Implantation Temperature Research Articles

Development of an implantable sensor system for in vivo strain, temperature, and pH monitoring: comparative evaluation of titanium and resorbable magnesium plates

Biodegradable magnesium is a highly desired material for fracture fixation implants because of its good mechanical properties and ability to completely dissolve in the body over time, eliminating the need for a secondary surgery to remove the implant. Despite extensive research on these materials, there remains a dearth of information regarding critical factors that affect implant performance in clinical applications, such as the in vivo pH and mechanical loading conditions. We developed a measurement system with implantable strain, temperature, pH and motion sensors to characterize magnesium and titanium plates, fixating bilateral zygomatic arch osteotomies in three Swiss alpine sheep for eight weeks. pH 1–2 mm above titanium plates was 6.6 ± 0.4, while for magnesium plates it was slightly elevated to 7.4 ± 0.8. Strains on magnesium plates were higher than on titanium plates, possibly due to the lower Young's modulus of magnesium. One magnesium plate experienced excessive loading, which led to plate failure within 31 h. This is, to our knowledge, the first in vivo strain, temperature, and pH data recorded for magnesium implants used for fracture fixation. These results provide insight into magnesium degradation and its influence on the in vivo environment, and may help to improve material and implant design for future clinical applications.

Dynamic annealing assisted near-surface structural and bond stabilization in high-temperature low-energy N2+ implanted diamond.

Nitrogen-rich ultra-thin (1-2nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C-N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500-600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented.

Analysis of Lattice Damage in 4H-SiC Epiwafers Implanted with High Energy Al Ions at Elevated Temperatures

4H-SiC wafers with 12 µm epilayers were blanket implanted to a depth of 12 µm with 5 x 1016 cm-3 Al ions via Tandem Van de Graaff accelerator located at Brookhaven National Laboratory with energy range of 13.8 to 65.7 MeV at room temperature, 300 °C and 600 °C. High resolution X-ray diffraction measurements reveal the implanted layers are characterized by tensile strains. However, the dynamic annealing process reduces the level of tensile strains as the temperature of implantation is increased. Analysis indicates that the implant temperature of 600 °C is not sufficient to minimize lattice damage due to implantation and a higher implantation temperature will be required. This preliminary experiment will guide the optimization of implantation conditions for fabricating superjunction devices.

Efficient Fabrication of High‐Density Ensembles of Color Centers via Ion Implantation on a Hot Diamond Substrate

AbstractNitrogen‐vacancy (NV) centers in diamonds are one of the most promising systems for quantum technologies, including quantum metrology and sensing. A promising strategy for the achievement of high sensitivity to external fields relies on the exploitation of large ensembles of NV centers, whose fabrication by ion implantation is upper limited by the amount of radiation damage introduced in the diamond lattice. In this work an approach is demonstrated to increase the density of NV centers upon the high‐fluence implantation of MeV N2+ ions on a hot target substrate (>550 °C). The results show that with respect to room‐temperature implantation, the high‐temperature process increases the vacancy density threshold required for the irreversible conversion of diamond to a graphitic phase, thus enabling to achieve higher density ensembles. Furthermore, the formation efficiency of color centers is investigated on diamond substrates implanted at varying temperatures with MeV N2+ and Mg+ ions revealing that the formation efficiency of both NV centers and magnesium‐vacancy (MgV) centers increases with the implantation temperature.

Microstructural modifications induced by He implantation at elevated temperature in AlN

The elastic strain and damage build-ups induced by 50 keV He implantations at elevated temperature in (0001)AlN were studied using a combination of X-ray diffraction, transmission electron microscopy and elastic recoil detection analysis experiments. No long-range migration of He atoms occurs up to 700°C. The point defect recombination is found to be enhanced with the increase of implantation temperature. When He concentration exceeds a determined temperature-dependent threshold, the stabilization of vacancies through the formation of He-vacancy clusters of critical size strongly enhances the interstitial concentration and elastic strain in proportion with the local He concentration. Above this threshold, for a critical He concentration that decreases from several at% at room temperature to a few tenths of at% at 700°C, bubbles form and induce a strong increase of disorder. Specific features observed at 700°C, including the systematic superimposition of bubble clusters with basal stacking faults, suggest the triggering between 550 and 700°C of a mechanism promoting disorder, which is discussed.

Microstructure and Unusual Ferromagnetism of Epitaxial SnO2 Films Heavily Implanted with Co Ions

In this work, we have studied the microstructure and unusual ferromagnetic behavior in epitaxial tin dioxide (SnO2) films implanted with 40 keV Co+ ions to a high fluence of 1.0 × 1017 ions/cm2 at room or elevated substrate temperatures. The aim was to comprehensively understand the interplay between cobalt implant distribution, crystal defects (such as oxygen vacancies), and magnetic properties of Co-implanted SnO2 films, which have potential applications in spintronics. We have utilized scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), differential thermomagnetic analysis (DTMA), and ferromagnetic resonance (FMR) to investigate Co-implanted epitaxial SnO2 films. The comprehensive experimental investigation shows that the Co ion implantation with high cobalt concentration induces significant changes in the microstructure of SnO2 films, leading to the appearance of ferromagnetism with the Curie temperature significantly above the room temperature. We also established a strong influence of implantation temperature and subsequent high-temperature annealing in air or under vacuum on the magnetic properties of Co-implanted SnO2 films. In addition, we report a strong chemical effect of ethanol on the FMR spectra. The obtained results are discussed within the model of two magnetic layers, with different concentrations and valence states of the implanted cobalt, and with a high content of oxygen vacancies.

Thermal transfer rate is slower in bigger fish: How does body size affect response time of small, implantable temperature recording tags?

AbstractThe recent miniaturisation of implantable temperature recording tags has made measuring the water temperatures fish experience in the wild possible, but there may be a body size‐dependent delay in implanted tag response time to changes in external temperature. To determine whether fish body size affects the response rate of implanted temperature tags, we implanted 20 Salvelinus fontinalis (127–228 mm fork length (FL), 15.1–120.4 g) with temperature recording tags and subjected them to rapid temperature changes (±8°C in less than 2 seconds) in the laboratory. We found that thermal transfer rates, and the lag in temperature tag response rate, was positively correlated with fish size, but the direction of temperature change (colder or warmer) had no significant effect. In fish exposed to a slower rate of temperature change (2°C h−1) implanted tags did not show a response lag. Understanding the limitations of this important technology is crucial to determining the utility of the data it produces and its ability to accurately measure fish thermal experience in the wild.

Study of the effect of implantation temperature on the migration behaviour of Xe implanted into glassy carbon.

The effect of implantation temperature on the migration behaviour of xenon (Xe) implanted into glassy carbon and the effect of annealing on radiation damage retained by ion implantation were investigated. Glassy carbon substrates were implanted with 320keV Xe+ to a fluence of 2×1016cm-2. The implantation process was performed at room temperature (RT) and 100°C Some of the as-implanted samples were isochronally annealed in vacuum at temperatures ranging from 300°C to 700°C in steps of 100°C for 10h. The as-implanted and annealed samples were characterized using Rutherford backscattering spectrometry (RBS) and Raman spectroscopy. The RT implanted depth profiles indicated that the migration of Xe towards the surface of glassy carbon was accompanied by a loss of Xe ions. The samples implanted at 100°C indicated no diffusion or loss of Xe after annealing at 300°C. However, annealing at temperatures ranging from 400°C to 700°C resulted in a slight shift in the Xe profile tail-end towards the bulk of glassy carbon. The diffusion coefficients (D) in the temperature range of 300°C-700°C for the RT and 100°C implanted samples, activation energies (Ea), and pre-exponential factors (Do), were extracted. The values of D ranged from (9.72±0.48)×10-21 to (1.87±0.09)×10-20m2/s with an activation energy of (6.25±0.31)×10-5eV for RT implanted samples, and the samples implanted at 100°C, D ranged from (3.85±0.19)×10-21 to (6.96±0.34)×10-20m2/s with activation energy of (4.10±0.02)×10-5eV. The Raman analysis revealed that implantation at the RT amorphised the glassy carbon structure while the samples implanted at 100°C showed mild damage compared to RT implantation. Annealing of the RT-implanted sample resulted in some recovery of the damaged region as a function of increasing annealing temperature.

Miniaturized implantable temperature sensors for the long-term monitoring of chronic intestinal inflammation.

Diagnosing and monitoring inflammatory bowel diseases, such as Crohn's disease, involves the use of endoscopic imaging, biopsies and serology. These infrequent tests cannot, however, identify sudden onsets and severe flare-ups to facilitate early intervention. Hence, about 70% of patients with Crohn's disease require surgical intestinal resections in their lifetime. Here we report wireless, miniaturized and implantable temperature sensors for the real-time chronic monitoring of disease progression, which we tested for nearly 4 months in a mouse model of Crohn's-disease-like ileitis. Local measurements of intestinal temperature via intraperitoneally implanted sensors held in place against abdominal muscular tissue via two sutures showed the development of ultradian rhythms at approximately 5 weeks before the visual emergence of inflammatory skip lesions. The ultradian rhythms showed correlations with variations in the concentrations of stress hormones and inflammatory cytokines in blood. Decreasing average temperatures over the span of approximately 23 weeks were accompanied by an increasing percentage of inflammatory species in ileal lesions. These miniaturized temperature sensors may aid the early treatment of inflammatory bowel diseases upon the detection of episodic flare-ups.

Inverse dynamic defect annealing in ZnO

Radiation tolerance of semiconductors depends on the dynamic defect annealing efficiency during irradiation. Consequently, it matters at what temperature one keeps the sample during irradiation, so that elevated temperatures typically result in lower remaining disorder. In the present work, we observed an opposite trend for the nitrogen ion implants into zinc oxide. Combining ion channeling technique, x-ray diffraction, and photoluminescence spectroscopy, we demonstrate that the interaction of nitrogen with radiation defects promotes an inverse dynamic annealing process, so that the increase in irradiation temperature leads to a more efficient defect formation. As a result, the residual radiation disorder is maximized at 650 °C and this state is characterized by the appearance of prominent optical signatures associated with zinc interstitials and strongly reduced strain accumulation as compared to the samples implanted at lower temperatures. However, for higher implantation temperatures, the impact of the inverse annealing decreases correlating with the surface degradation and loss of nitrogen.

The influence of helium-induced defects on the migration of strontium implanted into SiC above critical amorphization temperature

The presence of radiation-induced defects and the high temperature of implantation are breeding grounds for helium (He) to accumulate and form He-induced defects (bubbles, blisters, craters, and cavities) in silicon carbide (SiC). In this work, the influence of He-induced defects on the migration of strontium (Sr) implanted into SiC was investigated. Sr-ions of 360 keV were implanted into polycrystalline SiC to a fluence of 2 × 1016 Sr-ions/cm2 at 600°C (Sr-SiC). Some of the Sr-SiC samples were then co-implanted with He-ions of 21.5 keV to a fluence of 1 × 1017 He-ions/cm2 at 350°C (Sr + He-SiC). The Sr-SiC and Sr + He-SiC samples were annealed for 5 h at 1,000°C. The as-implanted and annealed samples were characterized by Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and Rutherford backscattered spectrometry (RBS). Implantation of Sr retained some defects in SiC, while co-implantation of He resulted in the formation of He-bubbles, blisters, and craters (exfoliated blisters). Blisters close to the critical height and size were the first to exfoliate after annealing. He-bubbles grew larger after annealing owing to the capture of more vacancies. In the co-implanted samples, Sr was located in three regions: the crystalline region (near the surface), the bubble region (where the projected range of Sr was located), and the damage region toward the bulk. Annealing the Sr + He-SiC caused the migration of Sr towards the bulk, while no migration was observed in the Sr-SiC samples. The migration was governed by “vacancy migration driven by strain fileds.”

Implantable biosensor tracks temperature to detect early transplant rejection in rats.

Implantable biosensor tracks temperature to detect early transplant rejection in rats.

Current state of the art and future directions for implantable sensors in medical technology: Clinical needs and engineering challenges.

Implantable sensors have revolutionized the way we monitor biophysical and biochemical parameters by enabling real-time closed-loop intervention or therapy. These technologies align with the new era of healthcare known as healthcare 5.0, which encompasses smart disease control and detection, virtual care, intelligent health management, smart monitoring, and decision-making. This review explores the diverse biomedical applications of implantable temperature, mechanical, electrophysiological, optical, and electrochemical sensors. We delve into the engineering principles that serve as the foundation for their development. We also address the challenges faced by researchers and designers in bridging the gap between implantable sensor research and their clinical adoption by emphasizing the importance of careful consideration of clinical requirements and engineering challenges. We highlight the need for future research to explore issues such as long-term performance, biocompatibility, and power sources, as well as the potential for implantable sensors to transform healthcare across multiple disciplines. It is evident that implantable sensors have immense potential in the field of medical technology. However, the gap between research and clinical adoption remains wide, and there are still major obstacles to overcome before they can become a widely adopted part of medical practice.

Temperature sensing of the brain enabled by directly inscribed Bragg gratings in CYTOP polymer optical fiber implants

Brain temperature is a vital physiological parameter that has a great effect on metabolic processes, enzymatic activity, neurotransmitter function, blood flow regulation, neuroprotection, and cognitive performance. In this framework, the development of accurate and reliable brain temperature measurement tools is crucial in brain-related treatment and research, such as neurosurgery, therapeutic hypothermia, and the understanding of brain function and pathologies. Here, we developed the first large-core flexible low optical loss CYTOP polymer optical fiber (POF)-based brain temperature probe operating in the telecommunication spectral range. The temperature measurements were achieved by detecting the reflected spectrum from a fiber Bragg grating (FBG) directly inscribed at the tip of the POF using femtosecond pulses. A fluorinated ethylene propylene (FEP) tube was thermally drawn and used as a sleeve around the FBG structure to eliminate the cross-sensitivity with humidity and microstrain perturbations. The assembled POF implant has a sensitivity of 14.3 pm/°C. The local temperature of the cerebral cortex, corpus callosum, and striatum in a rat brain was measured in vivo. The results indicate that the deep brain regions have higher temperature than the top cortical ones with a relatively linear relationship between the brain structure depth and its temperature. In addition, the rectal body core temperature was detected in parallel with the brain temperature measurement to further validate the developed device. We believe that the presented CYTOP POF-based implantable temperature probe opens the way towards the development of flexible and stable tools for accurate brain temperature recording where large-core fiber-based neural devices are required.

Grain boundary softening from stress assisted helium cavity coalescence in ultrafine-grained tungsten

The formation of helium cavities in coarse-grained materials produces hardening proportional to the number density and size of the cavities and due to the interaction of dislocations with intragranular helium defects. In nanostructured metals containing a high density of interfacial sinks, preferential cavity formation in the grain boundaries instead produces softening that is often attributed to enhanced interfacial plasticity. Employing two grades of ultrafine-grained tungsten, we explore this effect using targeted implantation studies to map cavity evolution as a function of the irradiation conditions and quantify its impact on the mechanical response through nanoindentation. Softening is reported at implantation temperatures above the threshold for preferential grain boundary cavity formation but at a sufficiently low fluence prior to the growth of intragranular cavities. Collective changes in the mean cavity size, density, and morphology beneath a residual impression on an implanted surface indicate that cavity coalescence accompanied the reduction in hardness. Complementary atomistic simulations demonstrate that, in tungsten grain structures exhibiting softening, grain boundary bubble coalescence is driven by stress concentrations that further act to localize strain in the grain boundaries through cooperative deformation processes involving local atomic shuffling and sliding, dislocation emission, and even the nucleation of unstable twinning events.

The Process and Mechanism of Preparing Nanoporous Silicon: Helium Ion Implantation.

Ion implantation is an effective way to control performance in semiconductor technology. In this paper, the fabrication of 1~5 nm porous silicon by helium ion implantation was systemically studied, and the growth mechanism and regulation mechanism of helium bubbles in monocrystalline silicon at low temperatures were revealed. In this work, 100 keV He ions (1~7.5 × 1016 ions/cm2) were implanted into monocrystalline silicon at 115 °C~220 °C. There were three distinct stages in the growth of helium bubbles, showing different mechanisms of helium bubble formation. The minimum average diameter of a helium bubble is approximately 2.3 nm, and the maximum number density of the helium bubble is 4.2 × 1023 m-3 at 175 °C. The porous structure may not be obtained at injection temperatures below 115 °C or injection doses below 2.5 × 1016 ions/cm2. In the process, both the ion implantation temperature and ion implantation dose affect the growth of helium bubbles in monocrystalline silicon. Our findings suggest an effective approach to the fabrication of 1~5 nm nanoporous silicon, challenging the classic view of the relationship between process temperature or dose and pore size of porous silicon, and some new theories are summarized.

Thermogenic Phenotyping in Mice.

Thermogenesis mediated by brown adipose tissue (BAT) and brown-like fat plays an important role in regulating metabolic homeostasis in mammals. Accurate measurement of metabolic responses to brown fat activation, including heat generation and increased energy expenditure is essential for characterizing thermogenic phenotypes in preclinical studies. Here, we describe two methods for assessing thermogenic phenotypes in mice under non-basal states. First, we describe a protocol for measuring body temperature in cold-treated mice using implantable temperature transponders, which allow for continuous monitoring of body temperature. Second, we describe a method for using indirect calorimetry to measure β3-adrenergic agonist-stimulated changes in oxygen consumption, a proxy for thermogenic fat activation.

Insights into the effects of Al-ion implantation temperature on material properties of 4H-SiC

In this study, Al implantation in 4H-SiC at the dose of 1 × 1014 cm−2 was investigated. The impacts of implantation temperature on the lattice quality, microstructure, surface composition, and band structure were all studied experimentally and theoretically. Atomic force microscope (AFM) images showed the difference in surface morphology between high-temperature and low-temperature implantation. Transmission electron microscopy (TEM) characterization indicated the lattice damage induced by implantation was recovered after the post-annealing at 1750 °C, except for the samples implanted at room temperature. X-ray photoelectron spectroscopy (XPS) analysis suggested an oxidation effect during and after the implantation process, and it was more serious at lower implantation temperatures. As the implantation temperature incremented, the ratio of Si-C composition with high binding energy increased, the element valence became closer to that of ideal Al-doped 4H-SiC calculated by density functional theory (DFT); and the Fermi level shifted toward the valence band maximum (VBM), demonstrating the formation of efficient p-type doping. A more obvious asymmetric broadening in Raman spectroscopy was observed at higher implantation temperature. The theoretically obtained band structures and bond lengths from DFT calculations corroborated the experimental results, providing physical insights into the possible effect mechanism. In sum, correlations between the implantation process, external material properties, and internal crystal structure were recorded, paving the way for further research and future applications.

Thermal expansion of plasma-exposed tungsten

We report results from a systematic analysis of thermal expansion of plasma-exposed tungsten based on molecular-dynamics simulations using models of tungsten with distributions of helium (He) bubbles in the tungsten matrix. We distinguish between two approaches of filling the bubbles with He, where the amount of He in the bubble can or cannot vary with temperature. In the former case, the thermal expansion coefficient decreases monotonically with the porosity and He content of the tungsten matrix, while in the latter case, the thermal expansivity increases monotonically with increasing porosity and He content. The latter condition, where the He content in the bubble is determined at the implantation temperature and remains constant with varying temperature in the tungsten matrix, is consistent with He species transport in tungsten used as a plasma-facing component (PFC) in nuclear fusion reactors and implies the development of biaxial compressive thermal strains in the PFC material that contribute to accelerating the growth of a nanostructure on PFC tungsten surfaces. Our analysis advances the fundamental understanding of thermal expansion in PFC tungsten and contributes to the development of a thermophysical property database for properly incorporating effects of realistic heat loads into modeling the dynamical response of PFC tungsten under fusion reactor operating conditions.

PSIV-A-3 Body Temperature Monitoring Using Subcutaneously and Vaginal Sensors in Grazing Cows

Abstract Body temperature is an indicator of animal health and can be used to detect harmful physiological events in advance of clinical symptoms. Traditionally, body temperature in cattle is determined with a rectal thermometer and requires the animal to be restrained. Although systems to automatically monitor cattle health in confinement operations exist, assessing the real-time temperature of grazing cows is not common. Our object was to demonstrate an integrated sensor network for monitoring pastured cattle body temperature in comparison with temperature measured by a vaginal logger. The integrated sensor network (Mahindra & Mahindra; Mumbai, India) communicates with the data obtained from a subcutaneous temperature sensor (EmbediVet, Livestock Labs Inc.; Pittsburg, PA) to a cloud-based data storage platform. The vaginal temperature was measured by an implantable temperature logger (Micro-T 16-bit; Star Oddi, Iceland). Vaginal devices were inserted into the vagina using a controlled internal drug release (CIDR) cleaned of progesterone. The subcutaneous temperature sensors were surgically implanted through a 2cm vertical incision in the neck. Data from the implantable sensor were transmitted via Bluetooth communication to a solar-powered base station. The subcutaneous sensors and vaginal loggers were deployed on 10 grazing cattle over a period of 6 months. Data from only 4 subcutaneous sensors consistently reported data. Temperature values measured by the subcutaneous sensors had no statistical relationship (P=0.595) with body temperature measured by the vaginal temperature loggers. However, the subcutaneous sensors were able to detect changes in body temperature over time within-animal, indicating that errors in predicting temperature were more likely due to frameshift issues than an inability to track true temperature. Further improvements in data-processing and higher sample size are needed to maximize the usability of this sensor network for monitoring cattle body temperature.