Excellent Thermal Sensitivity Research Articles

Tailoring Energy Transfer in Mixed Eu/Tb Metal-Organic Frameworks for Ratiometric Temperature Sensing.

Eu/Tb metal-organic frameworks (Eu/Tb-MOFs), exhibiting Eu3+ and Tb3+ emissions, stand out as some of the most fascinating luminescent thermometers. As the relative thermal sensitivity model is limited to its lack of precision for fitting ratio of Eu3+ and Tb3+ emissions, accurately predicting the sensing performance of Eu/Tb-MOFs remains a significant challenge. Herein, we report a series of luminescent Eu/Tb-MOF thermometers, EuxTb1-xL, with excellent thermal sensitivity around physiological levels, achieved through the tuning energy transfer from ligands to Eu3+ and Tb3+ and between the Ln ions. It was found that the singlet lowest-energy excited state (S1) of the ligand and the higher triplet energy level (Tn) are crucial in the energy transfer processes of ligand→Tb3+ and ligand→Eu3+. This enables EuxTb1-xL to serve as an effective platform for exploring the impact of these energy transfer processes on the temperature-sensing properties of luminescent Eu/Tb-MOF thermometers. The relative thermal sensitivity is comparable to that of dual-center MOF-based luminescent thermometers operating at physiological levels. This study provides valuable insights into the design of new Eu/Tb thermometers and the accurate prediction of their sensing performance.

Plasmon-emitter coupling in cytosine-rich hairpin DNA-templated silver nanoclusters: Thermal reversibility, white light emission, and dynamics inside live cells.

Bio-templated luminescent noble metal nanoclusters (NCs) have attracted great attention for their intriguing physicochemical properties. Continuous efforts are being made to prepare NCs with high fluorescence quantum yield (QY), good biocompatibility, and tunable emission properties for their widespread practical applications as new-generation environment-friendly photoluminescent materials in materials chemistry and biological systems. Herein, we explored the unique photophysical properties of silver nanoclusters (AgNCs) templated by cytosine-rich customized hairpin DNA. Our results indicate that a 36-nucleotide containing hairpin DNA with 20 cytosine (C20) in the loop can encapsulate photostable red-emitting AgNCs with an absolute QY of ∼24%. The luminescent properties in these DNA-templated AgNCs were found to be linked to the coupling between the surface plasmon and the emitter. These AgNCs exhibited excellent thermal sensitivity and were employed to produce high-quality white light emission with an impressive color rendering index of 90 in the presence of dansyl chloride. In addition, the as-prepared luminescent AgNCs possessing excellent biocompatibility can effectively mark the nuclear region of HeLa cells and can be employed as a luminescent probe to monitor the cellular dynamics at a single molecular resolution.

Laser-induced changes on the upconversion luminescence properties of BiF3:Yb,Er nanoparticles

BiF3 nanoparticles doped with Yb3+ and Er3+ ions in varying ratios were prepared by co-precipitation method and its upconversion luminescence (UCL) properties were investigated in detail before and after high-intensity laser treatment. Green-to-red ratio (GRR) of luminescence from cubic-BiF3:Yb,Er nanoparticles is found to increase with an increase in laser power for as prepared sample. Unlike this, for conventional Yb,Er doped upconversion nanoparticles (UCNPs) such as cubic NaYF4:Yb,Er and hexagonal-NaYF4:Yb,Er, a decrease in GRR values is observed with an increase in laser power. This has been explained based on the reduced extent of Er3+-Er3+ interaction in BiF3:Yb,Er nanoparticles compared to that existing in cubic and hexagonal forms of NaYF4:Yb,Er, nanoparticles. Reduced interaction is brought about by higher lattice parameter of BiF3 host compared to the NaYF4 host which leads to a lesser extent of cross-relaxation in the former host thereby favoring the population of 4S3/2 and 2H11/2 levels of Er3+. Effect of high-intensity laser (180W/cm2) irradiation on BiF3:Yb,Er nanoparticles resulted in an irreversible five-fold increase in upconversion luminescence intensity and this is attributed to combined effect of partial conversion of BiF3 to cubic Bi2O3 and removal of adsorbed water molecules. These inferences are confirmed by XRD and TEM measurements carried out on laser-treated sample. Improved luminescence intensity from the laser-treated sample is also confirmed by the high-contrast clear images obtained from impressions made using high-intensity laser irradiation on BiF3:Yb,Er nanoparticles. BiF3:Yb,Er nanoparticles showed an excellent thermal sensitivity of 0.3% K−1 at room temperature and the value is comparable with that of conventional β-NaYF4:Yb,Er nanoparticles.

Antimony Sulfoiodide‐Based Energy Harvesting and Self‐Powered Temperature Detection

The ferroelectric‐semiconductor behavior of antimony sulfoiodide (SbSI) has opened up the material as a base for energy‐harvesting devices. Specifically, SbSI has drawn much attention for pyroelectric energy harvesting and thermal sensing with outstanding electrothermal properties. This work investigates the thermistor properties of an SbSI material and presents the development of an SbSI nanorod/Kapton‐based triboelectric nanogenerator (TENG) for effective energy harvesting and temperature sensing. The TENG based on SbSI/ Kapton operating in vertical contact separation mode delivers a peak‐to‐peak voltage of 90 V and a current of 1510 nA, respectively. Introducing SbSI nanorods for TENG opens the possibility of extending the conventional triboelectric series. The electrical and dielectric properties of the SbSI nanorods are investigated. SbSI exhibits a highly linear temperature coefficient of resistance (TCR) of −0.026 °C−1, making it an excellent candidate material for a thermistor. In addition, the material exhibits an excellent thermal sensitivity (β20/80 = 1612.1 K). For demonstration, the SbSI thermistor is connected with TENG, and the outputs at various temperatures are analyzed for self‐powered temperature sensing. This capability allows for efficient temperature monitoring without relying on external power sources, advancing remote, and autonomous sensing applications.

A novel ultrahigh-sensitive optical thermometer based on inverse thermal responses of Nd3+ and Yb3+ emissions in BaGd2(MoO4)4 phosphor

Nowadays, lots of efforts have been vested on the exploitation of novel luminescent thermometric materials to achieve remote temperature readout with ultra-high sensitivity and sub-degree resolution. Herein, the BaGd2(MoO4)4: Yb3+, Nd3+ phosphors were successfully prepared via a solid-state reaction method, and their concentration/temperature-dependent luminescence behaviors were investigated systematically. Upon 980 nm excitation, the photoluminescence (PL) spectra consisted of three emission bands centered at 754 nm, 805 nm and 872 nm from Nd3+, together with an emission band peaked at 1008 nm from Yb3+. As the temperature elevated, the Yb3+: 2F5/2 → 2F7/2 emission weakened sharply, whereas the promoted phonon-assisted energy transfer process from Yb3+ to Nd3+ and excited-state absorption process of Nd3+ led to an intense thermal enhancement of the Nd3+: 4Fj → 4I9/2 (j = 7/2, 5/2, 3/2) transitions. Moreover, the thermally enhancing factor was found to depend on the Nd3+ concentration. By utilizing the luminescence intensity ratio (LIR) technique, the temperature sensing behaviors based on thermally coupled levels (Nd3+: 4Fj, j = 7/2, 5/2, 3/2) and non-thermally coupled levels (Nd3+: 4Fj and Yb3+: 2F5/2) were studied at the different doping concentrations. When the temperature sensing was based on LIR between Nd3+: 4F3/2 → 2I9/2 and Yb3+: 2F5/2 → 2F7/2 transitions, the BaGd2(MoO4)4: 3 mol%Nd3+, 15 mol%Yb3+ sample displayed excellent thermal sensitivity (2.28–8.42 %K−1) and temperature resolution (0.1–0.22 K) at temperatures ranging from 298 K to 573 K, which were superior to those of many other reported luminescence materials. The present work might give a new input for developing near-infrared (NIR) luminescence materials with desirable temperature sensing performances.

High sensitivity temperature and gas pressure sensor based on PDMS sealed tapered hollow-core fiber

We use hollow core fiber (HCF) and single mode fiber (SMF) fusion splicing to form a sensor with a “SMF-HCF-SMF” structure. To improve the sensitivity of the sensor, the HCF is tapered and stretched to a waist diameter of 10 μm. Then, in order to further improve the sensitivity of the sensor to temperature and pressure, as well as the mechanical strength of the sensor, we coated a layer of polydimethylsiloxane (PDMS) thin film on the surface of the tapered HCF. When light propagates in the sensor, an anti-resonant reflection optical waveguide (ARROW) mechanism is formed. Due to the excellent thermal sensitivity and elasticity of PDMS, the transmission spectrum of the sensor will significantly drift due to changes in environmental temperature and gas pressure, achieving temperature and pressure measurement. The experimental results show that the maximum temperature and gas pressure sensitivity of the sensor reach −3.2321 nm/℃ and −22.80 nm/MPa, respectively. In addition, the sensor also has good repeatability and stability, as well as short response time. It has certain application prospects in the field of high sensitivity temperature and gas pressure sensing measurement.

Using high entropy configuration strategy to design high-temperature thermosensitive ceramics with superior thermal stability and a wide temperature range

Entropy plays a crucial role in designing new functional materials or enhancing material performance. The design of high entropy ceramics (HECs) introduces a larger composition space, thus the understanding of the correlation between the composition, entropy effect, and the performance of HECs is becoming increasingly important. In this work, to pursue superior properties, a series of CeNbO4-based solid solution ceramics with a maximum of 9 species cations in a single sublattice were synthesized by using high entropy configuration strategy. The interaction of composition, size disorder, and configurational entropy on the properties of HECs was emphasized. The potential conflict between high resistivity and low material constant of thermosensitive ceramics was overcome and thus achieving excellent thermal sensitivity properties having an extremely wide temperature range from room temperature to 1623 K and long-term high-temperature stability. This will bring innovative prospects for the design and application of high-temperature functional ceramics.

Wearable Temperature Sensors Based on Reduced Graphene Oxide Films.

With the development of medical technology and increasing demands of healthcare monitoring, wearable temperature sensors have gained widespread attention because of their portability, flexibility, and capability of conducting real-time and continuous signal detection. To achieve excellent thermal sensitivity, high linearity, and a fast response time, the materials of sensors should be chosen carefully. Thus, reduced graphene oxide (rGO) has become one of the most popular materials for temperature sensors due to its exceptional thermal conductivity and sensitive resistance changes in response to different temperatures. Moreover, by using the corresponding preparation methods, rGO can be easily combined with various substrates, which has led to it being extensively applied in the wearable field. This paper reviews the state-of-the-art advances in wearable temperature sensors based on rGO films and summarizes their sensing mechanisms, structure designs, functional material additions, manufacturing processes, and performances. Finally, the possible challenges and prospects of rGO-based wearable temperature sensors are briefly discussed.

Magneto-Induced Hyperthermia and Temperature Detection in Single Iron Oxide Core-Silica/Tb3+/Eu3+(Acac) Shell Nano-Objects.

Multifunctional nano-objects containing a magnetic heater and a temperature emissive sensor in the same nanoparticle have recently emerged as promising tools towards personalized nanomedicine permitting hyperthermia-assisted treatment under local temperature control. However, a fine control of nano-systems’ morphology permitting the synthesis of a single magnetic core with controlled position of the sensor presents a main challenge. We report here the design of new iron oxide core–silica shell nano-objects containing luminescent Tb3+/Eu3+-(acetylacetonate) moieties covalently anchored to the silica surface, which act as a promising heater/thermometer system. They present a single magnetic core and a controlled thickness of the silica shell, permitting a uniform spatial distribution of the emissive nanothermometer relative to the heat source. These nanoparticles exhibit the Tb3+ and Eu3+ characteristic emissions and suitable magnetic properties that make them efficient as a nanoheater with a Ln3+-based emissive self-referencing temperature sensor covalently coupled to it. Heating capacity under an alternating current magnetic field was demonstrated by thermal imaging. This system offers a new strategy permitting a rapid heating of a solution under an applied magnetic field and a local self-referencing temperature sensing with excellent thermal sensitivity (1.64%·K−1 (at 40 °C)) in the range 25–70 °C, good photostability, and reproducibility after several heating cycles.

Skin-Inspired Thermoreceptors-Based Electronic Skin for Biomimicking Thermal Pain Reflexes.

Electronic systems possessing skin‐like morphology and functionalities (electronic skins [e‐skins]) have attracted considerable attention in recent years to provide sensory or haptic feedback in growing areas such as robotics, prosthetics, and interactive systems. However, the main focus thus far has been on the distributed pressure or force sensors. Herein a thermoreceptive e‐skin with biological systems like functionality is presented. The soft, distributed, and highly sensitive miniaturized (≈700 µm2) artificial thermoreceptors (ATRs) in the e‐skin are developed using an innovative fabrication route that involves dielectrophoretic assembly of oriented vanadium pentoxide nanowires at defined locations and high‐resolution electrohydrodynamic printing. Inspired from the skin morphology, the ATRs are embedded in a thermally insulating soft nanosilica/epoxy polymeric layer and yet they exhibit excellent thermal sensitivity (−1.1 ± 0.3% °C−1), fast response (≈1s), exceptional stability (negligible hysteresis for >5 h operation), and mechanical durability (up to 10 000 bending and twisting loading cycles). Finally, the developed e‐skin is integrated on the fingertip of a robotic hand and a biological system like reflex is demonstrated in response to temperature stimuli via localized learning at the hardware level.

Determination of near-infrared downconversion emission of Yb3+ and optical temperature sensing performances in Nd3+-sensitized SrF2 nanocrystals

In this work, a series of Nd3+ and Yb3+ codoped SrF2 nanocrystals (NCs) were synthesized by the hydrothermal method. The TEM results show that the average size of these NCs is approximately ∼50 nm. The structure of SrF2 NCs and its optical properties of near-infrared (NIR) downconversion luminescence (DCL) are systematically characterized. Under the excitation of 808 nm laser, intense NIR DCL centered at 976 nm from Yb3+ ions is experimentally determined. The mechanism of the DCL is further interpreted based on the efficient energy-transfer (ET) processes from Nd3+ to Yb3+. In addition, utilizing the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors of SrF2:Nd3+/Yb3+ (15/4 mol%) are also investigated through the heterogeneously coupled states between Nd3+ (4F3/2 → 4I11/2) and Yb3+ (2F5/2 → 2I7/2) in a temperature range of 298–573 K. The results confirm that the maximum thermal sensitivity is up to 0.00346 K−1 at 473K. The excellent thermal sensitivity of these NCs, particularly the DCL located at the NIR region, have the potential for biological applications and temperature measurement at the nanoscale.

Multifunctional optical thermometry based on the transition metal ions doped down-conversion Gd2ZnTiO6: Bi3+, Mn4+ phosphors

Nowadays, how to improve the accuracy of the temperature sensors has become a common concern of researchers. For this purpose, dual-emitting phosphors have been proposed as a novel optical thermometer because the two discriminate emission centers can avoid the error caused by spectral overlap. Herein, a new ratio-metric luminescent thermometer Gd2ZnTiO6(GZTO):Bi3+, Mn4+ is designed, which exhibits both red and blue luminescence under 375 nm excitation. Based on the different thermal sensitivity of Mn4+ and Bi3+ ions and the energy transfer from Bi3+ to Mn4+ ions, the luminescent thermometer reveals excellent thermal sensitivity (Sr = 2.4% K−1, Sa = 16.8%K−1) and a wide temperature measurement range (313–473 K). Both of them are superior to the most reported materials. In addition, the luminescence intensity of two ions matches the light absorption bands of photosynthetic pigment well, which indicates that GZTO: Bi3+, Mn4+ phosphors also have a great prospect as a plant growth lamp.

Flame-made Y2O3:Yb3+/Er3+ upconversion nanoparticles: Mass production synthesis, multicolor tuning and thermal sensing studies

Developing a rapid and continuous synthesis method for scalable production of upconversion nanoparticles (UCNPs) plays an important role in the applications of advanced color display, high-resolution biomedical imaging and precise optical thermometry. Here, for the first time, we report the multicolor tunable upconversion luminescence (UCL) in Y2O3:Yb3+/Er3+ (x/1 mol%) UCNPs with the average size of ∼14 nm, which were successfully fabricated by liquid-fed flame aerosol synthesis with a high production rate of ∼40 g h−1. Under the excitation of 980 nm continuous-wave (CW) laser, the UCL color can be efficiently modulated from green to red and the red-to-green (R/G) UCL intensity ratio is enhanced dramatically as the doping concentration of Yb3+ ions increases from 1 to 15 mol%. The UCL color manipulation can be ascribed to the cross-relaxation (CR) and the energy back transfer (EBT) processes between Yb3+ and Er3+ ions, and it was proved by investigating the dependence of UCL on the pump power and the decay lifetimes of 4S3/2 and 4F9/2 states. Moreover, the coefficients of CR and EBT processes were also calculated by a rate equation model, and the results suggest that they are efficient in Y2O3 host. In addition, the optical thermal sensing performance was also evaluated by analyzing fluorescence intensity ratio (FIR) of the thermally coupled levels (2H11/2, 4S3/2) of Er3+ ions in Y2O3:Yb3+/Er3+ (1/1 mol%) UCNPs, achieving an excellent thermal sensitivity of 0.0196 K−1 at 543 K.

Super-ductile, injectable, fast self-healing collagen-based hydrogels with multi-responsive and accelerated wound-repair properties

Collagen-based hydrogels have been regarded as one of the most popular biomaterials for applications in biomedical engineering as scaffolds, cell or drug carriers and medical implants. Despite numerous studies on collagen-based hydrogels, their applications are still extremely limited due to lack of multi-functionalities. Herein, we present a facile method to prepare a multifunctional, extremely soft collagen-based hydrogel via the introduction of collagen (COL), guar gum (GG), poly(N-isopropylacrylamide) (PNIPAM), graphene oxide (GO) and borax through the formation of both reversible and permanent networks. The resultant hydrogels (COL–GG–PNIPAMs) exhibited desirable properties, including processability, injectability and remoldability. Remarkably, the COL–GG–PNIPAMs stretched manually up to 50 times their initial length before rupturing (from 2 to 100 cm), indicating their super-ductile deformation; when cut, the hydrogels self-healed within a short time period (less than 3 min) without any external stimuli. In addition, the COL–GG–PNIPAMs showed excellent thermal sensitivity and NIR-responsive properties. The potential application of ionic conductive COL–GG–PNIPAMs for strain sensing was also tested by monitoring real-time large-scale movements of the human body or facial micro-expressions. Moreover, the COL–GG–PNIPAMs exhibited a healing ratio of 81.0% for mouse skin wounds, which was higher than that of the blank group (63.6%), demonstrating an enhanced skin wound repair effect. These prominent features of COL-GG-PNIPAMs will broaden versatile collagen-based hydrogels for a variety of applications.

Skin-inspired cellulose conductive hydrogels with integrated self-healing, strain, and thermal sensitive performance

In this study, a versatile cellulose conductive hydrogels with outstanding mechanical properties, rapid self-healing performance, and excellent thermal sensitivity were successfully fabricated. The tensile strength and toughness of the gels gradually increased to 249 kPa and 1.57 MJ/m3, respectively, and the healing efficiency of the hydrogels quickly reached 96.3% within 60 min. Importantly, the hydrogels exhibited a broad strain window (0–2066%) with a gauge factor ranging from 0.22 to 6.7, which could monitor of both obvious and subtle motion of the human body with high sensitivity and good repeatability. Moreover, the sensors also possessed good thermal sensitivity in the 0% and 400% state, and the response of the gel sensors increased from 8.3 to 87.9 when the temperature was increased from 35 to 85 °C. This study provides inspiration for the development of biocompatible and multifunctional cellulose-based wearable sensors with excellent mechanical, strain and temperature sensing and self-healing properties.

Double NIR laser stimulation and enhancing the thermal sensitivity of Er3+/Tm3+/Nd3+ doped multilayer core–shell nanoparticles

Non-contact thermal sensors are important devices to study cellular processes and monitor temperature in vivo. Herein, a novel highly sensitive nanothermometer based on NaYF4:Yb,Er@ NaYF4@NaYF4:Yb,Tm@ NaYF4:Nd (denoted as Er@Y@Tm@Nd) was prepared by a facile solvothermal method. When excited by the near-infrared (NIR) light of 808 and 980 nm, the as-prepared Er@Y@Tm@Nd nanoparticles could emit both blue and green light, respectively, since the lanthanide cations responsible for these emissions are gathered inside this nanostructure. The green and blue light intensity ratio exhibits obvious temperature dependence in the range of the physiological temperature. Additionally, the fluorescence intensity of Er3+ and Tm3+ are also greatly enhanced due to the multilayer structure that implies avoiding the Er3+ and Tm3+ energy cross-relaxation by introduction of a NaYF4 wall between them. The as-prepared core–shell–shell–shell structure with Er3+ and Tm3+ in different layers improves dozens of times of the thermal sensitivity based on the non-thermal coupling levels of the probe: the maximum values for the sensitivity are 2.95% K−1 (IEr-521/ITm-450) and 6.30% K−1 (ITm-474/IEr-541) when excited by 980 and 808 nm laser sources, respectively. These values are well above those previously reported (<0.7% K−1), indicating that the prepared nanostructures are temperature sensors with excellent thermal sensitivity and sensitive to NIR wavelength excitation that makes them highly preferred for thermal detection.

Switchable heat transfer mechanisms of nucleation and convection by wettability match of evaporator and condenser for heat pipes: Nano-structured surface effect

A novel strategy was proposed for the improvement of vapor chamber heat pipe (HP) performance. The mastoid process array, wettability control of heat pipe and control of liquid charged into heat pipe are comprehensively used to manage the phase distribution. Thus, the two dominant heat transfer mechanisms of nucleation and convection can be switched. The objective of this strategy is to maintain nucleation mechanism but suppress convection mechanism. Holding the nucleation mechanism, our newly developed heat pipe behaves excellent thermal sensitivity with respect to heating loads. Our idea was thoroughly verified by experiments, in which three HP samples were fabricated and tested: #1 equal wettability sample, #2 moderate wettability difference sample and #3 opposite wettability sample. The wettability difference was generated with nano-structured surface. The #1 sample shows convection mechanism with heat transfer coefficients (HTCs) not changed versus heat fluxes, due to evaporator porous wick occupied by larger vapor content and liquid filmwise condensation on condenser surface. The super-hydrophilic evaporator and super-hydrophobic condenser (#3 sample) shows nucleation mechanism with HTCs significantly increased with increases in heat fluxes, due to large driving force to flood evaporator porous wick by water and expose condenser by vapor. Surprisingly, opposite wettability match HP had overall thermal resistances of only 1/3 to those of equal wettability HP. The comprehensive use of mastoid process array and controls of wettability and water amount charged into HP lowers heater temperatures by 30–40°C at high heat fluxes such as ~100W/cm2 on a large heater area of 1.4cm2, paving a new road for heat pipe performance improvement.

Supramolecular polymer micelles as universal tools for constructing high-performance fluorescent nanoparticles

This study is the first attempt to encapsulate fluorescent rhodamine 6G (R6G) into supramolecular micelles as a means of manipulating the fluorescence color and quantum efficiency of R6G, and provides a quick and simple route towards the fabrication of high-efficiency fluorescent nanoparticles for next-generation lighting devices and biomedical image applications. We demonstrate that these R6G-loaded micelles exhibit a uniform size distribution, tunable R6G loading capacity and a rapid R6G release rate, in combination with excellent thermal sensitivity due to dissociation of the dynamic hydrogen bonds at environmental temperatures above the lower critical solution temperature. Importantly, R6G-loaded micelles act as an effective chromophore to greatly improve the fluorescence-color stability of R6G in aqueous solution and provide a maximum quantum yield of 0.75, which is more than two times higher than that of the equivalent concentration of free R6G; these features are highly desirable yet extremely rare in conventional polymer carriers and low-molecular-weight surfactant systems.

Intracellular Thermometry by Using Fluorescent Gold Nanoclusters

The "gold standard" for nanothermometry: The application of ultrasmall, near-IR-emitting fluorescent gold nanoclusters (AuNCs) for temperature sensing has been explored. AuNC-based fluorescent nanothermometry features excellent thermal sensitivity and simultaneous temperature sensing and imaging in HeLa cells.

Study on thermal sensitivity of a VOx/SiO 2/PS/Si multi-layer structure

Vanadium oxide (VOx) thin films are considered as one of the optimal sensitive materials used in micro-thermal detectors for its excellent thermal sensitivity. Porous Si (PS) as thermal insulator used in MEMS is fast developed. In this paper, a VOx/ SiO 2/ PS/Si multi-layer structure with well thermal sensitivity is presented. Excellent thermal insulation of PS and high thermal sensitivity of VOx thin film make the structure to attain maximal thermal response signal which is the input signal of microdetector readout circuit. In the structure PS is formed in substrate Si by electrochemical etching as a thermal insulator. VOx thin film is deposited by direct current reactive magnetron sputtering as a thermal detector. SiO 2 by PECVD acts as an electro-insulator between PS and VOx. Experiments prove the multi-layer structure has excellent thermal sensitivity and its thermal response is much better than a similar structure without PS under the condition of 20 μW input power.