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The measurement of biological tissues’ dielectric properties plays a crucial role in determining the state of health, and recent studies have reported microwave biosensing to be an innovative method with great potential in this field. Research has been conducted from the tissue level to the cellular level but, to date, cellular adhesion has never been considered. In addition, conventional systems for diagnosing tumor aggressiveness, such as a biopsy, are rather expensive and invasive. Here, we propose a novel microwave approach for biosensing adherent cancer cells with different malignancy degrees. A circular patch resonator was designed adjusting its structure to a standard Petri dish and a network analyzer was employed. Then, the resonator was realized and used to test two groups of different cancer cell lines, based on various tumor types and aggressiveness: low- and high-aggressive osteosarcoma cell lines (SaOS-2 and 143B, respectively), and low- and high-aggressive breast cancer cell lines (MCF-7 and MDA-MB-231, respectively). The experimental results showed that the sensitivity of the sensor was high, in particular when measuring the resonant frequency. Finally, the sensor showed a good ability to distinguish low-metastatic and high-metastatic cells, paving the way to the development of more complex measurement systems for noninvasive tissue diagnosis.

In this work, the dielectric permittivity of four kinds of wood (Fir, Poplar, Oak, and Beech Tree), used in Italian Artworks and structures, was characterized at different humidity levels. Measurements were carried out using three different probes connected to a bench vector network analyzer: a standard WR90 X-band waveguide, a WR430 waveguide, and an open-ended coaxial probe. In particular, we investigated the dispersion model for the four wood species, showing how a log-fit model of the open-ended data presents a determination coefficient R2 > 0.990 in the 1–12 GHz frequency range. This result has proven helpful to fill the frequency gap between the measurements obtained at different water contents with the two waveguide probes showing an R2 > 0.93. Furthermore, correlating the log-fit vertical shift with the water content, it was possible to find a calibration curve with a linear characteristic. These experimental results will be helpful for on-site non-invasive water monitoring of wooden artworks or structures. Moreover, the final results show how the open-ended coaxial probe, with a measurement deviation lower than 7% from the waveguide measurements, may be used directly as a non-invasive sensor for on-site measurements.

A low-cost and portable reflectometric system was described to correlate the water content inside building material with the resonance frequency of a planar probe. An inexpensive planar patch resonator was realized, and a high sensitivity load cell was developed to investigate the external force effect on the resonance frequency shift. Regarding the material under test, four stones commonly employed in Italy Cultural Heritage buildings were used: Pietra Gentile, Leccese, Carparo, and Tuff. Measurements were carried out at different water content values and were performed using a portable vector network analyzer. Two different trials were carried out ten times for each moisture level: with an unknown handheld force exerted on the probe and using the load cell to ensure a repeatable force. Results showed that a repeatable applied force guaranteed more reproducible measurements. The achieved humidity/frequency calibration curves can be used, in practice, for non-invasive on-site water content monitoring of historic structures.

Monitoring of environmental parameters is necessary to preserve materials, identify causes of degradation, and quantify their effects, as a function of time. In this research, we propose a measuring unit and present an example of collected data. The unit is based on an ATmega328P microcontroller, gathering signals from: a 9-axis MIMU; a sensor for temperature and relative humidity; and three gas detection miniature boards (NO, NO2 and SO2). The aim of the project is to monitor the effects of different factors: (i) seasonal thermal variations; (ii) dynamic response of the structure and (iii) gaseous pollutant concentration. The developed system allows for a prioritization of intervention both for management and interventions planning, in terms of restoration, consolidation, and conservation. The experimental setup used to evaluate the accuracy of MIMU system highlighted a relative error on shock acceleration measurement, in term of percent root mean square error, lower than 0.36 for the sinusoidal input, and 0.49 for cardinal sin input, with an average accuracy in the principal peak reconstruction lower than 2% in the chosen frequency range (5 Hz to 50 Hz). Data collected in situ showed a maximum frequency of vibration, at ground level, equal to 40 Hz with a peak of 8 mm/s. The gas detection and temperature/humidity boards showed data comparable with the closest certified ARPA system device.

In this paper, a new methodology for measuring the cracking in the field of Structural Health Monitoring (SHM) of cultural heritage, is presented. The minimum invasiveness of this methodology permits to preserve the aesthetic appearance, a fundamental requirement in monitoring of cultural heritage. The core of the acquisition system is composed by two small adhesive tags to be attached on the artwork surface, and a high-resolution camera acquiring images of the tags. The relative distance between the optical tags for determining is determined using advanced least-squares fitting of quadratic curves and surfaces algorithms for the objective function. Here, the bi-dimensional Gaussian as objective function has been taken into account, in order to find the best configuration for determining the fitting parameters, useful for the SHM. We ran a simulation for tuning fitting algorithm parameters. Then we validated the methodology through an experimental session.

Wireless Sensor Network (WSN) has been adopted in many contexts, such as healthcare or industry. In museum scenarios, WSN has been introduced for environmental monitoring, to control temperature and relative humidity. Nowadays, the development of low-cost micro-scale sensing units, opened to new possibilities for WSN development, enlarging the set of feasible measurements to gaseous pollutant concentration, relative humidity, temperature, light intensity, air flow, or vibration.This work is part of the overarching goal of developing a low-cost and minimally invasive WSN designed for a museum scenario. The proposed WSN node, based on a ZigBee standard, gathers signals provided by: a 9-axis MIMU, a sensor for temperature and relative humidity, and three gas detection boards. In this paper, specifically, we present performances of the WSN node in detecting: structure tilt, vibrations, and daily cycle of humidity, temperature, and gas deposition.