A stable environment is critical for preserving product quality in industries such as pharmaceuticals and perishable goods logistics. While current RFID-based sensors enable wireless monitoring of temperature and moisture, they lack the ability to record threshold violations without continuous reader power or battery-supported logging. This paper presents AntSense, a battery-free RFID sensor that leverages stimuli-responsive structures to physically record environment violation events during the transit even when there is no reader available. When exposed to temperature or moisture beyond thresholds, memory alloy or solvable materials undergo irreversible geometric deformation, altering the integrated antenna’s characteristics. These changes remain detectable via standard RFID readers even after environment conditions normalize, enabling verification of transit integrity. Our prototype evaluations demonstrate reliable detection of threshold violations in real-world scenarios. By combining passive operation with persistent event recording, AntSense offers a scalable solution for supply chain monitoring without compromising the maintenance-free advantages of RFID technology.

The objective of this paper is to develop a noncontact, noninvasive system for detecting and monitoring subcutaneous infection occurring at the tissue and osseointegrated prosthesis interface. It is known that the local pH of tissue can change due to infection. Therefore, the sensing system integrates two parts, namely, pH-sensitive thin films that can be coated onto prosthesis surfaces prior to them being implanted and an electrical capacitance tomography (ECT) algorithm that can reconstruct the spatial permittivity distribution of a region of space in a noncontact fashion. First, a thin film pH sensor was fabricated by spray coating, and tests confirmed that the film exhibited changes in its permittivity due to pH. Second, the ECT forward and inverse problems were implemented. Third, an aluminum rod was employed as a representative phantom of an osseointegrated prosthesis and then spray coated with the pH sensor. Finally, the film-coated phantom was immersed in different pH buffers, dried, and subjected to ECT interrogation and spatial permittivity reconstruction. The results validated that ECT was able to detect and localize permittivity variations correlated to pH changes.

Concrete and other cementitious composites used in civil infrastructure are prone to many forms of damage. For example, cracks could occur and propagate to cause catastrophic component or system-level failure. Therefore, the objective of this study was to nano-engineer a self-sensing cementitious composite that could detect and locate damage. Integration of multi-walled carbon nanotubes (MWNTs) in the mortar mix design and during casting enhanced the electromechanical or sensing properties of the cementitious composites. Instead of directly dispersing MWNTs in the cement matrix, the cement-particle interface was modified using spray-coated MWNT-latex thin films deposited directly onto dry sand particles prior to mortar casting. This procedure preserved MWNT dispersions within the thin film architecture, used minimal amounts of MWNTs, was scalable, and provided dramatic sensing performance enhancements. The mechanical and electromechanical properties of mortar specimens were characterized using compressive cyclic load tests. Furthermore, an electrical resistance tomography (ERT) algorithm was used for mapping mortar specimens' spatial resistance distributions. Since their resistance was precalibrated to strain, localized changes in calculated resistance indicated damage. Spatial damage detection was validated by drilling holes in various locations in cementitious composite plates and then by mapping resistance distributions using ERT.