Microdroplet-Based Organic Vapour Sensor on a Disposable GO-Chitosan Flexible Substrate

Abstract

With rising hazardous organic vapours in the environment, the detection of volatile organic vapour compounds (VOCs) is becoming important. To this end, this paper presents a conductive droplet-based disposable sensor. Unlike conventional sensors, the droplet system is easily replaceable and is capable of detecting multiple vapours based on surface tension gradient. The chemiresistive sensor presented here is fabricated on 2.5 µm thick ultra-flexible graphene oxide-chitosan (GOC) with Pt electrodes having 60 µm gap. The electrostatic interaction and strong hydrogen bonds between GO and polysaccharide groups in chitosan provide tunable hydrophobicity and stability to the droplet. With a conductive droplet of ∼10 µL of aq. NaCl as an active sensing material dispensed between the Pt electrodes, it was observed that the droplet showed 14-21% change in resistance in the presence of VOCs. A read-out circuit was also designed to get the data from the droplet sensor. The response time for the presented sensor (3-4 seconds) is significantly better than its solid-state sensor counterparts. With attractive features such as disposability, affordability and fast response the presented sensor will find applications in industrial environments, laboratories, health centres, and biomedical devices.

Disposable Electrochemical Sensor Using Graphene Oxide–Chitosan Modified Carbon-Based Electrodes for the Detection of Tyrosine

“…Considering this, POC sensing tools that are suitable for onsite measurements, where affordable, user-friendly, and disposable devices are preferred, are in critical demand. Relatively simple fabrication processes, fast and label-free detection, portability, the possibility of miniaturization, high sensitivity and low limits of detection, etc., are central to the development of these POCT devices [21,22]. Flexibility, and biocompatibility are also crucial factors for the development of wearable systems with conformable form factors that interface with human skin or the curvature of soft biological materials [23][24][25].…”

“…GO and CS were chosen for the sensitive film due to their natural abundance, excellent electrochemical sensing properties, good chemical stability, flexibility, and excellent film-forming capability. Furthermore, the affordable, biocompatible, eco-friendly, and biodegradable nature of this nanocomposite, as highlighted in our previous work, make GO and CS ideal candidates for affordable, disposable devices suitable for wearable POCT devices [5,22,46,47]. For the electrochemical detection of Tyr, an Ag/AgCl (3.0MNaCl solution) reference electrode and a Pt wire counter electrode were used, in addition to the GO-CS-SPCE.…”

Flexible Strain and Temperature Sensing NFC Tag for Smart Food Packaging Applications

“…[1], [2] These advances have also enabled the use of robots during various stages of agriculture or farm produce, such as fruit picking and packaging [3]- [5]. To this end, several physical and chemical sensors have been developed to gather information about temperature [6]- [8], pressure [9]- [11], strain [12]- [14], humidity [15], [16], pH [17], [18], volatile organic compounds (VOCs) [19], etc. Further, the advances in nanotechnology and Printed Electronics (PE) have unlocked interesting avenues for sensing using various functional and degradable materials in applications such as smart labels for food, pharmaceutical and wearables [20]- [24].…”

NFC based Polymer Strain Sensor for Smart Packaging

“…The safety of goods during transportation is a key step particularly for food packages, as even slight damage could raise health and safety concerns [1]. For this reason, several types of sensors such as pH [2,3], biomolecules [4][5][6], humidity [7], VOCs [8,9] etc. have been explored with self-powered or power storage means such as supercapacitor and battery.…”