Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XXII

Cellulose-based materials contain many advantageous and versatile properties and cellulose-based materials have existed for many millennia. Plants can program cellulose-based dead tissues to respond to external stimuli, usually water. The awns of the Erodium fruit, present amazing coil and uncoil motions in response to humidity. These movements result from anisotropic cellulose-based materials organized in layers that contract differently upon the presence of humidity. Cellulose ribbons, if produced from liquid crystalline solutions, are responsive to moisture. In this work stimuli-responsive cellulose-based liquid crystalline films produced by shear-casting techniques with a multi-layer design are evaluated to be used as humidity and temperature sensors. Preparation and characterization and their application as a flexible humidity sensor will be presented in this work. Cellulose-based Nature inspired materials have significant potential for opening up new routes for the production of novel mobile soft materials with tremendous impact on intelligent textiles, energy generation, drug delivery, bio-medical and bio-sensing devices, and micro soft robotics.

A flexible bipolar electrochemiluminescence (ECL) system was developed, with carbon nanotube (CNT) fiber serving as the bipolar electrode and bacterial nanocellulose (BNC) as the substrate material for holding biofluid sample, reaction reagents, and electrolytes. By coupling analyte-specific enzymatic reactions that produce H2O2 with luminol to produce ECL in an electric field, this system quantifies biomarkers based on the ECL intensity. The CNT fiber was incorporated into the BNC matrix in a bottom-up process by embedding CNT fiber during the synthesis of BNC, resulting in the CNT fiber being intercalated within the nanocellulose matrix to form a stable composite. Various decellularization methods of the BNC were investigated to achieve optimal purity of the nanocellulose material. The configuration of the CNT electrode was optimized based on its thickness, length, and distance relative to the driving electrodes. The system was tested with various concentrations of H2O2 and uric acid to characterize its performance.

Cellulose nanocrystals (CNCs) can spontaneously self-assemble into cholesteric mesophases exhibiting a mosaic of colours due to their multidomain structure with variation in the chiral pitch. In most studies, the self-assembly of CNCs is conducted using drop casting which brings some structural and optical artefacts to the photonic films. Here, in this presentation, I will demonstrate the ways of harnessing the Marangoni flow to produce photonic films with substrates positioned at different angles in a vertical deposition configuration. In this configuration, we identified the formation of tilted and folded domains as a function of the angular position of the substrate which has drastic effects on optical properties. This innovative self-assembly approach enables precise manipulation of substrate geometry and contact lines with the CNC suspension, providing new insights into the spontaneous particle fractionation, gelation and aggregation mechanisms.

Biotic and bioinspired photonics is emerging as the most promising strategy to enhance sustainability, resilience, and processability in nanophotonic applications. In this paper we will introduce a new metamaterials platform inspired by photosynthetic biological nanostructures. The artificial platform is formed by the combination of molecular excitonics and photonic nanostructuring in which the combination of both properties allows similar functionalities for light management found in photosynthetic. As an example, we will show that a multilayer structure formed by common polymers and organic dyes can exhibit Near Zero Index (NZI) properties. We will showcase possible strategies to produce similar photonic structures using biologically derived materials and will discuss future strategies towards bioinspired metal-free and all-organic photonic devices.

In the biomedical field, the reemitted light intensity measured from the tissue depends on both scattering and absorption. In order to separate these variables, we use a physical phenomenon discovered in our lab, called the iso-path length (IPL) point. The IPL point is a specific angle around a cylindrical media, where the light intensity is not affected by the scattering and can serve for self-calibration. For a practical use of this concept, we designed an optic biosensor for measuring physiological parameters such as blood pressure, extracted directly from the absorption.

The ability to simultaneously record nanoscale biological structures with their chemical composition has wide applicability from understanding fundamental cell biology to elucidating markers of disease progression. One promising approach leverages Atomic Force Microscopy (AFM) as a near-field detector to record infrared (IR) molecular vibrational spectroscopic contrast at the nanoscale (AFM-IR). Using AFM-IR for biological applications, however, has seen little success due detection-induced artifacts, low signal-to-noise ratio (SNR), and limited sensitivity. Here, we report our development of a fundamental theoretical understanding of the image formation process in AFM-IR and its use to actualize accurate and high-performance instrumentation that can enable routine biomedical imaging. Our technique, known as Null-Deflection Infrared (NDIR) spectroscopic imaging, enables IR molecular spectroscopic contrast at the nanoscale insensitive to artifacts with 24x improvement in noise. We demonstrate its effectiveness by imaging model cell samples, comparing results against conventional methods, and assessing performance using analytical models of image formation.

Selective cell fusion is a valuable tool for studying and triggering various key processes in biomedicine. Using amplified femtosecond laser pulses tuned to the plasmonic resonance of gold nanoparticles conjugated to specific cells, plasmonic cell fusion can trigger highly efficient, widespread fusion between the target cells. The talk will present the fundamental physics underlying plasmonic fusion, describe the unique technological challenges and capabilities of this approach, and outline various demonstrations of the technique, including stimulating selective immune response by fusing together malignant and immune-system cells, and treating muscle injuries by selective fusion between fibroblasts and skeletal muscle cells.

The detection of cancer-related circulating biomarkers in body fluids has tremendous prevalence for cancer screening, diagnosis of cancer in its early stages, monitoring of cancer development, and evaluation of the response to therapy. Surface-enhanced Raman scattering (SERS) is an emerging analytical technique used for the characterization of biological and non-biological structures. In the study, a SERS-based immunosensor is developed for the single and multiplex detection of cancer protein biomarkers (human epidermal growth factor receptor 2 (HER2), mucin 4 (MUC 4), and prostate-specific antigen (PSA)) in serum on a flexible nanoporous biosilica-based SERS active platform. The results demonstrated that the nanoporous biosilica-based SERS active strip shows high sensitivity and selectivity for detecting biomarkers related to breast, prostate, and pancreatic cancers. The use of photonic biosilica in combination with plasmonic nanostructures provides a promising approach for developing ultrasensitive and multiplexed SERS-based biosensors for cancer diagnosis and monitoring.

THz frequency quantum cascade lasers (QCL) have been developed remarkably since 2002 and represent a promising solution for bridging the so-called THz technology gap. What is still required are higher-power sources that work at higher temperatures where cryogenic cooling is not necessary, being able to generate a series of ultra-short and high-intensity THz pulses, as well as more sensitive detectors. We present various modelling results of THz QCLs including numerical simulations of different GaAs/AlGaAs designs, consideration of new material platforms based on wide-bandgap semiconductors, exploration of the possibilities for ultra-short pulsing, and investigation of the THz QCL dynamics arising from self-mixing.

Colorimetric sensors offer a cost-effective, rapid, and user-friendly approach for a variety of applications, transforming medical diagnostics, environmental monitoring, and industrial processes through visible color changes. These changes result from the interaction of sensor materials with light, engineered to respond to specific stimuli. Nanoscale sensors are particularly sensitive, detecting minute environmental changes by leveraging the unique properties of nanomaterials. Despite their advantages, expensive production methods limit their widespread use. Here, we present a scalable, low-cost, non-toxic nanoplasmonic colorimetric sensor using self-assembled aluminum nanoparticles, offering high reflectance, minimal angular and polarization dependence, and easy integration with smartphone technology. This approach enables the development of accessible, portable diagnostic tools.

This study presents a novel all-optical method for super-resolved (SR) imaging using time-multiplexing with speckle illumination. Unlike conventional techniques requiring post-processing and precise knowledge of high-resolution encoding patterns, our approach generates a SR image in an all-optical computation-free manner by interfering the object's image with speckle illumination and averaging multiple speckle pattern images. The method utilizes a single wavelength and requires no a-priori knowledge of the illuminating patterns. We present theoretical analysis, numerical simulations, and experimental results, indicating resolution improvement without digital post-processing, making this technique suitable for near real-time applications. This advancement offers a simpler, faster alternative for achieving SR in optical microscopy.

Sensing or imaging using diffuse reflectance always requires a model of the light-medium interaction. A simple primary-secondary dual-source model [Piao & Patel, 2017] has been shown applicable to source-detector-separation (SDS) of ~1/10th of the reduced scattering pathlength, below which it overestimates significantly. We introduce a method to suppress the overestimation of the model at SDS <1/10th of the reduced scattering pathlength. Comparison against Monte Carlo simulations has shown that the simple modification extends the applicability of the primary-secondary dual-source approach to SDS of two-orders of magnitude smaller than previously viable. The improvement is extendable to area-integrated diffuse reflectance tested experimentally.

Understanding the light interaction with biological tissues is needed for medical assessment. Traditional methods often struggle to distinguish between the superficial and deep tissue layers. Our research utilizes a polarization-based methodology allowing to isolate the superficial layer effects, named the Q-Sensing Technique. By capturing co-polarized and cross-polarized signals, we find the Q parameter correlating with the optical properties of different phantoms. Monte Carlo simulations for polarized light were performed for this study. This research demonstrates the potential of polarized light in improving diagnostic techniques by offering deeper insights into light-tissue interactions.

The current climate urgency has triggered an ever-growing interest for biotic photonics, that is use biological systems as inspiration or as source of biological-derived materials for technological applications. Here we will show that biogenic silica nanostructures produced by diatom microalgae can show advanced photonic properties similar to man-made slab photonic crystals. Moreover, we demonstrated that relevant properties such as the photonic bands of the structures can be trimmed postmortem via chemical functionalization. We will also present our recent results for in-vivo functionalization of the biogenic silica with different organic dyes. This strategy allows to add of emission properties in the VIS-NIR to the biogenic slab photonic crystals demonstrating that is possible to obtain functional emission photonic devices on a technologically relevant material such as silica.

The Near-Infrared I (NIR-I) region of the electromagnetic spectrum (700-950 nm) has high penetration depth and lower absorption, leading to improved fluorescence imaging for in vivo applications. We address the limitations of low quantum yield and photostability in NIR-I fluorophores by developing a new series of dyes called Au nanodyes (AuNDs). These AuNDs, formed by conjugating gold nanoparticles (nanospheres and rods) to a cyanine-based NIR fluorophore via PEG chains, aim to enhance quantum yield and photostability. Our optimized AuNDs, used alongside the IR800 NHS ester dye, demonstrate stable fluorescence lifetime (FLT) in tracking cancer cells. Additionally, we differentiate stimulated and unstimulated T cells based on FLT variations, highlighting the potential of AuNDs for T-cell-based immunotherapy studies in cancer treatment.

Alzheimer’s disease (AD) is the most common cause of dementia. Despite urgent need, early detection of AD and long- 9term monitoring of AD progression have been challenging. This is due to the limited availability of brain imaging facilities and the highly invasive procedure with the cerebrospinal fluid assay to assess the level of AD biomarkers, such as beta-amyloid (Aβ).Reliable measurements of AD biomarkers in blood samples are still difficult because of their very low abundance. Here, we develop a rapid, specific, and ultrasensitive immunoassay using plasmonic-gold nanoisland (pGOLD) chips with near-infrared fluorescence-enhanced detection for Aβ1−40 and Aβ1−42. We show step-by-step processes and results during the platform establishment, including antibody specificity and sensitivity tests, antibody pair examination, condition optimization, and procedure refinement. Finally, we demonstrate the platform performance with detection sensitivity at the subpicogram per milliliter level. This platform, therefore, has a great application potential for early detection of AD using blood samples.

Detecting unmodified DNA label-free is challenging, but Surface-Enhanced Raman Spectroscopy (SERS) and Metal-Enhanced Fluorescence (MEF) offer promising solutions. We used colloidal gold nanoparticles (AuNPs) to address reproducibility issues in SERS analysis, attaching polyA strands with a thiol group and Cy5 fluorophore to AuNPs. Binding target molecules, such as polyT aptamers, caused conformational shifts that reinstated fluorescence. We tested various lengths and concentrations of polyA and polyT, with promising results confirmed by changes in fluorescence lifetime, enabling real-time detection and quantification of DNA hybridization with ease.

In the biomedical field, the reemitted light intensity measured from the tissue depends on both scattering and absorption. In order to separate these variables, we use a physical phenomenon discovered in our lab, called the iso-path length (IPL) point. The IPL point is a specific angle around a cylindrical media, where the light intensity is not affected by the scattering and can serve for self-calibration. For a practical use of this concept, we designed an optic biosensor for measuring physiological parameters such as heart rate and oxygen saturation, in both ordinary and extreme conditions in a hypoxic chamber.

Main challenge in designing nanoparticles (NPs) as nanocarriers for topical treatment drugs is detecting NPs permeation through the skin. NPs are typically too small to be detected by regular noninvasive imaging techniques due to their size and depth. Thus, this work proposes the use of the iterative multi-plane optical properties extraction (IMOPE) technique. The technique has the capability to detect the NPs presence in different skin layers as a change of the optical. In the research, 4 variations of gel with NPs were applied on different mice which were later analyzed by the IMOPE technique and by chemical methods. The exam groups were: NPs only, full complex of NPs with drug, full complex with additional enzyme and enzyme only. The enzyme was suggested to enhance NPs penetration. Overall, the results demonstrated NPs' decreasing permeation profile across different skin layers and highlighted the enzyme's effect on enhancing NPs' penetrability.

GLUT1 is a crucial target in cancer treatment due to its overexpression in many cancer cells, which rely on increased glucose uptake for rapid growth. Given GLUT1's high affinity for glucose, this monosaccharide is a promising candidate for targeted drug delivery. Recently, mannose has also been considered due to its transport via GLUT1, though with lower affinity, and the mannose receptor, which is often overexpressed in certain cancer cells. Comparing glucose and mannose as targeting moieties can provide insights into optimizing nanoparticle design. In this study, we synthesized glucose-coated and mannose-coated liposomes and compared their uptake in cancer cells. Our results showed that glucose-coated liposomes have significantly higher uptake compared to mannose-coated ones. These findings underscore the superior potential of glucose-coated nanoparticles for targeted cancer therapy, leveraging GLUT1's natural affinity for glucose to enhance drug delivery efficiency.

Cisplatin (CPt) remains a cornerstone treatment for bladder cancer; however, its use is often limited by severe nephrotoxicity, excluding many patients with advanced disease from receiving optimal care. To address this challenge, we developed gold nanoparticles (GNPs) conjugated with CPt , engineered to minimize renal toxicity while retaining the drug’s anticancer potency. The safety and therapeutic impact of CPt-GNPs were evaluated in a bladder tumor-bearing mouse model. A single high-dose administration of CPt-GNPs resulted in tumor growth suppression and prevention of CPt-induced mortality in a mouse model of bladder cancer. Notably, CPt-GNPs did not induce kidney necrosis or weight loss, in contrast to free CPt. These findings suggest that CPt-conjugated GNPs offer a dual benefit of effective tumor control and renal protection, potentially expanding the pool of patients eligible for CPt-based therapies.

Gold nanoparticles (GNPs) are emerging as promising platforms for antibody-based cancer therapy. Their distinctive physicochemical properties allow the binding of a large amount of antibodies to a single particle, potentiating their therapeutic potential. However, there is need to elucidate the effect of common synthesis approaches on the antibody-GNP characteristics and activity. This study investigated the effects of common synthesis approaches, namely, covalent binding and physical adsorption, on the properties of antibody-coated GNPs. We found that antibody mass affected antibody binding efficiency. Moreover, covalent binding of antibodies to GNPs had superior cancer cell killing ability as compared to the adsorption method. These findings highlight the critical role of synthesis approaches for efficacy of antibody-bound GNPs for cancer therapy.

Early detection and diagnosis of cancer are crucial due to its widespread emergence, high fatality rate, and recurrence after treatment. Surface-enhanced Raman Scattering (SERS), a technique that enhances the Raman signals of molecules, has shown promise in high-sensitivity and specificity detecting and analyzing cancer biomarkers. In this study, a diatomite-based SERS active platform is fabricated and used for fast, sensitive, and multiplex detection of cancer protein biomarkers. The surface of the SERS-based immunoassay platform is modified with a mix of antibodies that are specific for HER2, PSA, and MUC4. In addition to this, Raman tags are prepared for each cancer protein. A mixture of cancer protein biomarkers in serum is incubated on the surface of a modified SERS-based immunoassay. Then the mixture of Raman tags is incubated to form a sandwich. In order to multiplex the detection of the mixture of cancer protein biomarkers, Raman mapping measurements were obtained when the sandwiches occurred. In conclusion, we developed a simple, cheap, and sensitive SERS-based immunosensor that can detect PSA, HER2, and MUC4 proteins in the serum at the same time on a single surface.

Many biological surfaces display complex micro- and nano-scale structures that serve diverse purposes, such as anti-reflective effects, structural coloration, resistance to fouling, and either promoting or preventing adhesion. These unique properties have spurred the development of numerous industrial applications. In recent years, interest in this field has grown significantly, driven by the increasingly interdisciplinary methods used to study these structured biological surfaces. The COST ACTION “PhoBioS - Understanding Interaction light-biological surfaces: possibly for new electronic materials and devices” aims to bring together scientists from various disciplines in this exciting field of research. The collaboration focuses on investigating the photonic effects that emerge from the nano- and nano-structuring of biological surfaces and exploring their potential bionic applications. By uniting experts from diverse research areas, the consortium seeks to inspire cross-disciplinary innovation, fostering an environment that supports groundbreaking discoveries and industrial advancements. This initiative leverages current scientific progress to drive exploration into the complex wo

In this paper, we introduce a novel method that employs a rolling shutter camera in conjunction with a heterodyne interferometric system to monitor blood flow and acoustic signals. This technique involves analyzing spatial-temporal changes in interferometric fringe patterns. By leveraging the rolling shutter mechanism, we can capture high-resolution temporal variations, which are crucial for detecting fast acoustic vibrations and dynamic blood flow changes. The heterodyne interferometric system enhances the signal-to-noise ratio of the measurements, allowing for high sample rate monitoring. This approach offering potential applications in medical diagnostics and biomedical research.

Non-contact diffuse reflectance spectroscopy (DRS) can measure absorption-dictating properties, including the bandgap of semiconductors. The robustness of recovering absorption by DRS depends upon the mathematical model used to link spectral absorption with diffuse reflectance, and the accuracy of predicted scattering. To enhance spectral absorption estimation of non-contact DRS, we characterize the sample scattering properties using low-coherence interferometry (LCI). The scattering profile over a 60nm bandwidth is collected in the O-band, spatial resolution of LCI is sacrificed for spectral information. The spectral information helps extrapolate Mie-scattering properties over the visible band of non-contact DRS, enhancing characterization of spectral absorption.

Communication of cancer cells with immune cells can inhibit or promote tumor proliferation. However, immune–tumor interactions in cancer tissues remain largely uncharacterized. A direct quantification of cell–cell interactions between individual immune and tumor cells can be obtained via in situ approaches, which use imaging to assess the identity and location of expressed genes. We recently developed a technology, termed expansion sequencing, which allows in situ sequencing of RNA molecules with super-resolution. Here, we show that super-resolved in situ sequencing can be used to quantify immune–tumor cell–cell interactions inside patients' biopsies, which might be utilized to predict response to immunotherapy drugs.

Hybrid electrical and optical neuroimaging systems enable a comprehensive analysis of brain activity by capturing both rapid neural dynamics and detailed spatial information about brain regions. These systems enhance brain mapping accuracy and improve our understanding of neural processes by providing complementary data from neuronal and vascular modalities. In this paper, we present a hybrid system that combines speckle contrast optical spectroscopy (SCOS) with electroencephalography (EEG). Preliminary results highlight the significant potential of this hybrid approach for Brain-Computer Interface (BCI) and neurofeedback applications.

Acute myocardial infarction is the most serious cardiovascular illness; threatening human lives for decades. Its fast diagnosis can considerably improve the patient’s prognosis as well as survival, thus a great amount of effort is directed to the development of biosensing technologies, which are able to efficiently and accurately detect the cardiac troponin biomarkers, the gold standard in detecting myocardial injury. Therefore, we developed a microfluidic plasmonic chip for the fast and accurate real-time detection of the cardiac troponin I biomarker.

We introduce a novel biosensing approach that utilizes photonic crystal-enhanced fluorescence technology integrated with a bioinspired DNA origami NanoGripper, selectively generating a fluorescent signal only upon detecting SARS-CoV-2. Photonic crystals (PC), serving as dielectric microcavities, provide substantial local field enhancement, far-field directional emission, large Purcell factors, and high quantum efficiency. These novel origami probes are coupled with a Photonic Crystal Enhanced Fluorescence Microscope, achieving a 10,000-fold signal enhancement compared to traditional single fluorophore reporters on glass substrates. Unlike surface-based ELISA assays, the capture reaction between the NanoGripper and the SARS-CoV-2 virus occurs in solution, reaching equilibrium within 10 minutes. After mixing, the mixture is pulled down to the PC surface for signal enhancement and direct counting. With virtually zero off-target signals, we achieve a limit of detection (LoD) of 100 viral genome copies per mL in human saliva, enabling ultra-high detection sensitivity.

Sutures and staples are commonly used in surgery to bond tissues together. However, their invasiveness often causes infections, leaks and other complications that pose a significant threat to the life of the patient. To avoid these complications, research has been conducted to look for alternative surgical techniques. Laser Tissue Soldering (LTS) is an emerging technology that can form strong watertight bonds and can be used as an alternative to sutures and staples. While highly promising, thermal control in laser tissue soldering is of utmost importance. Fluorescent nanothermometers that work in the biological optical windows overcome these problems. Moreover, nanoabsorbers allow for confined thermal heating. In this work we show how the fluorescence of the nanothermometers can be used in minimally invasive surgeries providing key guidance needed to achieve the desired tissue bonding with minimal surrounding thermal damage.

This research develops innovative biosensor platforms for efficient, portable, and cost-effective diagnostics at the point-of-need, integrating optical, microfluidic, and chemiluminescence technologies with CMOS image sensors. A novel CMOS image sensor-based biosensor is presented for rapid detection of microbial contamination, demonstrating high sensitivity and correlation with commercial methods. Additionally, a single-electrode electrochemiluminescence (SE-ECL) system on-CMOS is introduced for uric acid detection, showing high selectivity and reusability. A novel SE-ECL configuration for multiplexed detection of multiple analytes using color-coded luminophores is also presented, highlighting its value for complex analyses. These platforms have significant potential in medical diagnostics, environmental monitoring, and food safety.

Random lasing or lasing of a random medium that has a gain mechanism used to be called “photonic bomb”. The condition of the lasing of a random medium is an interplay among the size, gain pathlength, and scattering pathlength of the medium. Therefore, new understanding of the lasing condition or the threshold size of random lasing may provide new insights to sensing applications. By extending a new model approach to the lasing of random medium demonstrated in time-domain [Piao, 2024] to the frequency-domain, this work develops a preliminary treatment to lasing dynamics of random medium under modulated pumping for sensing.

Recently, laser-based secondary speckle patterns became an advanced technique for medical conditions diagnostics. We apply the newly developed technique to the diagnostics of the Sleep Apnea Disorder during a sleep cycle. Sleep apnea disorder is a sleep disorder characterized by breathing interruptions or shallow breaths during sleep, which can have pauses lasting from seconds to minutes, occurring multiple times per hour. The novel method of remote optical vibration reconstruction is based upon spatially and temporally coherent laser beam illumination of a back reflecting surface, its roughness generates random phase distribution that in the far field results in a self-interfering secondary speckle pattern. Our nanoscale optical technique tracks the movement of speckle patterns captured by a remote camera, which is later reconstructed into the breathing vibrational profile of a subject. The preliminary experiments were applied to dozens of subjects in various sleeping positions. The novel approach provides good preliminary results with an accuracy close to 100% of recognition and alerting of sleep apnea episodes with a duration of 10 and 20 seconds.

One of the key challenges in breast cancer is matching drugs to patients. Optical measurement of immune-tumor cell interactions in biopsies might help predict the success of immunotherapy drugs, which activate the immune system against tumor cells. I leverage Expansion Sequencing, a technology for nanoscale resolution multiplexed imaging, to generate spatial genomics maps of breast cancer biopsies. These maps reveal not only physically touching immune and tumor cells, but also if the immune cells are activated by this proximity. This imaging-based technology extracts new data from biopsies that can aid in predicting immunotherapy effectiveness.

In the Dicentrics Chromosome Assay for radiation damage detection, chromosomes fall on slides and aggregate to groups. This reduces the ability to count them. We have devised a set of algorithms that discern mildly to moderately aggregated chromosomes for our DAPI+C-Banding staining method, whose chief properties are fast application and a new contrast mechanism, where the centromeres are labelled with high contrast on the chromosomes, with a common fluorescent stain. The algorithms are adaptive. They combine binary search with measurable features in the images, to ease the constraints of a non-machine-learning code, that was overtrained for a specific image or several images. With this method we have achieved high detection ability of chromosomes and centromeres with traditional image processing algorithms.

TLD (Thermoluminescent Dosimetry) is needed to measure employee exposure and monitor patient overexposure in medical ionizing radiation procedures. It then has to be moved from the measurement location to a facility for readout by heating with hot nitrogen. In our method a laser heats the crystal, a noncontact radiometer reads the temperature and a visible detector reads the thermoluminescent emission. These are correlated and calibrated to get the dose. Very high speeds of heating can be achieved. The crystal can be repeatedly exposed and measured in-situ and in real time. Our readout can provide hospitals with a facility monitoring device for easy readout of TLD crystals.