Transferring knowledge on microelectromechanical design - plant embolism sensors for agriculture

Project Summary

Traditional agriculture in karst environments along the Adriatic coast (e.g. wine, olive oil) has always been challenging, due to limited water supply, harsh rocky soils, and seasonal droughts. 

We research advanced sensor systems applied in smart agriculture, focusing on designing low-power, low-cost sensors for non-invasive detection of an early symptom of drought-induced water-stress - embolization of plant's water transport tissues. Such emerging sensor technology integrated in precision irrigation systems would increase food production efficiency, while decreasing the usage of precious water resources in karst. In addition, it is applicable in plant-physiological studies of drought, forestry and wood production. 

State-of-the-art sensors for such purpose can only be designed and fabricated in microelectromechanical systems technology. Croatia houses very limited infrastructure for research on microelectromechanical systems. Primary goal of this project is to boost Croatian research and educational capacities in microelectromechanical systems technology, in the field of low-power sensor design. 

Within this mobility-project, the post-doctoral researcher Dr. Oletić will spend 5 months, starting from July 2019, at the Centre de Nanosciences et de Nanotechnologies near Paris in France, hosted by Ass. Prof. Emile Martincic (department Microsystèmes et Nanobiofluidique). There, Dr. Oletić will receive training in the design, modelling, clean-room processes, fabrication and characterization of microelectromechanical devices.

Also, this visit serves a starting point for collaborative design of micromechanical resonator structures, used as building blocks for passive piezoelectric arrays of frequency-selective ultrasonic emissions sensors for detection of plant embolism. Collaboration with the research group of Prof. Ante Bilušić, from the University of Split, Faculty of Science, specialized in piezoelectric thin film materials will enable sustainability of the proposed research after the end of the visit.


Project Duration

The project duration is 6 months and 12 days, from May 22nd 2019 to December 3rd 2019.

Planned duration of the mobility is 5 months, from July 1st 2019 to November 30th 2019.


Project Team

  • Dinko Oletić, Project Leader, Postdoctoral fellow, University of Zagreb, Faculty of Electrical Engineering and Computing
  • Emile Martincic, Project co-leader @ host institution, Assistant professor, Centre de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Université Paris-Saclay, France
  • Ante Bilušić, Collaborator, University of Split, Full professor, Faculty of Science (PMFST)



This research has been fully supported by Unity through Knowledge Fund under the Grant Agreement No 16/19.

Value of the project supported by the UKF is 64.000,00 HRK.


Dinko Oletic, PhD
University of Zagreb, Faculty of Electrical Engineering and Computing
FER-ZESOI, Unska 3, HR-10000 Zagreb, Croatia
tel: + 385 1 6129 536
e-mail: dinko (dot) oletic (at) fer (dot) hr




Paper published at the DTIP 2020...

A joint conference paper by Dinko Oletić, his host Emile Martincic and colleagues from C2N, titled "Designing Micro-Mechanical Cantilever Resonator Arrays for Wideband Detection of Ultrasonic Xylem Cavitation Emissions Related to Plant Water-Stress", was published at the Design, Test, Integration & Packaging of MEMS/MOEMS (DTIP 2020) conference. This year's conference is organized as a virtual event from 15th to 26th June 2020. The video-presentation by Dinko Oletić will be openly accesible on June, 22nd on the conference's Youtube channel.

Author: Dinko Oletić
Collaboration continued, February 2020

After the project completion, the collaboration was continued by a short visit of Dr. Oletic to C2N between 23th and 29th February 2020. During the visit, team continued experimental work on prototyping micromachining steps. They tested double-sided deep-reactive ion etching fabrication process of resonator's geometry, characterization of resonators' frequency response by optical vibrometry, and further testing of e-beam depositions.

Author: Dinko Oletić
Public lecture at UNIZG-FER

On 10.12.2019 Dr. Oletić held a public lecture at University of Zagreb, Faculty of Elelctrical Engineering, presenting his research outcomes and experiences from his stay at C2N, France, within the UKF "Gaining Experience" programme. The lecture was coorganized and supported by the Croatia's chapter of the IEEE Instrumentation and Measurement Society.

Author: Dinko Oletić
Stay at the C2N, France completed

Dr. Oletić completed his his 5-month stay at the C2N and returned to Zagreb on the November 30th, 2019. The visit was very fruitful, meeting all planned research objectives. It opened a joint research track and many opportunities for future collaboration between the Dr. Oletić's research group from University of Zagreb, FER-ZESOI, and the Prof. Emile Martincic's group at the C2N.

Author: Dinko Oletić
Micro-fabrication activities, November

In the November, Dr. Oletić completed a series of on-going trainings in clean-rooms microfabrication technologies (A2.2): 1) In-depth UV photo-litography training was completed and validated on 08.11., enabling Dr. Oletić the autonomous usage of the C2N's litography facility. 2) Hands-on training in scanning electron microscopy (SEM) and energy-dispersion spectroscopy (EDX) was finished on 27.11., resulting in the validation for autonomous usage. 3) Training in metal depositions, including oxygen-plasma cleaning, electron-beam co-evaporation, chemical lift-off, and profilometry.

The acquired knowledge was used for micro-fabrication activities (A2.3): 1) Photolitographic patterning for micro-fabrication of resonator's geometry by deep-reactive ion etching (DRIE). Wafers were sent for DRIE to the FEMTO-ST Institute, Besancon. 2) Fabrication of the metallic-electrodes by the lift-off process: photolitographic patterning, oxygen-plasma cleaning, electron-beam co-evaporation, lift-off, inspection by optical microscopy, profilometry, and electron microscopy (SEM and EDX). 

Author: Dinko Oletić
Cleanroom training, October

During the October, Dinko Oletić started his training on MEMS photolitography (A2.2). It began on 10.10. by a guided tour through the C2N's cleanroom laboratory space for UV-litography, focusing on workspace-organization, handling of materials, and operating procedures for the UV-exposure equipment. Litography training continued on 16.10. focusing on usage of chemical processes (sustrate preparation, application of photoresists, post-exposure development). In addition, on 14.10. Dr. Oletić received training on usage of the cleanrooms's chemical processing area (substrate cleaning, wet-etching, lift-off...).

Photolitography masks have arrived on 16.10., enabling the team to start organizing the cleanroom fabrication activities (A2.3). Discussing the plans on depostions of thin-film piezoelectrics, prof. Ante Bilušić (PMF Split) helped the project team to extend the network of contacts.

Attending the 2019 IEEE Sensors Conference in Montreal 27-30.10. attracted a lot of interest in the project.

Author: Dinko Oletić
Design phase complete,...

During the September, Dr. Martincic and Dr. Oletić finished the design of photolithography masks (A1.3). On 26.09. 2019 masks were sent for fabrication. Once done, they will enable the team to start the clean-room fabrication (A2.3) of the piezoelectric micromechanical resonators, they have designed during this summer.

On 17.09.2019 Dinko Oletić attended the lecture "Mechanics of thin films and nanostructures" by Prof. Alain Bosseboeuf. Lecture covered: elastic properties of isotropic and anisotropic thin-film materials, origins, measurement of residual stress, and its  effects on mechanics of beams, membranes and bridge microstructures.

Also, on 19.09.2019 Dr. Oletić participated the cleanroom chemical safety workshop. There he received training on risks, safe operative procedures in cleanroom, guidelines for handling and disposition of chemicals, and safety procedures in case of exposure to chemicals.

Author: Dinko Oletić
Project activities, August

Based on the design requirements assessed by FEM modelling (in A1.1), available equipment and materials at C2N,  Dr. Martincic and Dr. Oletić developed a plan of the technological processing steps, required for cleanroom fabrication of the simulated MEMS ultrasonic piezoelectric resonator arrays (activity A1.2). Based on this, Dr. Oletić started designing photolitographic masks (A1.3). 

Furthermore, on August 21st, Dr. Fabien Bayle gave Dr. Oletić tour of clean-room's scanning electron microscopy (SEM) equipment. He showed Dr. Oletić the basics of SEM for surface visualization and characterization. Also, he demonstrated the usage of SEM for energy dispersive X-ray spectroscopy (EDS/EDX) analysis of material's chemical composition.

Author: Dinko Oletić
MEMS technological training...

On July 8th, Dr. Oletić attended the official security training, organized by the C2N clean-room maintenance staff. Training, consisted of a lecture describing organization of the C2N's clean-room technological fascility, major security procedures, and the guided tour of the clean-room spaces (activity A2.1).

Later, on July 10th, Dr. Oletić received hands-on training in optical methods for MEMS resonator characterization: interferometry, vibrometry, and microscope-stroboscopy from Prof. Alain Bosseboeuf. 

Author: Dinko Oletić
C2N's annual barbecue!

On Friday July 5th, Centre de Nanosciences et de Nanotechnologies organized its traditional annual networking event - the C2N's barbecue. This was an excelent networking oportunity to meet over 160 researchers from C2N's four departments: Microsystems and nanobiofluidics, Nanoelectronics, Photonics, and Materials.

Author: Dinko Oletić
Dinko Oletić started his stay at the...

On the July 1st 2019 postdoctoral researcher Dr. Dinko Oletić departed from Zagreb to Centre de Nanosciences et de Nanotechnologies (C2N) in Palaiseau, near Paris, France, for his 5-month visit. There he was welcomed by his host, Assistant professor Emile Martincic, at the Microsystems and nanobiofluidics department. During the July, Prof. Martincic introduced Dr. Oletić to the first step in MEMS sensor design process: analytical and finite-element modelling of piezoelectric micromechanical resonators (project activity A1.1).

Author: Dinko Oletić