High-resolution Thermal Mapping Research Articles

Combining bird tracking data with high-resolution thermal mapping to identify microclimate refugia

Elevated temperatures can have a range of fitness impacts, including high metabolic cost of thermoregulation, hence access to microclimate refugia may buffer individuals against exposure to high temperatures. However, studies examining the use of microclimate refugia, remain scarce. We combined high resolution microclimate modelling with GPS tracking data as a novel approach to identify the use and availability of cooler microclimate refugia (sites > 0.5 °C cooler than the surrounding landscape) at the scales experienced by individual animals. 77 little bustards (Tetrax tetrax) were tracked between 2009 and 2019. The 92,685 GPS locations obtained and their surrounding 500 m areas were characterised with hourly temperature and habitat information at 30 m × 30 m and used to determine microclimate refugia availability and use. We found that the semi-natural grassland landscapes used by little bustards have limited availability of cooler microclimate areas—fewer than 30% of the locations. The use of cooler microclimate sites by little bustards increased at higher ambient temperatures, suggesting that individuals actively utilise microclimate refugia in extreme heat conditions. Microclimate refugia availability and use were greater in areas with heterogeneous vegetation cover, and in coastal areas. This study identified the landscape characteristics that provide microclimate opportunities and shelter from extreme heat conditions. Little bustards made greater use of microclimate refugia with increasing temperatures, particularly during the breeding season, when individuals are highly site faithful. This information can help identify areas where populations might be particularly exposed to climate extremes due to a lack of microclimate refugia, and which habitat management measures may buffer populations from expected increased exposure to temperature extremes.

Printed temperature sensor array for high-resolution thermal mapping

Fully-printed temperature sensor arrays—based on a flexible substrate and featuring a high spatial-temperature resolution—are immensely advantageous across a host of disciplines. These range from healthcare, quality and environmental monitoring to emerging technologies, such as artificial skins in soft robotics. Other noteworthy applications extend to the fields of power electronics and microelectronics, particularly thermal management for multi-core processor chips. However, the scope of temperature sensors is currently hindered by costly and complex manufacturing processes. Meanwhile, printed versions are rife with challenges pertaining to array size and sensor density. In this paper, we present a passive matrix sensor design consisting of two separate silver electrodes that sandwich one layer of sensing material, composed of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). This results in appreciably high sensor densities of 100 sensor pixels per cm^2 for spatial-temperature readings, while a small array size is maintained. Thus, a major impediment to the expansive application of these sensors is efficiently resolved. To realize fast and accurate interpretation of the sensor data, a neural network (NN) is trained and employed for temperature predictions. This successfully accounts for potential crosstalk between adjacent sensors. The spatial-temperature resolution is investigated with a specially-printed silver micro-heater structure. Ultimately, a fairly high spatial temperature prediction accuracy of 1.22 °C is attained.

Robot-based mobile sensing system for high-resolution indoor temperature monitoring

Indoor environmental quality (IEQ) monitoring is an important basis of smart buildings to ensure human comfort and control energy systems. IEQ monitoring conventionally relies on a limited number of stationary sensors deployed at selected locations, which has little capacity to capture fine spatial characteristics due to the cost of infrastructure and maintenance. This paper describes a robot-based mobile sensing system for high-resolution temperature monitoring by selecting air temperature as the targeted IEQ parameter. Experiments were conducted in a classroom to test the mobile sensing performance through comparisons with the dense stationary sensor network. Furthermore, two spatio-temporal processing methods were developed to reconstruct continuous thermal maps from short- and long-term monitoring. The results indicate that the robot velocity of 0.25–0.45 m/s is better than 0.60–0.80 m/s and 0.10–0.20 m/s, and that the proposed methods are suitable for generating accurate, high-resolution thermal maps.

Nanoscale temperature of plasmonic HAMR heads by polymer imprint thermal mapping

ABSTRACT Polymer imprint thermal mapping (PITM) is a high-resolution thermal mapping technique that is especially valuable for nanoscale plasmonic devices. PITM leverages a ∼50 nm polymer film coating that crosslinks irreversibly with temperature, which records the peak temperature rise of the surface in the local, linear reduction of polymer film thickness. Using AFM to measure topography before and after heating, but not during operation, PITM sidesteps plasmonic artifacts seen in other near-field thermometries, where the probe tip disturbs and is heated directly by the near- and far-field radiation around the plasmonic device. This is notably troublesome for characterizing heat-assisted magnetic recording (HAMR) heads for next-generation hard disk drives. HAMR heads use near-field transducers (NFTs) to focus light on a magnetic media, heating a nanoscale region to its Curie temperature to enable magnetic writing. The PITM proof-of-concept was introduced at The Magnetic Recording Conference (TMRC) in 2015: here, we present a mature technique capable of benchmarking finite-element thermal simulations of nanoscale devices.

Nanoscale Thermal Mapping of HAMR Heads Using Polymer Imprint Thermal Mapping

A number of systems require high-resolution, non-perturbative thermal mapping. This need is especially apparent for heat-assisted magnetic recording (HAMR), a technology developed to increase the areal density of magnetic storage. In HAMR, plasmonic antennas are used to heat magnetic media by hundreds of degrees in a nanoscale region. Understanding the antenna's temperature is critical, but the available methods for high-resolution thermal mapping are dominated by experimental artifacts. In order to measure the temperature distributions of a plasmonic antenna without a major perturbation, a new technique, polymer imprint thermal mapping (PITM), was developed, which relies on the thermal response of a thin polymer film to report temperature. The polymer permanently cross-links upon heating, so the thermally induced height change of the polymer film is directly correlated with the sample temperature. It is experimentally shown that PITM creates thermal maps that are far superior to conventional scanning thermal microscopy. In addition, the modeled thermal distributions show remarkable agreement with the measured PITM thermal maps.

Instantaneous three-dimensional thermal structure of the South Polar Vortex of Venus

The Venus thermal radiation spectrum exhibits the signature of CO2 absorption bands. By means of inversion techniques, those bands enable the retrieval of atmospheric temperature profiles. We have analyzed VIRTIS-M-IR night-side data obtaining high-resolution thermal maps of the Venus south polar region between 55 and 85km altitudes. This analysis is specific to three Venus Express orbits where the vortex presents different dynamical configurations. The cold collar is clearly distinguishable centered at ∼62km (∼100mbar) altitude level. On average, the cold collar is more than 15K colder than the pole, but its specific temperature varies with time. In the three orbits under investigation the South Polar Vortex appears as a vertically extended hot region close to the pole and squeezed by the cold collar between altitudes 55 and 67km but spreading equatorwards at about 74km. Both the instantaneous temperature maps and their zonal averages show that the top altitude limit of the thermal signature from the vortex is at ∼80km altitude, at least on the night-side of the planet. The upper part of the atmosphere (67–85km) is more homogeneous and has long-scale horizontal temperature differences of about 25K over horizontal distances of ∼2000km. The lower part (55–67km) shows more fine-scale structure, creating the vortex morphology, with thermal differences of up to about 50K over the same altitude range and ∼500km horizontal distances. This lower part of the atmosphere is highly affected by the upper cloud deck, leading to stronger local temperature variations and larger uncertainties in the retrieval. From the temperature maps, we also study the vertical stability of different atmospheric layers for the three vortex configurations. The static stability is always positive (ST>0) in the considered altitude range (55–85km) and in the whole polar vortex. The cold collar is the most vertically stable structure at polar latitudes, while the vortex and sub-polar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex exhibit lower stability values than their surroundings. The layer between 62 and 67km resulted to be the most stable. These results are in good agreement with conclusions from previous radio occultation analyses.

Simultaneous electro‐thermal experimental analysis of RF‐MEMS switches for high microwave power handling

AbstractAn experimental setup for the characterization of electromagnetically induced heat on MEMS devices operating in high RF power regimes (> 5 W) is here proposed. The technique is based on infrared (IR) imaging of on‐probe DUT, in working conditions. The present work focuses on switches. Undoubtedly the switch represents the most emblematic and strategic component across the RF‐MEMS device portfolio. The capacitive ones can withstand more RF power with respect to DC contact (or ohmic) counterparts. Here, both serial and shunt configurations will be considered in the two working states (ON‐OFF). The approach presented here is based on a non‐intrusive real‐time IR imaging method capable to provide high resolution thermal maps and thermal transients of DUTs undertaking up to 6.3 W of CW incident power at 10 GHz. This technique represents a very powerful approach toward design optimization on the one hand and fast testing and product quality assessment against RF induced failures in production line for integrated RF MEMS and MMIC front‐end. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Hot spot detection in integrated circuits working at up to 1 GHz

Constraints on integration densities and on operating frequencies of integrated circuits have become so important that thermal phenomena can not be neglected any longer. A high resolution thermal mapping of such circuits under operation is then needed. As we show in this paper, the thermoreflectance technique, based on the reflection coefficient variation with temperature give access to the elevation of temperature produced by the circuit after the execution of benchmarks. In this paper, the frequency of the benchmark can be as high as 1 GHz and we show that using a low repetition rate of these benchmarks makes it possible to retrieve the thermal response of the circuit working at high frequency. These measurements can be very useful to adjust thermal dissipation models and to analyse failures.

Ultracompliant thermal probe array for scanning non-planar surfaces without force feedback

This paper describes an array of micromachined thermal probes for scanning thermal microscopy for which the structural design and choice of materials virtually eliminate the need for z-axis mechanical feedback in contact mode scans. The high mechanical compliance accommodates significant topographical variation in the sample surface and prevents damage to soft samples. Thin film metal bolometers are molded into tips at the end of each cantilever in the array, and are sandwiched between two layers of polyimide that serves as the structural material. The probes overhang a Si substrate on which they are fabricated. Since integrated actuators and accompanying circuitry are no longer required, the prospect of scaling from the present eight-probe version to large numbers of probes for high speed, high resolution thermal mapping of large areas with simple detection circuitry is enhanced. The scalability and performance of the eight-probe prototype are evaluated, addressing issues of speed versus resolution, and thermal and mechanical decoupling. The results demonstrate that contact mode scans can provide better than 2 µm spatial resolution at speeds greater than 200 µm s−1 and show a 6.5 bit topographical resolution over a 7 µm dynamic range. Line scans obtained with a single-shank probe suggest that there are good prospects of obtaining images showing a lateral spatial resolution of less than 50 nm.

Application of thermographic analysis for the detection of longitudinal defects in cold mills

The paper presents the work done to assess the usefulness of the thermographic analysis in the design of a detection system for longitudinal defects in coils manufactured by a tandem cold mill. The approach started with a first phase devoted to the development of a computer system for the acquisition of high resolution thermal maps of the whole strip. In the second phase the thermal maps are classified and related to the process variables.

High resolution thermal mapping of microcircuits using nematic liquid crystals

An improved method for high resolution thermal mapping is discussed. This method utilizes nematic liquid crystals and has been primarily applied to inspect microcircuits. By making use of two nematic liquid crystals in conjunction with reflected light polarizing microscopy a thermal resolution of about 0.05 K has been achieved. Resolution limits are considered in detail for heat generation occurring at some depth from the surface of the sample. In addition, a comparison is made between the commonly used cholesteric method and the present work. To demonstrate the capability of the method the thermal mapping of an LED is shown.