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This study analyzed the optical and laser spot acquisition capabilities of a newly developed dual-wavelength-band camera. The camera performance was evaluated using a 3.0 m × 1.8 m Styrofoam target and a 70-mJ laser target designator; mid-infrared images were acquired based on the target distance, and a laser beam was irradiated onto the target to detect laser spots. The dual-wavelength-band camera demonstrated target recognition and spot detection ranges of 3 and 2 km, respectively. The results demonstrated that laser spot images could be obtained with a laser reception power of 65 µW or higher.

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The response of a DPbS3200 infrared detector irradiated by a nanosecond pulsed laser and CW laser has been investigated to study laser-induced interference. A laser interference experiment system was constructed to measure the time-varying response signal. A nanosecond pulsed laser and a CW laser of 10 Hz were used, with a 1064 nm wavelength and a millimeter-scale irradiation spot diameter. Firstly, the characteristics of transient interference signals induced by pulsed lasers were analyzed. Then, the characteristics of response signal interference by both CW laser and pulsed laser irradiation were further investigated. The results showed that the pulsed laser only produced transient interference. However, the CW laser led to a significant amplitude reduction of the response signal, which could continuously interfere in the operating time. For transient interferences, the amplitude of the interference signal increased linearly with the laser fluence. The relation between the pulse repetition rate of the incident laser and the operating frequency of the detector determined the numbers of transient interference signals in one response period; for the interference induced by both the CW laser and pulsed laser, CW laser interference played a leading role when CW laser power density increased to 4.1 W/cm2 or more. As the CW laser fluence reached 6.1 W/cm2, the PbS infrared detector was no longer able to detect any signal, which caused temporary blindness. In the end, a probit model was used to determine the interference threshold.

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This paper introduces a cost-effective, high-performance approach to achieving wafer level vacuum packaging (WLVP) for MEMS-based uncooled infrared sensors. Reliable and hermetic packages for MEMS devices are achieved using a cap wafer that is formed using two silicon wafers, where one wafer has precise grating/moth-eye structures on both sides of a double-sided polished wafer for improved transmission of over 80% in the long-wave infrared (LWIR) wavelength region without the need for an AR coating, while the other wafer is used to form a cavity. The two wafers are bonded using Au-In transient liquid phase (TLP) bonding at low temperature to form the cap wafer, which is then bondelectrical and Electronics d to the sensor wafer using glass frit bonding at high temperature to activate the getter inside the cavity region. The bond quality is assessed using three methods, including He-leak tests, cap deflection, and Pirani vacuum gauges. Hermeticity is confirmed through He-leak tests according to MIL-STD 883, yielding values as low as 0.1 × 10-9 atm·cc/s. The average shear strength is measured as 23.38 MPa. The package pressure varies from 133-533 Pa without the getter usage to as low as 0.13 Pa with the getter usage.

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Passive infrared (IR) systems enable rapid detection of chemical vapors but are limited by size, weight, cost, and power. Previously, the authors reported a novel passive sensor that utilizes multiple IR filter/detector combinations to discriminate between different chemical vapors based on their unique IR absorption spectra in the same manner the human eye uses to generate colors. This approach enables a very small, compact, and low-power sensor system with the capability to discriminate between chemical vapors of interest and background chemicals. All previous work showed the capability of this sensor system in discriminating chemical vapors against a hot blackbody in a laboratory environment. Now the authors demonstrate the ability of this sensor system to discriminate between the chemical vapor agent simulant dimethyl methylphosphonate and ethanol against the cold sky in an outdoor environment.

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Low-noise, high-performance long-wave infrared detectors play a crucial role in diverse applications, including in the industrial, security, and medical fields. However, the current performance of long-wave detectors is constrained by the noise associated with narrow bandgaps. Therefore, exploring novel heterostructures for long-wavelength infrared detection is advantageous for the development of compact and high-performance infrared sensing. In this investigation, we present a MoS2/type II superlattice mixed-dimensional van der Waals barrier long-wave infrared detector (Mixed-vdWH). Through the design of the valence band barrier, substantial suppression of device dark noise is achieved, resulting in 2 orders of magnitude reduction in dark current. The device exhibits outstanding performance, with D* reaching 4 × 1010 Jones. This integration approach synergizes the distinctive properties of two-dimensional layered materials (2DLM) with the well-established processing techniques of traditional three-dimensional semiconductor materials, offering a compelling avenue for the large-scale integration of 2DLM.

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Artificial skin, endowed with the capability to perceive thermal stimuli without physical contact, will bring innovative interactive experiences into smart robotics and augmented reality. The implementation of touchless thermosensation, responding to both hot and cold stimuli, relies on the construction of a flexible infrared detector operating in the long-wavelength infrared range to capture the spontaneous thermal radiation. This imposes rigorous requirements on the photodetection performance and mechanical flexibility of the detector. Herein, a flexible and wearable infrared detector is presented, on basis of the photothermoelectric coupling of the tellurium-based thermoelectric multilayer film and the infrared-absorbing polyimide substrate. By suppressing the optical reflection loss and aligning the destructive interference position with the absorption peak of polyimide, the fabricated thermopile detector exhibits high sensitivity to the thermal radiation over a broad source temperature range from -50 to 110 °C, even capable of resolving 0.05 °C temperature change. Spatially resolved radiation distribution sensing is also achieved by constructing an integrated thermopile array. Furthermore, an established temperature prewarning system is demonstrated for soft robotic gripper, enabling the identification of noxious thermal stimuli in a contactless manner. A feasible strategy is offered here to integrate the infrared detection technique into the sensory modality of electronic skin.

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As commodity plastics, polyolefins are in high demand and used in innumerable applications. An important reason for their success-story is their high versatility in terms of applications. The application range of polyolefins was significantly extended through the development of functionalization. A common functionalization for improving the compatibility of polyolefins with more polar polymers and surfaces is grafting with maleic anhydride. While maleic anhydride-grafted polyolefins have found widespread application, methods for their characterization remain rudimentary compared to the developments seen in the structural characterization of polyolefins in general. Herein, we propose two new approaches for determining the degree of functionalization as a function of the molar mass of maleic anhydride grafted polyolefins. On the one hand, the latest generation bandpass filter-based IR detectors are shown to be sensitive to the carbonyl moiety of MAH. After optimization of analysis conditions, the relation between MAH content and molar mass could be unraveled in an easily applicable approach suitable for routine analysis. On the other hand, the high reactivity of MAH was leveraged in a tagging approach. By imidization with a UV chromophore, MAH distribution can be assessed by HT-GPC-UV with significantly higher sensitivity compared to HT-GPC-IR.

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Objective: : As dopamine is closely linked to locomotor activities, animal studies on locomotor activities using dopaminergic agents were widely done. However, most of animal studies were performed for a short period that there is a lack of longitudinal study on the effects of dopaminergic agents on locomotor activities. This study aimed to examine the longterm effect of a dopamine D2, D3 agonist quinpirole on locomotor activities in mice using a home-cage monitoring system. Methods: : The locomotor activities of Institute Cancer Research mice were measured by infrared motion detectors in home-cages under the 12-hour dark and 12-hour light condition for three days after the quinpirole injection. Quinpirole was injected at a concentration of 0.5 mg/kg intraperitoneally in the beginning of the dark phase. The locomotor activities before and after the quinpirole administration were compared by the Wilcoxon signed-rank test and one-way repeated measures ANOVA. Results: : After the quinpirole administration, the 24-hour total locomotor activity did not change (p = 0.169), but activities were significantly increased in the 12-hour dark phase sum (p = 0.013) and decreased in the 12-hour light phase sum (p = 0.009). Significant increases in the activities were observed in the dark-light difference (p = 0.005) and dark-light ratio (p = 0.005) as well. Conclusion: : This study suggests that quinpirole injection entrains the circadian rest-activity rhythm of locomotor activities. Therefore, quinpirole can be a drug that mediates locomotor activity as a dopamine agonist as well as a modulator of the circadian rhythms.

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We demonstrate an extended short-wave infrared (e-SWIR) photodetector composed of an InAs/GaAs(111)A heterostructure with interface misfit dislocations. The layer structure of the photodetector consists simply of an n-InAs optical absorption layer directly grown with a thin undoped-GaAs spacer layer on n-GaAs by molecular beam epitaxy. The lattice mismatch was abruptly relaxed by forming a misfit dislocation network at the initial stage of the InAs growth. We found high-density threading dislocations (1.5 × 109 cm-2) in the InAs layer. The current-voltage characteristics of the photodetector at 77 K had a very low dark current density (<1 × 10-9 A cm-2) at a positive applied voltage (electrons flow from n-GaAs to n-InAs) of up to ∼+1 V. Simulation of the band structure revealed that the direct connection of GaAs and InAs and the formation of interfacial states by the misfit dislocations play significant positive roles in suppressing dark current. Under illumination with e-SWIR light at 77 K, a clear photocurrent signal was observed with a 2.6 µm cutoff wavelength, which is consistent with the bandgap of InAs. We also demonstrated e-SWIR detection at room temperature with a 3.2 µm cutoff wavelength. The maximum detectivity at 294 K exceeds 2 × 108 cm Hz0.5 W-1 for the detection of e-SWIR light at 2 µm.

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The rapid expansion of the applications of infrared (IR) sensing in the commercial market has driven the need to develop new materials and detector designs for enhanced performance. In this work, we describe the design of a microbolometer that uses two cavities to suspend two layers (sensing and absorber). Here, we implemented the finite element method (FEM) from COMSOL Multiphysics to design the microbolometer. We varied the layout, thickness, and dimensions (width and length) of different layers one at a time to study the heat transfer effect for obtaining the maximum figure of merit. This work reports the design, simulation, and performance analysis of the figure of merit of a microbolometer that uses GexSiySnzOr thin films as the sensing layer. From our design, we obtained an effective thermal conductance of 1.0135×10-7 W/K, a time constant of 11 ms, responsivity of 5.040×105 V/W, and detectivity of 9.357×107 cm-Hz1/2/W considering a 2 µA bias current.

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The assorted utilization of infrared detectors induces the demand for more comprehensive and high-performance electronic devices that work at room temperature. The intricacy of the fabrication process with bulk material limits the exploration in this field. However, two-dimensional (2D) materials with a narrow band gap opening aid in infrared (IR) detection relatively, but the photodetection range is narrowed due to the inherent band gap. In this study, we report an unprecedented attempt at the coordinated use of both 2D heterostructure (InSe/WSe2) and the dielectric polymer (poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE)) for both visible and IR photodetection in a single device. The remnant polarization due to the ferroelectric effect of the polymer dielectric enhances the photocarrier separation in the visible range, resulting in high photoresponsivity. On the other hand, the pyroelectric effect of the polymer dielectric causes a change in the device current due to the increased temperature induced by the localized heating effect of the IR irradiation, which results in the change of ferroelectric polarization and induces the redistribution of charge carriers. In turn, it changes the built-in electric field, the depletion width, and the band alignment across the p-n heterojunction interface. Consequently, the charge carrier separation and the photosensitivity are therefore enhanced. Through the coupling between pyroelectricity and built-in electric field across the heterojunction, the specific detectivity for the photon energy below the band gap of the constituent 2D materials can reach up to 1011 Jones, which is better than all reported pyroelectric IR detectors. The proposed approach combining the ferroelectric and pyroelectric effects of the dielectric as well as exceptional properties of the 2D heterostructures can spark the design of advanced and not-yet realized optoelectronic devices.

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A novel Epitaxial Cadmium Selenide (CdSe) on Lead Selenide (PbSe) type-II heterojunction photovoltaic detector has been demonstrated by Molecular Beam Epitaxy (MBE) growth of n-type CdSe on p-type PbSe single crystalline film. The use of Reflection High-Energy Electron Diffraction (RHEED) during the nucleation and growth of CdSe indicates high-quality single-phase cubic CdSe. This is a first-time demonstration of single crystalline and single phase CdSe growth on single crystalline PbSe, to the best of our knowledge. The current-voltage characteristic indicates a p-n junction diode with a rectifying factor over 50 at room temperature. The detector structure is characterized by radiometric measurement. A 30 µm × 30 µm pixel achieved a peak responsivity of 0.06 A/W and a specific detectivity (D*) of 6.5 × 108 Jones under a zero bias photovoltaic operation. With decreasing temperature, the optical signal increased by almost an order of magnitude as it approached 230 K (with thermoelectric cooling) while maintaining a similar level of noise, achieving a responsivity of 0.441 A/W and a D* of 4.4 × 109 Jones at 230 K.

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Quantum dots have found significant applications in photoelectric detectors due to their unique electronic and optical properties, such as tunable bandgap. Recently, colloidal quantum dots (CQDs) have attracted much interest because of the ease of controlling the dot size and low production cost. In this paper, a high-performance ZnO/PbS heterojunction photodetector was fabricated by spin-coating PbS CQDs onto the surface of a hydrothermally grown vertical array of ZnO nanowires (NWs) on an indium tin oxide (ITO) substrate. Under 940 nm near-infrared light illumination, the device demonstrated a responsivity and detectivity of ~3.9 × 104 A/W and ~9.4 × 1013 Jones, respectively. The excellent performances and low cost of this nanocomposite-based photodetector show that it has the potential for widespread applications ranging from medical diagnosis to environmental monitoring.

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Carbon nanotube (CNT) is an ideal candidate material for shortwave infrared (SWIR) detectors due to its large band gap tunability, strong infrared light absorption, and high mobility. Furthermore, the photodetectors based on CNT can be prepared on any substrate using a low-temperature process, which is conducive to three-dimensional (3D) integration. However, owing to the absorption limitation (<2%) of a single-layer network CNT film with low density, the photodetectors of CNT film show low photocurrent responsivity and detectivity. In this paper, we optimize the thickness of the high-purity semiconducting network CNT films to increase the photocurrent responsivity of the photodetectors. When the thickness of network CNT film is about 5 nm, the responsivity of the zero-bias voltage can reach 32 mA/W at 1800 nm wavelength. Then, using stacked CNT films and contact electrode design, the photodetectors exhibit a maximum responsivity of 120 mA/W at 1800 nm wavelength. The photodetectors with stacked CNT films and local n-type channel doping demonstrated a wide response spectral range of 1200-2100 nm, a peak detectivity of 3.94 × 109 Jones at room temperature, and a linear dynamic range over 118 dB. Moreover, the peak detectivity is over 2.27 × 1011 Jones when the temperature is 180 K. Our work demonstrates the potential of the CNT film for future SWIR imaging at a low cost.

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Microbolometers based on the CMOS process has the important advantage of being automatically merged with circuits in the fabrication of larger arrays, but they typically suffer from low detectivity due to the difficulty in realizing high-sensitivity thermistors in the CMOS process. In this paper, two resistive microbolometers based on polysilicon and metal Al thermistors, respectively, are designed and fabricated by the standard CMOS process. Experimental results show that the detectivity of the two resistive microbolometers can reach a maximum of 1.78 ´ 109 cmHz1/2/W at 25 µA and a maximum of 6.2 ´ 108 cmHz1/2/W at 267 µA. The polysilicon microbolometer exhibits better detectivity at lower bias current due to its lower effective thermal conductivity and larger resistance. Even though the thermal time constant of the polysilicon thermistor is three times slower than that of the metal Al thermistor, the former is more suitable for designing a thermal imaging system with sensitive and low power consumption.

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Highly sensitive short-wave infrared (SWIR) detectors, compatible with the silicon-based complementary metal oxide semiconductor (CMOS) process, are regarded as the key enabling components in the miniaturized system for weak signal detection. To date, the high photogain devices are greatly limited by a large bias voltage, low-temperature refrigeration, narrow response band, and complex fabrication processes. Here, we demonstrate high photogain detectors working in the SWIR region at room temperature, which use graphene for charge transport and Te-hyperdoped silicon (Te-Si) for infrared absorption. The prolonged lifetime of carriers, combined with the built-in potential generated at the interface between the graphene and the Te-Si, leads to an ultrahigh photogain of 109 at room temperature (300 K) for 1.55 µm light. The gain can be improved to 1012, accompanied by a noise equivalent power (NEP) of 0.08 pW Hz-1/2 at 80 K. Moreover, the proposed device exhibits a NEP of 4.36 pW Hz-1/2 at 300 K at the wavelength of 2.7 µm, which is exceeding the working region of InGaAs detectors. This research shows that graphene can be used as an efficient platform for silicon-based SWIR detection and provides a strategy for the low-power, uncooled, high-gain infrared detectors compatible with the CMOS process.

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GaN-based quantum well infrared detectors can make up for the weakness of GaAs-based quantum well infrared detectors for short-wave infrared detection. In this work, GaN/AlN (1.8 nm/1.8 nm) multi-quantum wells have been epitaxially grown on sapphire substrate using MBE technology. Meanwhile, based on this device structure, the band positions and carrier distributions of a single quantum well are also calculated. At room temperature, the optical response of the device is 58.6 µA/W with a bias voltage of 0.5 V, and the linearity between the optical response and the laser power is R2 = 0.99931. This excellent detection performance can promote the research progress of GaN-based quantum well infrared detectors in the short-wave infrared field.

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Polyvinylidene fluoride (PVDF) is a very promising material for fabricating flexible infrared sensors due to its ferroelectricity as well as excellent flexibility and low fabrication cost. This work focuses on improving PVDF's pyroelectric performance by creating microstructures in the film. Simulation results suggest that the pyroelectric response of PVDF film can be improved if micro groove, square-pit or sinusoidal patterns are created on the film surface, with the grooved film showing the best pyroelectric performance. Suggested by the simulation results, flexible PVDF samples with groove structure are prepared by casting the precursor solution on the mold with designed patterns. Measurement results demonstrate that the optimal microstructured PVDF film can improve its pyroelectric performance by as high as 146%, which is in good agreement with the simulations. This work provides an innovative way of achieving flexible infrared sensor devices with promoted performance based on pyroelectric polymers.

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The feature of a space-based infrared signal is that the intensity of clutter is much stronger than that of an aerial target. Such a feature poses a great challenge to aerial target detection since the existing infrared target detection methods are prone to enhance clutter but ignore the real target, which results in missed detection and false alarms. To tackle the challenge, we propose a concise method based on local spatial-temporal matching (LSM). Specifically, LSM mainly consists of local normalization, local direction matching, spatial-temporal joint model, and inverse matching. Local normalization aims to enhance the target to the same strength as the clutter, so that the weak target will not be ignored. After normalization, a direction-matching step is applied to estimate the moving direction of the background between the basic frame and referenced frame. Then the spatial-temporal joint model is constructed to enhance the target and suppress strong clutter. Similarly, inverse matching is conducted to further enhance the target. Finally, a salience map is obtained, on which the aerial target is extracted by the adaptive threshold segmentation. Experiments conducted on four space-based infrared datasets indicate that LSM handles the above challenge and outperforms seven state-of-the-art methods in space-based infrared aerial target detection.

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In this paper, we design and optimize a low-cost, closed-film structure of a microelectromechanical systems (MEMS) thermopile infrared detector. By optimizing the circular arrangement of thermocouple strips and the thermal isolation design of the cold end to pursue a higher temperature difference, in addition to eliminating the absorption region, silicon nitride is deposited on the whole device surface as a passivated absorption layer. This reduces the cost while maintaining the voltage response and is suitable for mass production. The optimized detector had a 22.6% improvement in the response rate to 34.2 V/W, a detection rate of 1.02 × 108 cm·Hz1/2/W, and a response time of 26.9 ms. The design optimization of this detector provides a reference for further development of IR detectors.