectives:

To operate the BMP180 pressure sensor module to Arduino Nano and to verify the factory calibration by
comparing to a standardized barometer.

To compare the barometric reading from the sensors in an exposed setup versus an enclosed setup.

RRL

Background and Context

Piezoresistive pressure transducers use a combination of silicon, as the construction material

for the mechanical stress amplifiers (membranes, cantilever beams and bridges), and
piezoresistive strain gauges. The mechanical stress amplifiers are used to transform the
pressure into stress and the particular mechanical design is chosen to provide both the required
sensitivity and resolution for a given application. Pressure transducers are usually formed from
a membrane that is hermetically sealed to a support and also separates the reference pressure
from the pressure to be measured. Silicon-to-Pyrex anodic bonding techniques (Wallis &
Pomerantz, 1969; Cozma & Puers, 1995) are often used for absolute pressure sensors.
Pressure transducer drift may arise when either the active
elements or electrical connections are constructed from materials with different thermal
expansion coefficients. This is the case with silicon and Pyrex and designs, shown in Figure XX,
have been used to minimize these effects. Silicon piezoresistive strain gauges are machined
into supporting membranes with a standard integrated circuit (IC) process. Silicon-based MEMS
can provide pressure transducers with μm dimensions, which can withstand pressures up to 100
MPa. Mono-crystalline silicon, owing to the stability of the crystal, reduces the observed
hysteresis. In Figure XX a schematic of a typical pressure sensor is shown.
Figure XX. Schematic cross-section through a pressure gauge formed from an Si membrane
and strain gauge doped into specific locations to detect the mechanical deformation arising from
the application of a pressure difference. This Si element is sealed to the support with Pyrex, that
is in turn mounted on a base to provide support for the electrical connections. Extracted from
Suski, et al. (2003)

Spencer et al. (1988) and Chau and Wise (1987) have evaluated the performance of both
piezoresistive and capacitive pressure transducers. The theoretical performances of miniature
capacitive and piezoresistive pressure transducers have been described (Chau and Wise, 1987)
and a review article on micromachined pressure sensors presented by Eaton and Smith (1997).

Spencer et al. (1988) introduced the concept of a minimum detectable signal, β, for evaluating
pressure transducers. The β value represents the theoretical detection limit, defined as the
noise expressed as an equivalent pressure fluctuation, indicating the uncertainty from the
transduction process and the transducer's resolution. This definition assumes the cancellation of
all systematic errors and does not consider long-term drift.

There are three types of noise in electrical circuits: Schottky effect (shot noise), Johnson
(thermal) noise, and 1/f noise. Schottky noise arises from electric potential barriers at p-n
junctions, while Johnson noise is due to energy dissipation processes, and both have flat
spectral densities up to GHz frequencies. 1/f noise results from trapping centers near the device
surface. The change in the resistor bridge output voltage Δ V arising from a pressure change Δ p
is given by:

Δ V =α R V B Δ p

where α R is the pressure sensitivity of the transducer and V Bthe applied voltage. The β is
obtained by equating Δ V with the r.m.s. Johnson noise to give
1
1
β= ( 4 kTR Δ f ) 2
αR V B

where Δ f is the frequency bandwidth, R the resistance, k Boltzmanns' constant, and T

temperature. For capacitive pressure sensors the noise, therefore β cannot be generalized and
must be defined for that particular detection circuit.

According to Suski, et al. (2003), five primary types of pressure transducers are recommended for
high-accuracy gas pressure measurements ranging from 0.1 to 1000 Pa. These transducers
respond to the force exerted by an applied pressure difference, and as long as there are no
chemical reactions between the gas and the materials used in the construction of the transducer,
the readings remain consistent regardless of the gas used.

Temperature variations can influence the performance of all these transducers. Consequently,
capacitive diaphragm gauges and quartz Bourdon gauges are typically operated with their
temperature regulated to around 318 K (45 °C). Quartz resonance gauges feature an internal
quartz-crystal temperature sensor for thermal compensation. Both MEMS resonant Si gauges and
MEMS piezoresistive Si gauges are temperature compensated. Capacitive diaphragm gauges,
quartz Bourdon gauges, and quartz resonance gauges are precision instruments that perform
optimally when protected from mechanical or thermal shock and over-pressure.

Bande & Shete (2017) developed an IoT-based flood monitoring system employing an artificial
neural network where temperature, pressure, humidity, rainfall and water level data were collected
for temporal analysis for flood prediction. The IoT approach is used for data collection from
sensors and ANN is used for data prediction.

BMP180

The BMP180 sensor is a versatile MEMS-based device capable of measuring temperature,

pressure, and altitude (Subair & Abraham, 2014; Gaikwad et al., 2023). It has been utilized in
various applications, including weather monitoring stations and high-altitude balloon
experiments (Gaikwad et al., 2023; Youn, 2020). The sensor communicates using the I2C
protocol and can be integrated with microcontrollers like Arduino or Raspberry Pi for data
collection and processing (Gaikwad et al., 2023; Abburu et al., 2020). In weather monitoring
applications, the BMP180 enables real-time tracking of environmental parameters, which can be
stored in databases and displayed through graphical user interfaces (Gaikwad et al., 2023). For
high-altitude balloon experiments, the sensor can trigger cut-down mechanisms based on
specific altitude, temperature, or pressure conditions (Youn, 2020). Additionally, the BMP180
has been incorporated into healthcare monitoring systems, working alongside other sensors to
measure vital signs and transmit data to mobile applications (Abburu et al., 2020).

The BMP280 and similar sensors (BMP085, BMP180) are widely used for measuring air
pressure and altitude. These sensors offer high accuracy, precision, and low power
consumption (Wang Cheng, 2011; M. Vasylenko & V. Dzhus, 2022). Studies have shown that
the BMP280 sensor's performance can be improved through statistical analysis and calibration
techniques. One-way ANOVA and Tukey tests can identify differences between sensors, while
linear regression can enhance accuracy (H. Kusuma et al., 2023). When compared to standard
meteorological instruments, BMP280-based devices demonstrate high accuracy and precision,
with a calibration equation yielding a coefficient of determination (R) of 0.99998 (Miftahul Khaery
et al., 2020). These sensors can be integrated with microcontrollers like Arduino Uno or
C8051F310 to create portable altitude measurement systems with features such as temperature
compensation, noise processing, and OLED display (Wang Cheng, 2011; Miftahul Khaery et al.,
2020; M. Vasylenko & V. Dzhus, 2022).

MPL3115A2

The MPL3115A2 is a commercially available MEMS pressure sensor that has been studied for
its performance under extreme conditions. Lall et al. (2018) investigated the effects of high-
temperature operating life (HTOL) at 125°C and low-temperature storage (LTS) at -35°C on this
sensor. Their research aimed to quantify damage progression and identify potential failure sites
in harsh environments. The study focused on measuring incremental shifts in parameters such
as absolute pressure and offset. While not specifically mentioning the MPL3115A2, Linke (2003)
provides an overview of 1-Wire technology and its applications in environmental sensing,
including barometric pressure measurement. This technology enables the construction of
sensors that can measure various parameters on a single twisted-pair cable. Although the
MPL3115A2 is not explicitly mentioned in Linke's paper, it demonstrates the broader context of
pressure sensing technologies and their applications in environmental monitoring.

Table 2.3. Pressure Sensors used in Related Studies

Sensor Low Cost Commercially Resolution Accuracy (Pressure

Used (Pressure) )
MPL3115A2 No Yes 1.5 Pa typical ± 0.4 kPa typical
BMP180 Yes Yes 0.01 hPa typical ±0.12 hPa typical

(Research questions)

Among the studies presented, each neglected to address the inaccuracy of sensors related to their
physical integration into respective systems. The physical aspects, such as mounting position,
environmental exposure, and interaction with other system components, can significantly impact
sensor performance. Without considering these factors, the reliability and accuracy of the sensor
data could be compromised. This paper includes the physical observation of pressure readings in
an exposed vs. enclosed device setup of the pressure sensor.

METHODOLOGY

Specific Objectives Methodology

1) Specific Objective 1 A. Title of Methodology for Step 1.
“Title of Methodology for Step 1”
should be provided with a title.
(Example: Integration of Sensors
and Microcontroller) This could be
hardware design/software design,
gathering of data or mathematical
computations depending on the
objective.
B. Title of Methodology for Step 2.
“Title of Methodology for Step 2”
should be provided with a title.
(Example: Machine learning
Algorithm) This could be hardware
design/software design, gathering of
data or mathematical computations
depending on the objective.

2) Specific Objective 2 C. Title of Methodology for Step 3.

“Title of Methodology for Step 3”
should be provided with a title. This
could be hardware design/software
design, gathering of data or
mathematical computations
depending on the objective

3) Specific Objective 3 D. Title of Methodology for Step 4.

“Title of Methodology for Step 4”
should be provided with a title. This
could be hardware design/software
design, gathering of data or
mathematical computations
depending on the objective