Short-wave Infrared Imaging Research Articles

Novel multi-spectral short-wave infrared imaging for assessment of human burn wound depth.

Burn depth determination is critical for patient care but is currently lacking accuracy. Recent animal studies showed that Short Wave Infrared (SWIR) imaging can distinguish between superficial and deep burns. This is a first human study correlating reflectance of multiple SWIR bands using a SWIR assessment tool (SWAT) with burn depth classifications by surgeons and histology. Burns and adjacent normal skin in 11 patients with thermal injuries were imaged with visual and narrow bands centred at 1200, 1650, 1940 and 2250 nm and biopsies were taken from select areas. Reflectance intensities for each band in 273 regions of interest (ROI) were divided by the normal skin reflectance and combined into three Reflectance Indices (RIs). In addition, burns in ROIs and biopsies were classified by five surgeons and three pathologists, respectively, as superficial partial, deep partial, or full thickness. Results show that for burn depth increase classified by the surgeons, reflectance increased at 1200 and 2250, decreased at 1940, and didn't change at 1650 nm. In contrast, all three RIs increase with burn depth and predict the deep and full depths ROIs representing operable regions (Area Under Curve >0.6507, p < 0.0001). Pathologists' classification matched surgeons' classification of burn category only in eight of 21 biopsies (38.1%), but reflectance at all bands and one RI for all deep partial and full thickness biopsies were larger than in non-biopsy normal and superficial partial thickness ROIs (p < 0.0118). In conclusion, multi-spectral imaging with a new SWAT is a promising approach for evaluation of burn wound depth.

Shortwave Infrared Imaging of a Quantum Dot-Based Magnetic Guidewire Toward Non-Fluoroscopic Peripheral Vascular Interventions.

Peripheral vascular interventions (PVIs) offer several benefits to patients with lower extremity arterial diseases, including reduced pain, simpler anesthesia, and shorter recovery time, compared to open surgery. However, to monitor the endovascular tools inside the body, PVIs are conducted under X-ray fluoroscopy, which poses serious long-term health risks to physicians and patients. Shortwave infrared (SWIR) imaging of quantum dots (QDs) has shown great potential in bioimaging due to the non-ionizing penetration of SWIR light through tissues. In this paper, a QD-based magnetic guidewire and its system is introduced that allows X-ray-free detection under SWIR imaging and precise steering via magnetic manipulation. The QD magnetic guidewire contains a flexible silicone tube encapsulating a QD polydimethylsiloxane (PDMS) composite, where HgCdSe/HgS/CdS/CdZnS/ZnS/SiO2 core/multi-shell QDs are dispersed in the PDMS matrix for SWIR imaging upon near-infrared excitation, as well as a permanent magnet for magnetic steering. The SWIR penetration of the QD magnetic guidewire is investigated within an artificial tissue model (1% Intralipid) and explore the potential for non-fluoroscopic PVIs within a vascular phantom model. The QD magnetic guidewire is biocompatible in its entirety, with excellent resistance to photobleaching and chemical alteration, which is a promising sign for its future clinical implementation.

Synergic Surface Modifications of PbS Quantum Dots by Sodium Acetate in Solid-State Ligand Exchange toward Short-Wave Infrared Photodetectors.

PbS quantum dots (QDs) are promising for short-wave infrared (SWIR) photodetection and imaging. Solid-state ligand exchange (SSLE) is a low-fabrication-threshold QD solid fabrication method. However, QD treatment by SSLE remains challenging in seeking refined surface passivation to achieve the desired device performance. This work investigates using NaAc in the ligand exchange process to enhance the film morphology and electronic coupling configuration of QD solids. By implementing various film and photodetector device characterization studies, we confirm that adding NaAc with a prominent adding ratio of 20 wt % NaAc with tetrabutylammonium iodide (TBAI) in the SSLE leads to an improved film morphology, reduced surface roughness, and decreased trap states in the QD solid films. Moreover, compared to the devices without NaAc treatment, those fabricated with NaAc-treated QD solids exhibit an enhanced performance, including lower dark current density (<100 nA/cm2), faster response speed, higher responsivity, detectivity, and external quantum efficiency (EQE reaching 25%). The discoveries can be insightful in developing efficient, low-cost, and low-fabrication-threshold QD SWIR detection and imager applications.

High SNR eSWIR Image Sensor Applied in Advanced Hyperspectral Imager Aboard China’s GaoFen-5 Satellite and ZY-1 Satellite

This paper presents an extended short-wave infrared (eSWIR) image sensor, a large format infrared focal plane array (IRFPA), applied in advanced hyperspectral imager (AHSI) aboard China’s three GaoFen-5 satellites and two more followed ZY-1 satellites. Hyperspectral imaging has been emerged as a very important application in Earth observation instruments, for the spectral detection provides the spectrum information of ground objects except for the spatial imaging of the objects. AHSI has a 60-km swath width and a 30-m spatial resolution, and has high signal-to-noise ratio (SNR) in spectrum of interest. Large format infrared focal plane arrays which are ordinarily used in staring infrared imaging have some special performance requirements when applied in hyperspectral imaging, such as higher quantum efficiency, lower dark current, lower noise and selectable current conversion gain to match the different radiation flux of different subdivided spectral bands. We developed a format of 2048×512 HgCdTe/Si IRFPA sensor (equivalent 2012×256 after pixel overlapping and binning) in which 2012 pixels meet the demands of 60km swath width and 256 pixels line meet the 200 spectral bands. The sensor has 8-level gains selectable by spectral bands, and array dark current densities on an order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , quantum efficiency exceeding 80%, and the operability of 99.5% at operating temperature of around 110K. The SNR of this FPA achieved 150 when illuminated under 5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> photons/pixel.

Touchless short-wave infrared imaging for dynamic rapid pupillometry and gaze estimation in closed eyes

BackgroundAssessments of gaze direction (eye movements), pupil size, and the pupillary light reflex (PLR) are critical for neurological examination and neuroscience research and constitute a powerful tool in diverse clinical settings ranging from critical care through endocrinology and drug addiction to cardiology and psychiatry. However, current bedside pupillometry is typically intermittent, qualitative, manual, and limited to open-eye cases, restricting its use in sleep medicine, anesthesia, and intensive care.MethodsWe combined short-wave infrared (SWIR, ~0.9-1.7μm) imaging with image processing algorithms to perform rapid (~30 ms) pupillometry and eye tracking behind closed eyelids. Forty-three healthy volunteers participated in two experiments with PLR evoked by visible light stimuli or directing eye movements towards screen targets. Imaging was performed simultaneously on one eye closed, and the other open eye serving as ground truth. Data analysis was performed with a custom approach quantifying changes in brightness around the pupil area or with a deep learning U-NET-based procedure.ResultsHere we show that analysis of SWIR imaging data can successfully measure stimulus-evoked PLR in closed-eye conditions, revealing PLR events in single trials and significant PLRs in nearly all individual subjects, as well as estimating gaze direction. The neural net-based analysis could successfully use closed-eye SWIR data to recreate estimates of open-eye images and assess pupil size.ConclusionsContinuous touchless monitoring of rapid dynamics in pupil size and gaze direction through closed eyes paves the way for developing devices with wide-ranging applications, fulfilling long-standing goals in clinical and research fields.

High‐Speed Short Infrared Detector Based on Vertical Gr/Se0.2Te0.8/GaAs Heterojunction

AbstractIn the domain of high‐performance short‐wave infrared (SWIR) photodetection and imaging, existing technologies predominantly utilize single‐crystal germanium and III‐V semiconductors. Despite their efficacy, these materials are encumbered by laborious synthesis and complex fabrication demands. In this study, the synthesis of large‐area, high‐crystallinity Se0.2Te0.8 thin films through a CMOS‐compatible vacuum thermal evaporation process is reported. A high‐speed, broad‐spectrum photodetector engineered with an innovative Gr/Se0.2Te0.8/GaAs vertical heterostructure is presented, which capitalizes on the augmented carrier mobility and employs graphene innovatively as both a carrier collection interface and an electrode. This configuration facilitates a remarkably swift response time of 800 ns/1 µs at the crucial 1310 nm wavelength for optical communications. Moreover, the fabrication of a 5 × 5 array device demonstrates substantial SWIR imaging capabilities at ambient conditions, marking a paradigm shift in uncooled infrared imaging and communication technologies. This work not only extends the boundaries of SWIR photodetector performance but also underscores the potential of novel material systems in high‐speed optical applications.

Multiplexed Shortwave Infrared Imaging Highlights Anatomical Structures in Mice.

Multiplexed fluorescence in vivo imaging remains challenging due to the attenuation and scattering of visible and traditional near infrared (NIR-I, 650-950 nm) wavelengths. Fluorescence imaging using shortwave infrared (SWIR, 1000-1700 nm, a.k.a. NIR-II) light enables deeper tissue penetration due to reduced tissue scattering as well as minimal background autofluorescence. SWIR-emitting semiconductor quantum dots (QDs) with tunable emission peaks and optical stability are powerful contrast agents, yet few imaging demonstrations exclusively use SWIR emission beyond two-color imaging schemes. In this study, we engineered three high quality lead sulfide/cadmium sulfide (PbS/CdS) core/shell QDs with distinct SWIR emission peaks ranging from 1100-1550 nm for simultaneous three-color imaging in mice. We first use the exceptional photostability of QDs to non-invasively track lymphatic drainage with longitudinal imaging, highlighting the detailed networks of lymphatic vessels with widefield imaging over a 2 hr period. We then perform multiplexed imaging with all three QDs to distinctly visualize the lymphatic system and spatially overlapping vasculature networks, including clearly distinguishing the liver and spleen. This work establishes optimized SWIR QDs for next generation multiplexed and longitudinal preclinical imaging, unlocking numerous opportunities for preclinical studies of disease progression, drug biodistribution, and cell trafficking dynamics in living organisms.

Design of A prototype 128 × 128 ROIC array for 2.6 μm-wavelength SWIR image sensor applications

This paper presents the development and evaluation of a 128 × 128 Readout Integrated Circuit (ROIC) prototype, engineered for Short-Wave Infrared (SWIR) imaging at a specific target wavelength of 2.6 μm. Employing silicon-level verification, this work undertook an exhaustive analysis of the ROIC's performance, identifying key areas for enhancement to improve SWIR imaging systems. Fabricated with 0.18-μm CMOS technology, the ROIC is tailored for integration with Indium Gallium Arsenide (InGaAs) Focal Plane Arrays (FPAs), facilitating high-resolution imaging. The prototype consumes 42.25 mW of power and achieves a frame rate of 390 frames per second. The fabricated chip show that the random noise level is 72.65 μVrms and Pixel-FPN is 21 LSBrms. This investigation lays a critical groundwork for future SWIR imaging advancements, providing valuable insights and methodologies to boost imaging performance in various applications.

Short Wave Infrared Imaging for Auroral Physics and Aeronomy Studies

Advances in solar-terrestrial physics are generally linked to the development of innovative new sensor technologies, affording us ever better sensitivity, higher resolution, and broader spectral response. Recent advances in low-noise InGaAs sensor technology have enabled the realization of low-light-level scientific imaging within the short-wave infrared (SWIR) region of the electromagnetic spectrum. This paper describes a new and highly sensitive ultra-wide angle imager that offers an expansion of auroral and airglow imaging capabilities into the SWIR spectral range of 900–1,700 nm. The imager has already proven successful in large-area remote sensing of mesospheric temperatures and in providing intensity maps showing the propagation and dissipation of atmospheric gravity waves and ripples. The addition of an automated filter wheel expands the range of applications of an already versatile SWIR detector. Several potential applications are proposed herein, with an emphasis on auroral science. The combined data from this type of instrument and other existing instrumentation holds a strong potential to further enhance our understanding of the geospace environment.

One-Dimensional Crystal-Structure Te-Se Alloy for Flexible Shortwave Infrared Photodetector and Imaging.

Flexible shortwave infrared detectors play a crucial role in wearable devices, bioimaging, automatic control, etc. Commercial shortwave infrared detectors face challenges in achieving flexibility due to the high fabrication temperature and rigid material properties. Herein, we develop a high-performance flexible Te0.7Se0.3 photodetector, resulting from the unique 1D crystal structure and small elastic modulus of Te-Se alloying. The flexible photodetector exhibits a broad-spectrum response ranging from 365 to 1650 nm, a fast response time of 6 μs, a broad linear dynamic range of 76 dB, and a specific detectivity of 4.8 × 1010 Jones at room temperature. The responsivity of the flexible detector remains at 93% of its initial value after bending with a small curvature of 3 mm. Based on the optimized flexible detector, we demonstrate its application in shortwave infrared imaging. These results showcase the great potential of Te0.7Se0.3 photodetectors for flexible electronics.

Abstract 4178: Non-invasive shortwave infrared imaging of cytotoxic T lymphocyte infiltration for monitoring responses to combination immunotherapy and chemotherapy

Abstract Although triple-negative breast cancer (TNBC) can be treated with anti-PD-1 checkpoint immunotherapy in combination with chemotherapy, there remains a challenge in effectively monitoring therapeutic responses. Current non-invasive clinical imaging tools to evaluate response to treatment are reliant upon measurements of tumor volume and may fail to distinguish true progression from increased immune cell infiltration. Invasive biopsy sampling and immunohistochemistry (IHC) can elucidate changes in the immune landscape of treated tumors, but these methods are not conducive to providing real-time information. This study presents shortwave infrared (SWIR) imaging as a potential tool to detect treatment-induced cytotoxic T lymphocyte (CTL) infiltration non-invasively and in real time using rare earth metal-doped nanoparticles encapsulated in human serum albumin nanocomposites (ReANCs). ReANCs were chemically conjugated with anti-CD8α antibodies as targeting ligands to facilitate binding of the nanoprobes to CTLs with high specificity in a syngeneic mouse model of breast cancer. After treating the mice with combination anti-PD-1 and doxorubicin, volumetric analysis of the mammary fat pad tumors did not show any significant impact of treatment compared to single treatment and untreated control mice. However, increased CTL infiltration in the tumors of mice that received combination treatment was detected by in vivo SWIR imaging. CTL infiltration was validated with ex vivo IHC staining, and a monotonic relationship was observed between SWIR fluorescence and CD8 positivity. IHC staining of other immune markers, including CD45, CD3, CD4, and PD-L1, showed that combination treatment may influence in the expression of these markers, presenting additional targets that could be imaged with ReANCs in the future. In conclusion, the increase in SWIR signal from CD8-targeted ReANCs in tumors treated with combination immunotherapy and chemotherapy and the relationship with IHC staining highlight the ability to use SWIR imaging for non-invasive assessment of changes in immune dynamics following treatment. Citation Format: Jay V. Shah, Jake N. Siebert, Xinyu Zhao, Shuqing He, Richard E. Riman, Mei Chee Tan, Mark C. Pierce, Edmund C. Lattime, Vidya Ganapathy, Prabhas V. Moghe. Non-invasive shortwave infrared imaging of cytotoxic T lymphocyte infiltration for monitoring responses to combination immunotherapy and chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4178.

Real-time visualization of dextran extravasation in intermittent hypoxia mice using noninvasive SWIR imaging.

Imaging tools are crucial for studying the vascular network and its barrier function in various physiopathological conditions. Shortwave infrared (SWIR) window optical imaging allows noninvasive, in-depth exploration. We applied SWIR imaging, combined with vessel segmentation and deep learning analyses, to study real-time dextran probe extravasation in mice experiencing intermittent hypoxia (IH)-a characteristic of obstructive sleep apnea associated with potential cardiovascular alterations due to early vascular permeability. Evidence for permeability in this context is limited, making our investigation significant. C57Bl/6 mice were exposed to normoxia or intermittent hypoxia for 14 days. Then SWIR imaging between 1,250 and 1,700 nm was performed on the saphenous artery and vein and on the surrounding tissue after intravenous injection of labeled dextrans of two different sizes (10 or 70 kDa). Postprocessing and segmentation of the SWIR images were conducted using deep learning treatment. We monitored high-resolution signals, distinguishing arteries, veins, and surrounding tissues. In the saphenous artery and vein, after 70-kD dextran injection, tissue/vessel ratio was higher after intermittent hypoxia (IH) than normoxia (N) over 500 seconds (P < 0.05). However, the ratio was similar in N and IH after 10-kD dextran injection. The SWIR imaging technique allows noninvasive, real-time monitoring of dextran extravasation in vivo. Dextran 70 extravasation is increased after exposure to IH, suggesting an increased vessel permeability in this mice model of obstructive sleep apnea.NEW & NOTEWORTHY We demonstrate that SWIR imaging technique is a useful tool to monitor real-time dextran extravasation from vessels in vivo, with a high resolution. We report for the first time an increased real-time dextran (70 kD) extravasation in mice exposed to intermittent hypoxia for 14 days compared with normoxic controls.

Shortwave infrared and visible light image fusion method based on dual discriminator GAN

In a tactical warfare setting, the efficacy of target detection becomes profoundly compromised due to prevalent environmental factors such as smoke, dust, and atmospheric interference. Such impediments invariably undermine the precision and reliability of identifying pivotal targets, thereby precipitating potentially dire ramifications. Remarkably, short-wave infrared technology has exhibited unparalleled proficiency in elucidating target attributes even amidst challenging conditions characterized by smoke, fog, or haze. Against this backdrop, the present study delineates a pioneering algorithmic framework that seamlessly amalgamates the imperatives of image registration and fusion. This is achieved through the deployment of an advanced dual-discriminator Generative Adversarial Network (GAN), specifically tailored for amalgamating short-wave infrared and visible light imagery within smoke-obscured contexts. Our methodology commences with the introduction of an augmented Speeded-Up Robust Features (SURF) algorithm, meticulously designed to rectify inherent misalignments within the input imagery. Subsequent enhancements encompass the refinement of the generator’s loss function and the integration of a multi-scale convolutional kernel, thereby facilitating the extraction and amalgamation of a more expansive array of salient features. This concerted effort culminates in the elevation of image fusion quality. To corroborate the efficacy and robustness of our proposed framework, rigorous validation procedures were conducted utilizing a meticulously curated dataset comprising short-wave infrared and visible light images. Empirical evaluations, encompassing both subjective and objective comparative analyses, unequivocally affirm the superior performance metrics of our fusion network. Specifically, our methodology surpasses alternative fusion techniques across multiple dimensions, including visual fidelity, perceptual quality, and structural congruence of synthesized images.

Low dark current lateral Ge PIN photodetector array with resonant cavity effect for short wave infrared imaging

High-performance germanium (Ge) lateral PIN photodetector (PD) arrays for short wave infrared (SWIR) imaging based on Ge-on-insulator (GOI) platform was proposed and demonstrated. The high-quality GOI platform with top-Ge layer thickness of 1.25 μm and threading dislocation density of less than 105 cm−2 was prepared by using bonding and smart-cut technology. P-type and N-type regions with centrosymmetric racetrack shapes were introduced to lower the sidewall electric field and suppress the surface leakage current of the PD. Benefiting from the high-quality of the GOI platform and the unique design of lateral active regions, a low dark current of 2 nA under −1 V with outstanding rectification ratio of 2.1 × 106 were obtained at room temperature. Through constructing a vertical resonant cavity by SiO2 passivation layer and the Si/SiO2 substrate, the responsivity at 1550 nm was enhanced to 0.46 A W−1 with a high specific detectivity of 3.09 × 1010cm·Hz1/2 ·W−1 under −1 V. Ultimately, SWIR imaging was demonstrated by a Ge lateral PIN PD line array with 1 × 8 pixels under zero bias at room temperature. The results indicate that the proposed lateral Ge PD structure holds great application potential in the field of SWIR imaging.

Suppressing the Dark Current While Improving the Quantum Efficiency in Shortwave Infrared Organic Photodetectors Through Naphthalenediimide‐Based Interlayer

AbstractThe significance of shortwave infrared (SWIR) photodetectors spans across various applications. Nevertheless, the limited spectral response of silicon‐based photodetectors and the high cost associated with materials like germanium (Ge) have impeded the widespread adoption of SWIR sensors, particularly in the realm of consumer electronics. This study explores the transformative impact of incorporating a cross‐linkable naphthalenediimide (c‐NDI) as both an electron transporting layer and a hole blocking layer in organic photodetectors (OPDs). The introduction of c‐NDI as an interlayer leads to substantial enhancements in SWIR OPD performance, particularly in terms of reducing dark current and augmenting external quantum efficiency. These improvements are most notable in ultra‐narrow bandgap SWIR systems, where c‐NDI demonstrates superior hole‐blocking capabilities. Besides, OPDs with c‐NDI interlayers also exhibit exceptional stability over time when compared to OPDs based on zinc oxide interlayer, underscoring c‐NDI‘s versatility as an interlayer. Most importantly, when compared to a commercially available Ge photodetector, c‐NDI‐based OPD demonstrates competitive detectivity, achieving 2.67 × 1011 Jones at a wavelength of 1300 nm. This performance even surpasses that of the Ge photodetector, highlighting the substantial potential of OPDs for SWIR imaging applications.

Machine Learning-Assisted Short-Wave InfraRed (SWIR) Techniques for Biomedical Applications: Towards Personalized Medicine.

Personalized medicine transforms healthcare by adapting interventions to individuals' unique genetic, molecular, and clinical profiles. To maximize diagnostic and/or therapeutic efficacy, personalized medicine requires advanced imaging devices and sensors for accurate assessment and monitoring of individual patient conditions or responses to therapeutics. In the field of biomedical optics, short-wave infrared (SWIR) techniques offer an array of capabilities that hold promise to significantly enhance diagnostics, imaging, and therapeutic interventions. SWIR techniques provide in vivo information, which was previously inaccessible, by making use of its capacity to penetrate biological tissues with reduced attenuation and enable researchers and clinicians to delve deeper into anatomical structures, physiological processes, and molecular interactions. Combining SWIR techniques with machine learning (ML), which is a powerful tool for analyzing information, holds the potential to provide unprecedented accuracy for disease detection, precision in treatment guidance, and correlations of complex biological features, opening the way for the data-driven personalized medicine field. Despite numerous biomedical demonstrations that utilize cutting-edge SWIR techniques, the clinical potential of this approach has remained significantly underexplored. This paper demonstrates how the synergy between SWIR imaging and ML is reshaping biomedical research and clinical applications. As the paper showcases the growing significance of SWIR imaging techniques that are empowered by ML, it calls for continued collaboration between researchers, engineers, and clinicians to boost the translation of this technology into clinics, ultimately bridging the gap between cutting-edge technology and its potential for personalized medicine.

Spectral routers for snapshot multispectral imaging

Snapshot spectral imaging aims at capturing full spatial and spectral information simultaneously. It can benefit greatly from a photon-efficient spectral decomposition that does not sacrifice spatial resolution. The multispectral filter arrays that enable compact single-chip snapshot multispectral imaging, however, suffer from fundamental and important limitations: low photon efficiency and low spatial resolution. Here, we introduce a spectral router for snapshot multispectral imaging to address these limitations. A spectral router routes all light incident on its entire surface directly to the photodetector of each spectral channel without need for a propagation layer between the router and the detector. Unlike filters, spectral routers do not reject light to achieve spectral selectivity and can ideally exploit 100% of the incident light. Spectral routers also break the size barrier that exists for filter arrays and can be designed with wavelength size footprint. This enables spectral routers to simultaneously provide spectral information as well as spatial information at higher spatial resolution, and can even allow them to provide spectral information without sacrificing spatial information beyond the diffraction limit. We illustrate the concept with two examples. A first spectral router covers the visible range and can achieve ideal optical efficiency for six spectral channels in a sub-micrometer footprint, which is 15 times smaller than a filter array repeat unit with the smallest Fabry–Pérot filters. The second example covers the shortwave infrared (SWIR) range with nine spectral channels and is suitable for pixels that are two times smaller than the smallest SWIR imager pixels demonstrated to date.

Double‐ended passivator enables dark‐current‐suppressed colloidal quantum dot photodiodes for CMOS‐integrated infrared imagers

AbstractLead sulfide (PbS) colloidal quantum dot (CQD) photodiodes integrated with silicon‐based readout integrated circuits (ROICs) offer a promising solution for the next‐generation short‐wave infrared (SWIR) imaging technology. Despite their potential, large‐size CQD photodiodes pose a challenge due to high dark currents resulting from surface states on non‐passivated (100) facets and trap states generated by CQD fusion. In this work, we present a novel approach to address this issue by introducing double‐ended ligands that supplementally passivate (100) facets of halide‐capped large‐size CQDs, leading to suppressed bandtail states and reduced defect concentration. Our results demonstrate that the dark current density is highly suppressed by about an order of magnitude to 9.6 nA cm−2 at −10 mV, which is among the lowest reported for PbS CQD photodiodes. Furthermore, the performance of the photodiodes is exemplary, yielding an external quantum efficiency of 50.8% (which corresponds to a responsivity of 0.532 A W−1) and a specific detectivity of 2.5 × 1012 Jones at 1300 nm. By integrating CQD photodiodes with CMOS ROICs, the CQD imager provides high‐resolution (640 × 512) SWIR imaging for infrared penetration and material discrimination.image

Shortwave‐Infrared‐Emitting Nanoprobes for CD8 Targeting and In Vivo Imaging of Cytotoxic T Cells in Breast Cancer

Checkpoint immunotherapy has made great strides in the treatment of solid tumors, but many patients do not respond to immune checkpoint inhibitors. Identification of tumor‐infiltrating cytotoxic T cells (CTLs) has the potential to stratify patients and monitor immunotherapy responses. In this study, the design of cluster of differentiation (CD8+) T cell‐targeted nanoprobes that emit shortwave infrared (SWIR) light in the second tissue‐transparent window for noninvasive, real‐time imaging of CTLs in murine models of breast cancer is presented. SWIR‐emitting rare‐earth nanoparticles encapsulated in human serum albumin are conjugated with anti‐CD8α to target CTLs with high specificity. CTL targeting is validated in vitro through binding of nanoprobes to primary mouse CTLs. The potential for the use of SWIR fluorescence intensity to determine CTL presence is validated in two syngeneic mammary fat pad tumor models, EMT6 and 4T1, which differ in immune infiltration. SWIR imaging using CD8‐targeted nanoprobes successfully identifies the presence of CTLs in the more immunogenic EMT6 model, while imaging confirms the lack of substantial immune infiltration in the nonimmunogenic 4T1 model. In this work, the opportunity for SWIR imaging using CD8‐targeted nanoprobes to assess CTL infiltration in tumors for the stratification and monitoring of responders to checkpoint immunotherapy is highlighted.

The quantum revolution in vehicle sensor technology

AbstractWith technology like lidar heralding a revolution in vehicle automation, SWIR (short‐wave infrared) imaging and sensing will become increasingly vital to the automotive sector. Quantum dots, nanoscale semiconductors tunable to SWIR wavelengths, could provide the answer to empowering SWIR and bringing enhanced capability to the mass market.