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14 pages, 7117 KiB

Open AccessArticle

Smart Packaging for Food Spoilage Assessment Based on Hibiscus sabdariffa L. Anthocyanin-Loaded Chitosan Films

by Arezou Khezerlou, Milad Tavassoli, Mahmood Alizadeh Sani, Ali Ehsani and David Julian McClements

J. Compos. Sci. 2023, 7(10), 404; https://doi.org/10.3390/jcs7100404 - 24 Sep 2023

Cited by 34 | Viewed by 5705

An on-package colorimetric label was fabricated using Hibiscus sabdariffa L. anthocyanin as a freshness indicator because its color depends on pH. The anthocyanins were embedded within a chitosan matrix. The colorimetric labels were applied to estimate the spoilage of fish food during storage at 25 °C for 3 days. According to scanning electron microscopy results, the inclusion of the anthocyanins in chitosan matrix resulted in formation dense and uniform film. The chitosan colorimetric labels had acceptable thicknesses (78–85 µm), moisture contents (14–16%), swelling indices (84–102%), water vapor permeabilities (3.0–3.2 × 10⁻¹¹ g m/m² s Pa), tensile strengths (11.3–12.3 MPa), and elongation at breaks (14–39%). It is noteworthy that the label can distinguish fish spoilage by color turn from light brown (fresh) to grayish (spoiled) by the naked-eye, due to alterations in the pH content and formation of volatile basic nitrogen during storage. Our results indicate that all-natural color labels can be an effective method to monitor the fish spoilage during storage, which may improve food quality and sustainability. Full article

(This article belongs to the Section Composites Applications)

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15 pages, 10939 KiB

Open AccessArticle

3D-Printed PLA Molds for Natural Composites: Mechanical Properties of Green Wax-Based Composites

by Mihai Alin Pop, Mihaela Cosnita, Cătălin Croitoru, Sebastian Marian Zaharia, Simona Matei and Cosmin Spîrchez

Polymers 2023, 15(11), 2487; https://doi.org/10.3390/polym15112487 - 28 May 2023

Cited by 6 | Viewed by 3582

Abstract

The first part of this paper is dedicated to obtaining 3D-printed molds using poly lactic acid (PLA) incorporating specific patterns, which have the potential to serve as the foundation for sound-absorbing panels for various industries and aviation. The molding production process was utilized to create all-natural environmentally friendly composites. These composites mainly comprise paper, beeswax, and fir resin, including automotive function as the matrices and binders. In addition, fillers, such as fir needles, rice flour, and Equisetum arvense (horsetail) powder, were added in varying amounts to achieve the desired properties. The mechanical properties of the resulting green composites, including impact and compressive strength, as well as maximum bending force value, were evaluated. The morphology and internal structure of the fractured samples were analyzed using scanning electron microscopy (SEM) and an optical microscopy. The highest impact strength was measured for the composites with beeswax, fir needles, recyclable paper, and beeswax fir resin and recyclable paper, 19.42 and 19.32 kJ/m², respectively, while the highest compressive strength was 4 MPa for the beeswax and horsetail-based green composite. Natural-material-based composites exhibited 60% higher mechanical performance compared to similar commercial products used in the automotive industry. Full article

(This article belongs to the Special Issue Polymer Waste Recycling and Management II)

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17 pages, 762 KiB

Open AccessArticle

A 24-GHz Front-End Integrated on a Multilayer Cellulose-Based Substrate for Doppler Radar Sensors

by Federico Alimenti, Valentina Palazzi, Chiara Mariotti, Marco Virili, Giulia Orecchini, Stefania Bonafoni, Luca Roselli and Paolo Mezzanotte

Sensors 2017, 17(9), 2090; https://doi.org/10.3390/s17092090 - 12 Sep 2017

Cited by 14 | Viewed by 8925

Abstract

This paper presents a miniaturized Doppler radar that can be used as a motion sensor for low-cost Internet of things (IoT) applications. For the first time, a radar front-end and its antenna are integrated on a multilayer cellulose-based substrate, built-up by alternating paper, glue and metal layers. The circuit exploits a distributed microstrip structure that is realized using a copper adhesive laminate, so as to obtain a low-loss conductor. The radar operates at 24 GHz and transmits 5 mW of power. The antenna has a gain of 7.4 dBi and features a half power beam-width of 48 degrees. The sensor, that is just the size of a stamp, is able to detect the movement of a walking person up to 10 m in distance, while a minimum speed of 50 mm/s up to 3 m is clearly measured. Beyond this specific result, the present paper demonstrates that the attractive features of cellulose, including ultra-low cost and eco-friendliness (i.e., recyclability and biodegradability), can even be exploited for the realization of future high-frequency hardware. This opens opens the door to the implementation on cellulose of devices and systems which make up the “sensing layer” at the base of the IoT ecosystem. Full article

(This article belongs to the Special Issue New Generation Sensors Enabling and Fostering IoT)

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14 pages, 551 KiB

Open AccessArticle

Communication and Sensing Circuits on Cellulose

by Federico Alimenti, Chiara Mariotti, Valentina Palazzi, Marco Virili, Giulia Orecchini, Paolo Mezzanotte and Luca Roselli

J. Low Power Electron. Appl. 2015, 5(3), 151-164; https://doi.org/10.3390/jlpea5030151 - 25 Jun 2015

Cited by 18 | Viewed by 8988

Abstract

This paper proposes a review of several circuits for communication and wireless sensing applications implemented on cellulose-based materials. These circuits have been developed during the last years exploiting the adhesive copper laminate method. Such a technique relies on a copper adhesive tape that is shaped by a photo-lithographic process and then transferred to the hosting substrate (i.e., paper) by means of a sacrificial layer. The presented circuits span from UHF oscillators to a mixer working at 24 GHz and constitute an almost complete set of building blocks that can be applied to a huge variety communication apparatuses. Each circuit is validated experimentally showing performance comparable with the state-of-the-art. This paper demonstrates that circuits on cellulose are capable of operating at record frequencies and that ultra- low cost, green i.e., recyclable and biodegradable) materials can be a viable solution to realize high frequency hardware for the upcoming Internet of Things (IoT) era. Full article

(This article belongs to the Special Issue Low-Power Systems on Chip Enabling Internet of Things)

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