Thermosensitive Sensors Research Articles

Develоpment оf а thermоcаtаlytic sensоr fоr mоnitоring ethyl аlcоhоl vаpоrs in humаn exhаled аir аnd prоcess gаses

In this work, highly sensitive thermocatalytic methods and selective devices for observe the content of ethanol vapor in the air and waste industrial gas mixtures have been developed. The main indicators of the developed sensors for the determination of ethanol were assessed. The possibility of creating highly sensitive, selective sensors using measuring and compensation thermosensitive sensor elements containing catalysts of varying activity in relation to the components of complex gas-air mixtures has been experimentally confirmed. The created sensors allow the selective determination of ethanol vapor in a mixture of various gases. The scope of application of the developed sensors is environmental monitoring of atmospheric air and process gases, pre-trip and pre-shift examination of drivers, analysis in treatment rooms, clinics and clinics to accurately determine the clinical condition of patients, etc. Sensors can also be used as a means of self-monitoring.

Polyampholyte Polymers‐Based Sensors: A Review on Stimuli and Applications

AbstractPolyampholytes are a specific type of zwitterionic materials composed of monomers with both positive and negative charges. These materials can be synthesized through various methods, such as free radical, anionic, or cationic polymerization, or by modifying existing polymers through postpolymerization processes. Polyampholytes possess unique properties that make them attractive for a wide range of applications, particularly in sensor technology. They can undergo conformational changes in response to external stimuli like pH variations, temperature fluctuations, or changes in salt concentration. These properties have led to their application in biosensors, salt and ion sensors, pH sensors, fluorescence‐based sensors, strain sensors, and thermosensitive sensors. It is worth noting that in some cases polyampholytes can respond to multiple stimuli simultaneously. Overall, polyampholytes are drawing great attention for their excellent mechanical properties including self‐healing, high toughness, and fatigue resistance. Thus, this review is focused on advances that are made to develop polyampholyte polymer‐based sensors in different applications.

Multifunctional MXene-based fire alarm wallpaper with sandwich-like structure for enhanced fire safety and prevention

Design and development of multifunctional fire-resistant and fire alarm wallpaper (FAW) that can simultaneously hold early fire warning function and the ability to inhibit flame propagation is urgently required to boost the fire safety of combustible materials in public security. Herein, a flexible sandwich-like and nacre-biomimetic FAW was fabricated by using renewable lignocellulose nanofibrils (LCNF) and MXene thermosensitive sensor via a vacuum-assisted alternate self-assembly method. The FAW achieved ultrasensitive fire early warning response because of the synergistic effect of the insulating LCNF layers and highly conductive MXene with hierarchical structure sandwiched between LCNF layers. Furthermore, owing to the ultrafast catalytic char formation and intumescent flame retardant effect of ammonium polyphosphate (APP), the trigger sensitivity and thermal oxidation capacity of the FAW (LCNF-15) were greatly optimized by adding 15 % APP in the LCNF layer, resulting in a superior fire alarm response (0.32 s) and a continuous alarm signal (about 3073.0 s) under a flame attack. Besides, the LCNF-15 also exhibited good flexibility, ideal cyclic warning performance, excellent heat insulation ability and strong char-forming properties in a fire. The sandwich-like strategy offers a new platform for the construction of MXene-based multifunctional FAW, which is of great value in broadly addressing the fire hazard problem of traditional wallpapers.

Biomass-based flexible fire warning sensor with excellent flame retardancy and sensitivity

Traditional fire warning sensors usually work under directly fire attack or relatively high temperature with short service life and poor sensitivity. Therefore, the preparation of thermosensitive sensors with excellent fire resistance, sustainability and sensitive fire detection function is critical. In this work, biomass-based carbon nanofibers (CNFs) are designed and constructed by phosphating treatment and polyaniline modification co-functionalization strategy. The introduction of lignin molecules significantly improves the compatibility and spinnability of polyaniline and biomass-based spinning aid, thus effectively reducing the generation of the bead like defects and fine fibrous morphologies. The optimized CNFs exhibit good structure stability, electrical conductivity and sensitivity (responsive temperature 100 ℃, thermosensitive sensor response about 2 s, and sustained working time at least 5 min in the flame). Furthermore, the specific capacitance of biomass-based CNFs reaches 358F/g, energy density of 49.7 Wh/kg at a power density of 542.4 W/kg. This work provides a novel strategy and paradigm for achieving excellent flame resistance and ideal fire warning sensor of biomass-based materials. The resulting biomass-based carbon nanofibers can be processed into intelligent thermosensitive sensor with various shapes and have a broad application prospect in flexible devices and wearable electrodes fields.

Fluorinated carbon dots/carboxyl methyl cellulose sodium composite with a temperature-sensitive fluorescence/phosphorescence applicable for anti-counterfeiting marking

Carbon dots (CDs) have attracted extensive attention due to their excellent optical properties, especially in the tunable photoluminescence (PL) (including fluorescence, delayed fluorescence and phosphorescence) and high photostability. However, the thermal stimuli-responsive PL from CDs based materials is still rare reported so far. In this work, we report a facile, large-scale synthesis of a polymer nanocomposite containing fluorinated carbon dots (FCDs) by using a commercial, water-soluble polymer carboxyl methyl cellulose sodium (CMCNa) as a stabilizing matrix. The as-synthesized FCDs-CMCNa shows both solid-state fluorescence and room temperature phosphorescence (RTP). More interestingly, with temperature decreasing from 300 to 90 K, the FCDs-CMCNa presents a peculiar temperature-sensitive optical property that its fluorescence/phosphorescence intensity both increase with temperature decreasing to a turning point of 150 K and then decline gradually as temperature decreasing to 90 K. This peculiar temperature-sensitive optical property of FCDs-CMCNa can be applied in advanced anti-counterfeiting, information encryption and thermo-sensitive sensors.

Self-powered forest fire alarm system based on impedance matching effect between triboelectric nanogenerator and thermosensitive sensor

Abstract As worldwide forest fire frequently causes a serious threat to forest resources and global climate change, novel early forest fire monitoring and detection technologies are urgently required to explore. Herein, a self-powered forest fire alarm system (FFAS) is proposed by coupling thermosensitive effect and triboelectric effect as an aim of effective forest fire monitoring and detecting. The FFAS is fabricated as a self-powered early forest fire monitoring and detection system by connecting a spherical free-standingmode triboelectric nanogenerator (S-TENG) as power source with polydopamine-modified graphene oxide (P-GO) as thermosensitive sensor and commercial LEDs as alarm. When encountering an open fire or abnormal high temperature the thermosensitive sensor based on P-GO can be in-situ thermally reduced, inducing an obvious transition in electrical resistance. Thus, the output voltage of S-TENG can be tuned by the impedance matching effect between special output characteristics of TENG and working status of thermosensitive sensor, and then can directly light up the LEDs as alarm. Furthermore, the FFAS achieves a low temperature response (160 °C), rapid response time (~3 s), and especially no external power supply. Consequently, the FFAS based on impedance matching effect between TENG and thermosensitive sensor would provide a real-time, rapidly responsive, and self-powered monitoring strategy for the early forest fire warning and detection.

Fire Alarm Wallpaper Based on Fire-Resistant Hydroxyapatite Nanowire Inorganic Paper and Graphene Oxide Thermosensitive Sensor.

Wallpaper with multiple functions, such as fire resistance and an automatic alarm in fire disasters, will be attractive for the interior decoration of houses. Herein, we report a smart fire alarm wallpaper prepared using fire-resistant inorganic paper based on ultralong hydroxyapatite nanowires (HNs) and graphene oxide (GO) thermosensitive sensors. At room temperature, the GO thermosensitive sensor is in a state of electrical insulation; however, it becomes electrically conductive at high temperatures. In a fire disaster, high temperature will rapidly remove the oxygen-containing groups of GO, leading to the transformation process of GO from an electrically insulated state into an electrically conductive one. In this way, the alarm lamp and alarm buzzer connected with the GO thermosensitive sensor will send out the alerts to people immediately for taking emergency actions. After the surface modification with polydopamine of GO (PGO), the sensitivity and flame retardancy of the GO thermosensitive sensor are further improved, resulting in a low responsive temperature (126.9 °C), fast response (2 s), and sustained working time in the flame (at least 5 min). Compared with combustible commercial wallpaper, the smart fire alarm wallpaper based on HNs and GO (or PGO) is superior owing to excellent nonflammability and high-temperature resistance of HNs, which can protect the GO (or PGO) thermosensitive sensor from the flames. The smart fire alarm wallpaper can be processed into various shapes, dyed with different colors, and printed with the commercial printer and thus has promising applications in high-safety interior decoration of houses.

Relationship between nano-architectured Ti1−x Cu x thin film and electrical resistivity for resistance temperature detectors

Ti1−x Cu x thin films were produced by the glancing angle deposition technique (GLAD) for resistance temperature measurements. The deposition angle was fixed at α = 0° to growth columnar structures and α = 45° to growth zigzag structures. The Ti-to-Cu atomic concentration was tuned from 0 to 100 at.% of Cu in order to optimize the temperature coefficient of resistance (TCR) value. Increasing the amount of Cu in the Ti1−x Cu x thin films, the electrical conductivity was gradually changed from 4.35 to 7.87 × 105 Ω−1 m−1. After thermal “stabilization,” the zigzag structures of Ti1−x Cu x films induce strong variation of the thermosensitive response of the materials and exhibited a reversible resistivity versus temperature between 35 and 200 °C. The results reveal that the microstructure has an evident influence on the overall response of the films, leading to values of TCR of 8.73 × 10−3 °C−1 for pure copper films and of 4.38 × 10−3 °C−1 for a films of composition Ti0.49Cu0.51. These values are very close to the ones reported for the bulk platinum (3.93 × 10−3 °C−1), which is known to be one of the best material available for these kind of temperature-related applications. The non-existence of hysteresis in the electrical response of consecutive heating and cooling steps indicates the viability of these nanostructured zigzag materials to be used as thermosensitive sensors.