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    Item type:Publication, Access status: with files ,
    Design of a highly accurate low-cost thermistor-based sensor for the measurement of water surface temperatures in maritime research
    (AMA Service GmbH, 2024)
    Klar, Finn Jannek
    ;
    Torz, Niklas
    ;
    Kern, Thorsten Alexander
    In climate and oceanographic research, precise temperature measurements within the very limited temperature range of the ocean are essential. This paper covers the design and analysis of a temperature sensor that measures with millikelvin accuracy. The first prototype has an energy consumption of 84.64 mWs with a sampling time of 10 seconds per measurement and a component cost of less than 100 EUR. The proposed design is able to measure within 6 mK accuracy on a subset measurement range despite a simple three-point calibration. The core circuit is enhanced with two temperature sensing elements to allow for an increase in sensor sensitivity. A further approach on sensor readout is proposed and analyzed, showing good potential in combination with linearized temperature compensation for the major part of this sensors range.
    Publicationtype: Conference Poster
      96  67
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    On the Design of Low-Cost Inductive Conductivity Sensors for Salinity Measurement in Oceangoing IoT Applications
    (2022-05)
    Klar, Finn Jannek
    ;
    Harms, Julius
    ;
    Kern, Thorsten Alexander
    In this paper, a low-cost transformer type inductive conductivity sensor for the use of in situ measurement of seawater on oceangoing sensor buoys is designed, developed, and tested. The sensor design uses DAC and ADC peripherals of a SAME51 microcontroller. A single PCB holds the MCU, the coils of the transformer type sensor, and circuits for measurement and power supply. The sensor was tested in an ionic solution of increasing conductivity in the range of seawater. The processed readouts from the MCUs ADC sampling at 40 kHz are compared to those sampled by an external oscilloscope of 40 kHz sampling rate, connected to the ADCs inputs. The processed ADC data show a significantly higher sensor gain and sensor gain slope compared to the oscilloscope data. The influence of high-frequency noise in combination with the lower sampling rate is considered a possible cause. The measurement results show that a revision of the amplifier circuit, the target offset voltage, and the amplifier loop gain is necessary.
    Publicationtype: Conference Paper
      97
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    Item type:Publication, Access status: with files ,
    Development and implementation of a manufacturing concept for a low-cost inductive conductivity sensor for maritime applications
    (2021-12-09)
    Klar, Finn Jannek
    ;
    Kern, Thorsten Alexander
    In this work, a conductivity sensor based on a dual transformer is developed for use on self-sufficient buoys. The design and optimization of the physical sensor are based on simulation models in MATLAB. Based on the design of the double transformer and a given microcontroller, circuits for excitation and measurement amplification are designed. The circuits, microcontroller, and transformer are combined on a printed circuit board to form an embedded sensor. Based on the microcontroller and the cell constant required in conductivity measurement, software concepts are presented. The cell constant is determined through a series of experiments on the potted dual transformer.
    Publicationtype: Master Thesis
      205  1643