Application of dielectric spectroscopy for determination of biomaterials properties


Application of dielectric spectroscopy for determination of biomaterials properties

Leader: Prof. DSc Wojciech SKIERUCHA
Team: PhD Andrzej Wilczek; PhD Agnieszka Szypłowska; PhD Marcin Kafarski; PhD Justyna Szerement


The research will concentrate on the following areas:


a)    quality testing of stone fruit on the base of their electrical properties, particularly in broadband frequency range 20 Hz – 20 GHz using measurement techniques of dielectric spectroscopy,
Analysis of stone fruit dielectric response, which began in 2015 when apples (Jonagold variety Dekosta) during the climacteric period were measured, will be continued. The aim of the research is to determine dielectric indicators of ripeness during storage and dielectric indicators of the optimum harvesting time. Specially designed and manufactured dielectric probes as well as a measure stand  (Fig. 1) will be used in the research, and the dielectric parameters of fruit, such as: electrical conductivity at low frequencies, the frequency values corresponding to the dielectric dispersion caused by the interphase Maxwell-Wagner effect, bound water and water free, real and imaginary parts of the measured complex dielectric permittivity at ISM (industrial-scientific-medical) frequencies, loss tangent, will be correlated with physicochemical quality parameters of the studied fruit, i.e. firmness, starch content, soluble solids content. It is planned to investigate several varieties of apples and pears in the period immediately before and after harvesting and during the initial period of storage.


b)    conducting research and development on new hardware and software measurement systems for  monitoring soil moisture, salinity and temperature.
Continuous development, miniaturization, increasing functionality and reliability, universality and accessibility of electronic and information tools create opportunities for their application in monitoring systems for physical and chemical parameters of the soil environment. Based on previously developed and commercialized by the IA PAS TDR soil moisture measurement systems, we work on the development of a soil profile probe for soil moisture, temperature and salinity (Fig. 2). The probe will implement the invention of high frequency pulse conversion method that is the subject of the national patent (P.414096 dated. 09.21.2015 r.). The probe will not only enable the measurement of the three physical quantities at certain depths of the soil, but also their temporal dynamics. The profile probe will implement the latest developments in the field of Internet of Things (IoT – the internet of things), i.e. wireless connection of multiple profile probes in the monitoring system and its control through a WEB server, economical battery power supply, communication with the probes via a mobile application. Digital FEM simulation technique will be applied during the development of the profile probe, i.e. reflective and transmission parameters of electromagnetic pulses in radio and microwave frequencies (10 MHz – 20 GHz) propagating along transmission lines on the surface of the profile probe will be analyzed. The use of FEM digital simulation for sensors of various mechanical design, significantly simplifies the analysis of the electromagnetic field in the material being measured in a volume sensor. In contrast to the digital simulation, obtaining analytical description of electromagnetic field is very complicated and sometimes impossible for complex structures of dielectric sensors.

Fig. 1. Elements of the measurement stand for the determination of stone fruit dielectric properties: (A) – applied custom made dielectric probes of open-ended (OE) and antenna-open-ended (OE-A) types, (B) – respective dimensions in mm, (C) – measurement stand for dielectric measurements.

Fig. 2. Projekt zintegrowanej sondy profilowej wilgotności, temperatury i zasolenia gleby (HF – high frequency, ICs – integrated circuits).
Design of the integrated profile probe for the measurement of soil moisture, temperature and salinity (HF – high frequency, ICs – integrated circuits)