Near-infrared Research Articles

Persistent Luminescence for Night‐Time Individual Identification Based on Quantum Tunneling

AbstractNight‐time individual identification requires recognizing a specific object from a bunch of homogeneous entities through night‐vision devices. It will facilitate more effective coordinated actions in night‐time disaster rescue or enforcement actions. In this work, the near infrared (NIR) persistent luminescent materials are proposed as the technology solution, which can emit the non‐visible photons continuously for hours without the external excitation. In a magnetoplumbite‐type structure, Cr3+ ions are incorporated to realize NIR emissions. By co‐doping lanthanide ions and constitutional modulation, the afterglow signal can be clearly traced under the night‐vision device over 144 h. A series of spectral measurements are utilized to reveal the mechanism behind this prolonged afterglow duration, and quantum tunneling accounts for the carrier pumping from the deep traps. It avoids the quick exhaust of carriers stored in the shallow traps, and extends the afterglow duration. In a proof‐of‐concept demonstration, the synthesized powders are used to make a quick response pattern, which can be clearly visualized in a dark room by the night‐vision devices. This work is expected to promote the research and development of persistent luminescent materials within NIR region, and to accelerate the applications in night‐time monitoring and recognition.

Establishing Optimal Machine Learning Models for Monitoring Water Quality in Vietnam’s Upper Ma River

This study aims to establish the optimal regression model for predicting total suspended solids (TSS) and Turbidity based on in situ data and spectral regions of Sentinel-2 images. Various machine learning models were evaluated, including Multilayer Perceptron Regression (MLPR), Random Forest Regression (RFR), AdaBoost Regression (ABR), Multiple Linear Regression (MLR), and K-Nearest Neighbors Regression (KNNR). These models were applied to different band combinations of spectral regions: visible (VIS), near-infrared (NIR), shortwave-infrared (SWIR), VIS+NIR (VNIR), and VIS+NIR+SWIR (VNIR+SWIR). The study results revealed that the MLR model, while not the best performer during training (R2 = 0.89 for TSS and R2 = 0.66 for turbidity), did not exhibit overfitting, with corresponding R² values in testing being 0.80 and 0.42, respectively. Variable selection for MLR models identified optimal spectral bands: B3, B5, B6, B8, B11, and B12 for TSS, and B4, B8, B11, and B12 for Turbidity. The final no-intercept multiple linear regression models achieved R2 = 0.88 for TSS and R2 = 0.62 for turbidity. Performance metrics for TSS were superior, with lower MAE, MSE, and RMSE compared to Turbidity. This study underscores the efficacy of using MLR models with selected spectral bands for accurate and generalizable predictions of TSS and turbidity.

6.7–8.1 µm tunable single-frequency difference frequency generation in ZGP for high-resolution spectroscopy

Difference frequency generation (DFG) based tunable single-frequency mid-infrared (MIR) light sources are desirable for high-resolution spectroscopy, sensing, and imaging. In this work, we demonstrate a continuous-wave (CW) single-frequency DFG in a ZnGeP2 (ZGP) crystal driven by all-fiber near-infrared (NIR) fiber lasers, for the first time to our knowledge. The all-fiber NIR laser sources consist of a 1.5 µm erbium-doped fiber amplifier seeded by a CW tunable fast scanning single-frequency laser and a 1.9 µm CW tunable single-frequency thulium-doped fiber laser. Taking advantage of the high nonlinear coefficient and large birefringence of the ZGP crystal, single-frequency DFG in ZGP achieves a broad spectral tuning range from 6.7 to 8.1 µm, with an output power at the 10 µW level. Precise detection of C2H2 gas by continuously scanning the DFG source across a spectral range of 1.1 THz (∼34 cm−1) is also presented, highlighting the potential of the tunable DFG source for high-resolution optical spectroscopy applications. We anticipate this work will provide what we believe to be a new platform for spectroscopy in the molecular fingerprint spectral region.

Quasi-Single-Crystal Tin Halide Perovskite Films with High Structural Integrity for Near-Infrared Imaging Array Enabling Hidden Object Recognition.

Near-infrared (NIR) image sensors based on solution-processed thin film are gaining prominence in various applications, including security detection, remote sensing, medical imaging, and environmental monitoring, owing to superior penetration capabilities of NIR light. However, the reported perovskite image sensors suffer from limited resolution and performance due to poor structural integrity, bioincompatibility, and constrained response wavelength range from lead-based perovskite materials employed. In this study, we present non-toxic quasi-single-crystal (QSC) CH(NH2)2SnI3 (FASnI3) perovskite films, prepared via a simple spin-coating technique, that demonstrate high structural integrity and effective NIR response. Through a series of in situ characterizations, we reveal that the orderly growth mode of QSC-FASnI3 perovskite films enables a more oriented crystal growth with reduced trap and grain boundaries. Consequently, self-powered NIR photodetector based on QSC-FASnI3 films exhibited large detectivity over 1013 Jones in the NIR range (780-890 nm). Ultimately, due to the high structural integrity, the high-resolution 64×64 (4096) pixels NIR imaging array, exhibiting reduced photo and dark response non-uniformity value, was fabricated on the thin-film transistors (TFT) backplanes, enabling ultraweak NIR light (63 nW cm-2) real-time imaging, fingerprint imaging, and hidden object recognition. This work pioneers the application of lead-free perovskite for high-resolution NIR imaging arrays.

Design of a High-Performance Near-Infrared Scintillator through Metal-Atom Substitution in Metal Chalcogenide.

We report the synthesis and optical characterization of a series of metal chalcogenides, A3SiS4Te (A = Sr2+, Ba2+, Eu2+), highlighting the metal-atom substitution strategy for the discovery of a high-performance metal chalcogenide-based near-infrared (NIR) scintillator of Eu3SiS4Te. Eu3SiS4Te exhibits exceptionally broad NIR emission with a full width at half-maximum of 210 nm, the largest among all known Eu2+-based NIR emitters. Eu3SiS4Te has a high light yield of 41697 photons/MeV and excellent resistance to hygroscopicity. Additionally, Eu3SiS4Te boasts a decay time of 531.3 ns, which is merely a quarter of that of the current state-of-the-art NIR scintillators. As a proof of concept, the response to the 241Am radioactive source was successfully identified, underscoring its potential for γ-photon-counting applications.

Near-infrared spectroscopy-enabled electromechanical systems for fast mapping of biomechanics and subcutaneous diagnosis.

Fast and accurate assessment of skin mechanics holds great promise in diagnosing various epidermal diseases, yet substantial challenges remain in developing simple and wearable strategies for continuous monitoring. Here, we present a design concept, named active near-infrared spectroscopy patch (ANIRP) for continuously mapping skin mechanics. ANIRP addresses these challenges by integrating near-infrared (NIR) sensing with mechanical actuators, enabling rapid measurement (<1 s) of Young's modulus, high spatial sensing density (~1 cm2), and high spatial sensitivity (<1 mm). Unlike conventional electromechanical sensors, NIR sensors precisely capture vibrational frequencies propagated from the actuators without needing ultraclose contact, enhancing wearing comfort. Demonstrated examples include ANIRPs for comprehensively moduli mapping of artificial tissues with varied mechanical properties emulating tumorous fibrosis. On-body validation of the ANIRP across skin locations confirms its practical utility for clinical monitoring of epidermal mechanics, promising considerable advancements in real-time, noninvasive skin diagnostics and continuous health monitoring.

Fluorescent Coating through Melanisation of Merocyanine Based on Catechol Chemistry.

In this study, we present a novel approach for synthesising a merocyanine (MC) compound that integrates gallol and a near‑infrared (NIR) fluorophore using a straightforward method. We conduct a comprehensive structural analysis to elucidate the specific roles of each functional group during monomer synthesis and their effects on the properties of both the spiropyran (SP) and MC forms, particularly their fluorescence. As a proof of concept, we explore the use of these compounds in formulating innovative fluorescent polymeric coatings by melanising catechol and gallol moieties on various substrates, including glass, a cupronickel coin, and an organic polymer. To our knowledge, this is the first report of a bioinspired approach utilizing the melanisation of a catechol and gallol moiety containing merocyanine.

Metal-phenolic nanoparticles enhance low temperature photothermal therapy for bacterial biofilm in superficial infections.

Bacterial infections, especially induced by multidrug-resistant pathogens, have become a significant global health concern. In the infected tissues, biofilms not only serve as a source of nutrients but also act as protective barriers that impede antibiotic penetration. Herein, we developed tea polyphenols epigallocatechin gallate (EGCG) Au nanoparticles (E-Au NPs) through direct one-step self-assembly methods by EGCG chelating with Au ions to eradicate antibiotic-resistant bacteria methicillin-resistant Staphylococcus aureus (MRSA) and prevent the formation of biofilm under near-infrared (NIR) irradiation. The outstanding antibacterial effect involved in mild photothermal therapy, reactive oxygen species production, pathogenicity-related genes regulation, and quinoprotein formation that were specific to the polyphenol-based NPs. The excellent antibacterial and anti-inflammatory therapeutic efficacy of E-Au NPs was validated and topically applied in murine MRSA-infected skin wounds and keratitis model in vivo to kill bacteria, reduce the inflammation response and promote wound healing. Furthermore, the ophthalmic and systemic biosafety profiles were thoroughly evaluated while no significant side effects were revealed achieving a balance between high-efficiency antibacterial properties and biocompatibility. This study provides an effective therapeutic agent of metal-phenolic materials for superficial tissue infection with favorable prognosis and potential in clinical translation.

FeS2@COF based nanocarrier for photothermal-enhanced chemodynamic/thermodynamic tumor therapy and immunotherapy via reprograming tumor-associated macrophages.

Developing high-performance nanomedicines to enhance antitumor efficacy remains a hot point in the field of biomedicine. In this study, we designed a versatile nanocomposite (FeS₂@COF-HA/AIPH) integrating covalent organic frameworks (COF) functionalized with pyrite (FeS₂) for synergistic photothermal (PTT), chemodynamic (CDT), thermodynamic (TDT) therapies, and immunotherapy. The superior photothermal effects and catalytic capabilities of FeS₂@COF enabled a minimally invasive PTT/CDT combination. The nanoplatform, with its mesoporous structure, also served as a drug delivery system, encapsulating the thermos-decomposable initiator AIPH. The hyaluronic acid (HA) coating not only improved tumor-targeting efficiency but also prevented nonspecific AIPH release. Under near-infrared (NIR) irradiation, the localized hyperthermia triggered AIPH decomposition, generating toxic alkyl radicals (•R) for TDT, further enhancing CDT efficiency. The combination of PTT, CDT, TDT, and immunotherapy led to potent antitumor effects with minimal systemic toxicity, both in vitro and in vivo. Notably, the nanoplatform effectively reprogrammed tumor-associated macrophages (TAMs) from an M2 to M1 phenotype, boosting antitumor immunity. This multifunctional platform thus offers a promising strategy for integrated PTT, CDT, TDT, and immune activation in tumor therapy.

Superhydrophilic Fluorinated Polymer Probe for Zero-Background 19F MRI with Adaptable Targeting Ability.

19F magnetic resonance imaging (19F MRI), with zero background, high tissue penetration depth, excellent spatial resolution, and nonradioactive features, has attracted considerable attention but faces tough challenges due to the shortage of sensitive and selective targetable probes. Herein, we report a biocompatible and highly sensitive 19F MRI probe with an adaptable tumor-targeting ability. The fluorine-grafted polymer (PIBMA-FSON) probes were rich with sulfoxide and carboxy groups, containing a high fluorine content (∼17 wt %). The probes exhibit superhydrophilicity, strong 19F MRI signals (enhancement of ∼95-fold), long transverse relaxation time (T2, 422 ms), and excellent 19F MRI capability. Conjugation using a targeting peptide (Arg-Gly-Asp, RGD) afforded ultrasmall soft polymer probes (PIBMA-FSON-RGD) with superhydrophilicity and tumor-targeting ability suitable for the 19F MRI of orthotopic bladder cancer. Amidification of 5% of the carboxylate units with oleylamine resulted in PIBMAOAm-FSON nanoprobes (NPs) via self-assembly, displaying different targeting toward subcutaneous tumors. Further grafting with near-infrared (NIR) dyes renders the probe suitable for NIR-fluorescence and 19F MRI dual-modality imaging. This study provides a suitable approach for designing highly sensitive and zero-background 19F MRI probes with a tunable tumor-targeting ability.

Development of a hybrid CuS-ICG polymeric photosensitive vector and its application in antibacterial photodynamic therapy.

At the present time, owing to the extremely high growth of microbial resistance to antibiotics and, consequently, the increased healthcare associated costs and the loss of efficacy of current treatments, the development of new therapies against bacteria is of paramount importance. For this reason, in this work, a hybrid synergetic nanovector has been developed, based on the encapsulation of a NIR (near infrared) photosensitive molecule (indocyanine green, ICG) in biodegradable polymeric nanoparticles (NPs). In addition, copper sulfide nanoparticles (CuS NPs), optically sensitive to NIR, were anchored on the polymeric nanoparticle shell in order to boost the generation of reactive oxygen species (ROS) upon NIR irradiation. As a result, the nanohybrid synthesized material is capable to generate ROS on demand when exposed to a NIR laser (808nm) allowing for the repeated triggering of ROS production upon NIR light exposure. After each irradiation, the ROS generated were able to eliminate pathogenic bacteria, as it was demonstrated in-vitro with three bacterial strains, Staphylococcus aureus ATCC 25923 used as a reference strain (S. aureus), S. aureus USA300 (methicillin-resistantstrain, MRSA) and GFP-expressing antibiotic-sensitive S. aureus (methicillin-sensitive strain, MSSA). Finally, the effect of the hybrid NPs in the skin bed was tested on a plasma-derived in vitro skin model. Fluorescence and histological images showed the presence of CuS NPs all over the dermal layer lacking epidermis of the skin construct. Thus, the in vitro model facilitated the prediction of the nanovector's behavior in a human skin equivalent, showcasing its potential application against topical infections after wounding.

Germanium-incorporated Si-Ge-Si heterojunction phototransistors for a high-limit of detection and wide linear dynamic range near-infrared light detection

This paper investigates overcoming the limitations of conventional silicon (Si) bipolar junction transistors (BJTs) for near-infrared (NIR) light detection. Silicon BJTs have inherent limitations in the NIR region due to silicon’s bandgap. To address this, the paper proposes high-performance silicon-germanium-silicon (Si-Ge-Si) heterojunction bipolar phototransistors (HPTs). The key innovation is introducing a thin germanium (Ge) layer at the base-collector junction and engineering its doping concentration. This Ge layer extends the BJT phototransistor’s optical response into the NIR region by enhancing optical absorption. The paper analyses the performance of the HPTs, demonstrating linear photoresponsivity of 432 mA/W over a wide optical power range, leading to an exceptional linear dynamic range of 159 dB and a very low dark current, which produces a limit of detection of -99.64 dBm. Additionally, the device exhibits a large photo-to-dark current ratio of 2.16 ×107 (at optical power of 5 µW) and a fast response time of 11.35 ps to modulated NIR optical signals within the linear dynamic range. This research paves the way for high-performance CMOS-compatible NIR phototransistors using Si-Ge-Si heterostructures.

Comparison between consumer-oriented and laboratory benchtop near-infrared spectrometers for total soluble solids measurement in grape

Portable near-infrared (NIR) spectrometers are gaining interest as a non-destructive tool for fruit quality determination in the decade. In this study, the performance of the portable NIR spectrometer for TSS prediction of grapes was evaluated and compared to the benchtop spectrometer. A total of 105 table grapes were individually measured NIR spectra at short-wavelength (740 – 1070 nm) and long-wavelength NIR region (1000 – 2500 nm) using SCiO and NIRFlex N-500 spectrometers, respectively. Partial least square (PLS) regression analysis was performed on berry spectra from both devices afterward significant wavelengths were identified and used to develop multiple linear regression (MLR) models. The best PLS prediction model was obtained from SNV pretreating spectra for both devices and spectral data acquired from SCiO showed better prediction performance (= 0.854, SEP = 0.452°Brix) than NIRFlex N-500 spectra (= 0.667, SEP = 0.675°Brix). Low predicting ability was gained for the MLR calibration model for both device with an RPD of about 1.70. From the results, a pocket-size spectrometer has the potential to be a non-destructive sorting and screening tool in fruit industries.

Numerical study of a tapered fiber magnetic field sensor based on the ENZ mode

This study introduces what we believe to be a novel magnetic field sensor that utilizes a tapered optical fiber coated with indium tin oxide (ITO) and titanium dioxide (TiO2), operating on an epsilon-near-zero (ENZ) mode. The evanescent field around the tapered optical fiber can excite the ENZ mode of the ITO film, and the TiO2 layer can ensure the phase matching between the fiber core mode and the ENZ mode. The sensor, immersed in magnetic fluid, leverages the unique properties of ENZ materials to achieve a high sensitivity and resolution in the near-infrared (NIR) region. Through a simulation, the sensor demonstrated a maximum sensitivity of 6900 nm/RIU and a magnetic field sensitivity of 370 pm/Oe. The findings suggest that ENZ mode-based optic sensing presents a promising alternative to traditional plasmonic sensing methods, offering potential applications in various fields requiring precise magnetic field measurements.

Enhancing Near-Infrared Photothermal Performance by Molecular Aggregation Optimization in Semiconductive Coordination Polymers.

Near-infrared (NIR) photothermal conversion materials have recently received widespread attention due to their potential in diverse applications. However, highly efficient organic-based NIR photothermal agents remain limited. Developing strategies to enhance the efficiency of NIR photothermal materials and elucidating the relationship between the NIR photothermal performance and molecular aggregation are highly desired. Herein, we report two coordination polymers {[Cd2(ONDI)(ox)]·2/3(H2O)}n (1) and [Ba(ONDI)(H2O)2]n (2), in which the ONDI2- ligands assemble into different π-π stacking arrangements. Compound 1 exhibits H-aggregation, while compound 2 displays X-aggregation. The X-aggregation in compound 2 extends the optical absorption into the NIR region and enhances the absorption intensity. Consequently, compound 2 demonstrates a 1.8-fold increase in NIR photothermal efficiency (68.6%) compared to compound 1 (38.8%), attributed to more effective π-π interactions in X-aggregation. In addition, both compounds show semiconductive properties, with conductivities of 2.1 × 10-7 S/cm for compound 1 and 3.0 × 10-7 S/cm for compound 2 at 30 °C in a nitrogen atmosphere. These properties arise from the synergistic effects of "band-like" charge transport within crystals and "hopping" charge transport across grain boundaries. By integration of their NIR photothermal effects and semiconductive properties, compounds 1 and 2 show interesting NIR photoelectrical responses.

Atomically Precise Fluorescent Gold Nanocluster as a Barrier-Permeable and Brain-Specific Imaging Probe.

Photonic nanomaterials play a crucial role in facilitating the necessary signal for optical brain imaging, presenting a promising avenue for early diagnosis of brain-related disorders. However, the blood-brain barrier (BBB) presents a significant challenge, blocking the entry of most molecules or materials from the bloodstream into the brain. To overcome this, photonic nanocrystals in the form of gold clusters (LAuC) with size less than 3 nm, have been developed, with Levodopa conjugated to LAuC (Dop@LAuC) for targeted brain imaging. Dop@LAuC crosses the BBB and emits in the near-infrared (NIR) wavelength, enabling real-time optical brain imaging. An in vitro BBB model using brain endothelial cells showed that 50 % of Dop@LAuC crossed the barrier within 3 hours, compared to only 10 % of LAuC, highlighting the enhanced ability of L-dopa-conjugated gold clusters to penetrate the BBB. In vivo optical imaging in healthy mice further confirmed the material's efficacy to cross BBB without compromising the barrier integrity.

Combination of gold nanoparticles with near-infrared light as an alternative approach for melanoma management.

Melanoma is the most aggressive type of skin cancer and recently approved drugs are often associated with resistance and significant adverse effects. Therefore, the design of more effective and safe options remains imperative. Photothermal therapy (PTT) using gold nanoparticles (AuNPs) presents a promising and innovative approach. In this work, the efficacy of combining a previously optimized formulation of AuNPs coated with a mixture of hyaluronic and oleic acids (HAOA-AuNPs) with near-infrared (NIR) laser irradiation in melanoma cell lines was explored. Coated and uncoated AuNPs formulations were characterized in physicochemical, morphological and elemental terms. Next, the cellular uptake efficiency as well as antiproliferative activity of the combination of each formulation with laser irradiation was evaluated. Subsequently, HAOA-AuNPs were selected to assess the underlying mechanism of combined therapy by cell cycle and Annexin V/PI assays. An in vivo syngeneic murine melanoma model was also conducted. In vitro studies demonstrated that 24 h after incubation and in the absence of laser, HAOA-AuNPs did not exhibit cytotoxic effects on the melanoma cell lines tested, similar to the laser alone. On the contrary, the combination therapy resulted in a large reduction in cell viability. Furthermore, it has been shown to promote S-phase cell cycle arrest and increase in the percentage of late apoptotic cells. Finally, the in vivo proof-of-concept showed that the intratumoral administration of HAOA-AuNPs followed by three laser irradiations impaired tumor progression. Collectively, AuNP-based PTT holds significant potential to improve treatment efficacy and safety, offering a versatile and potent tool against cancer.

Multifunctional Near-Infrared Luminescence Performance of Nd3+ Doped SrSnO3 Phosphor

The phosphors with persistent luminescence in the NIR (near-infrared) region and the NIR-to-NIR Stokes luminescence properties have received considerable attention owing to their inclusive application prospects in the in vivo imaging field. In this paper, Nd3+ doped SrSnO3 phosphors with remarkable NIR emission performance were prepared using a high temperature solid state reaction method; the phase structure, morphology, and luminescence properties were discussed systematically. The SrSnO3 host exhibits broadband NIR emission (800–1300 nm) with absorptions in the near ultraviolet region. Nd3+ ions emerge excellent NIR-to-NIR Stokes luminescence under 808 nm laser excitation, with maximum emission at around ~1068 nm. The concentration-dependent luminescence properties, temperature dependent emission, and the luminescence decay curves of Nd3+ in the SrSnO3 host were also studied. The Nd3+ doped SrSnO3 phosphors exhibit exceptional thermal stability; the integrated emission intensity can retain approximately 66% at 423 K compared to room temperature. Most importantly, NIR persistent luminescence also can be observed for the SrSnO3:Nd3+ samples, which is in the first and second biological windows. A possible mechanism was proposed for the persistent NIR luminescence of Nd3+ based on the thermo-luminescence spectra. Consequently, the exciting results indicate that multifunctional NIR luminescence has been successfully realized in the SrSnO3:Nd3+ phosphors.

Core-shell upconversion nanoparticles with suitable surface modification to overcome endothelial barrier.

Upconversion nanoparticles (UCNPs), capable of converting near-infrared (NIR) light into high-energy emission, hold significant promise for bioimaging applications. However, the presence of tissue barriers poses a challenge to the effective delivery of nanoparticles (NPs) to target organs. In this study, we demonstrate the core-shell UCNPs modified with cationic biopolymer, i.e., N, N-trimethyl chitosan (TMC), can overcome endothelial barriers. The core-shell UCNP is composed of NaGdF4: Yb3+,Tm3+ (16.7 ± 2.7 nm) as core materials and silica (SiO2) shell. The average particle size of UCNPs@SiO2 is estimated at 26.1 ± 3.7 nm. X-ray diffraction (XRD), transmission electron microscopy (TEM) and element mapping shows the formation of hexagonal crystal structure of β-NaGdF4 and elements doping. The surface of UCNPs@SiO2 has been modified with poly(ethylene glycol) (PEG) to enhance water dispersibility and colloidal stability, and further modified with TMC with the zeta potential increasing from -2.1 ± 0.96 mV to 26.9 ± 12.6 mV. No significant toxic effect is imposed to HUVECs when the cells are treated with core-shell UCNPs with surface modification up to 250 µg/mL. The transport ability of the core-shell UCNPs has been evaluated by using the in vitro endothelial barrier model. Transepithelial electrical resistance (TEER) and immunofluorescence staining of tight junction proteins have been employed to verify the integrity of the in vitro endothelial barrier model. The results indicate that the transport percentage of the UCNPs@SiO2 with PEG and TMC through the model is up to 4.56%, which is twice higher than that of the UCNPs@SiO2 with PEG but without TMC and six times that of the UCNPs@SiO2.

Synthesis of SrZnOSe Crystals with Low Phonon Energy for Enhancing Near-Infrared Mechanoluminescence.

Near-infrared (NIR) light is promising for bioimaging and information technology due to its high penetration ability and resistance to interference with environmental radiation. Here, a new class of lanthanide-doped SrZnOSe crystals are developed for the self-sustainable generation of NIR emissions under mechanical excitation. It is shown that the SrZnOSe crystals render ≈5-fold stronger NIR emissions than the well-established CaZnOS due to the low phonon energies of the selenide host, as confirmed by Raman spectroscopy. The potential utility of the crystals is demonstrated by integration with a mouthguard, which can generate bright NIR emissions by bite force to transmit encrypted optical signals through thick tissues (up to 8mm) in ambient environments. The findings provide a powerful addition to the toolbox of self-recovery mechanoluminescent materials and open new possibilities for applied research.