Studying the development of neural circuits in rodent models requires surgical access to the neonatal brain. Since commercially available stereotaxic and anesthetic equipment is designed for use in adults, reliable targeting of brain structures in such young animals can be challenging. Hypothermic cooling (cryoanesthesia) has been used as a preferred anesthesia approach in neonates. This commonly involves submerging neonates in ice, an approach that is poorly controllable. We have developed an affordable, simple to construct device - CryoPup - that allows for fast and robust cryoanesthesia of rodent pups. CryoPup consists of a microcontroller controlling a Peltier element and a heat exchanger. It is capable of both cooling and heating, thereby also functioning as a heating pad during recovery. Importantly, it has been designed for size compatibility with common stereotaxic frames. We validate CryoPup in neonatal mice, demonstrating that it allows for rapid, reliable and safe cryoanesthesia and subsequent recovery. This open-source device will facilitate future studies into the development of neural circuits in the postnatal brain.

Thermoelectric coolers (TECs) can reach temperatures below that obtained with a steady-state current by applying an electrical current pulse which enables a transitory state in a Peltier device. This effect is known as supercooling. In this paper, we study characteristics parameters, such as the minimum cooling temperature and spatial temperature profile, in a TEC operated under current pulses and a cooling load ( Q c ) . Numerical analysis for a one-dimensional thermoelectric model of the cooling system is developed, and a novel MATLAB programming code is proposed for the transient state based on finite element analysis. We also investigate the influence of the thermoelement\'s length upon the cooling mechanism. A new parameter called the \"characteristic cooling length\" is proposed to describe the length in which the minimum cooling temperature occurs along the elements of a TEM. Results show the transient temperature profiles along the elements of the semiconductor P-type element, and a \"characteristic cooling length\" is characterized. We also propose a general principle, and the lowest cooling temperature values are obtained for a semiconductor\'s small length and variable pulse cooling load under current pulse operation. The present study will serve as guidance for the geometric design of TECs under current pulse operations.

In this work, a low-cost, open-source and replicable system prototype for thermal analysis of low-cost Micro Electro-Mechanical Systems (MEMS) Inertial Measurement Unit (IMU) sensors in tilt measurement perspective is presented and tested. The system is formed of a 3D printed frame, a thermal cell consisting in a Peltier element mounted over a heat sink, and a control and power system. The frame is designed to allow the independent biaxial tilting of the thermal cell through two servomotors. The control board is formed by an Arduino® and a self-made board including a power drive for controlling the thermal unit and servomotors. We tested the chamber analyzing the behavior of multiple MEMS IMU onboard accelerometers suitable for measuring tilt. Our results underline the variability of the thermal behavior of the sensors, also for different sensor boards of the same model, and consequently the need for the adoption of a thermal compensation strategy based on thermal analysis results. These data suggesting the need for the analysis of the thermal behavior of MEMS-based sensors, indicate the potential of our system in making low-cost sensors suitable in medium-to-high precision monitoring applications.

Enabling temperature dependent experiments in Atomic Force Microscopy is of great interest to study materials and surface properties at the nanoscale. By studying Curie temperature of multiferroic materials, temperature dependent phase transitions on crystalline structures or resistive switching phenomena are only a few examples of applications. We present an equipment capable of cooling samples using a thermoelectric cooling stage down to -61.4 °C in a 15 × 15 mm2 sample plate. The equipment uses a four-unit thermoelectric stack to achieve maximum temperature range, with low electrical and mechanical noise. The equipment is installed into a Keysight 5500LS Atomic Force Microscopy maintaining its compatibility with all Electrical and Mechanical modes of operation. We study the contribution of the liquid cooling pump vibration into the cantilever static deflection noise and the temperature dependence of the cantilever deflection. A La0.7Sr0.3MnO3-y thin film sample is used to demonstrate the performance of the equipment and its usability by analyzing the resistive switching phenomena associated with this oxide perovskite.

The influence of nanostructuring and quantum confinement on the thermoelectric properties of materials has been extensively studied. While this has made possible multiple breakthroughs in the achievable figure of merit, classical confinement, and its effect on the local Seebeck coefficient has mostly been neglected, as has the Peltier effect in general due to the complexity of measuring small temperature gradients locally. Here we report that reducing the width of a graphene channel to 100 nm changes the Seebeck coefficient by orders of magnitude. Using a scanning thermal microscope allows us to probe the local temperature of electrically contacted graphene two-terminal devices or to locally heat the sample. We show that constrictions in mono- and bilayer graphene facilitate a spatially correlated gradient in the Seebeck and Peltier coefficient, as evidenced by the pronounced thermovoltage Vth and heating/cooling response Δ TPeltier, respectively. This geometry dependent effect, which has not been reported previously in 2D materials, has important implications for measurements of patterned nanostructures in graphene and points to novel solutions for effective thermal management in electronic graphene devices or concepts for single material thermocouples.

This study presents a novel, thermoelectric cryotherapy cap that aims to provide effective and controlled scalp cooling to prevent hair loss for chemotherapy patients. The cap\'s design consists of multiple thermoelectric coolers (TECs) evenly spaced and bonded to a soft thermal interface material, tightly fitted to a patient\'s head. A numerical model is developed to assess the performance of alternative cap designs in relation to their ability to achieve hair follicle hypothermia. Under ideal conditions, 26.5 W of heat removal from the scalp is required to achieve the clinically-significant follicle temperature target of 22 °C. Temperature maps of the subcutaneous tissue are generated to visualise the development of hypothermic follicles, and thereby assess the effectiveness of the cap design. Transient studies show that cooling to the therapeutic temperature can be achieved within 40 min. To avoid the possibility of cold-induced tissue damage, individual thermoelectric cooling modules should not be operated at a cooling flux beyond approximately 3175 W/m2. This may be achieved with 38 modules evenly spaced in a checkerboard arrangement, each providing 0.7 W of cooling to the scalp.

Thermoelectric generators (TEGs) are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius) temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized battery-free sensor modules powered by TEGs. In this article, we present the design of an ambient-powered wireless bolt for high-end electro-mechanical systems. The bolt is equipped with a temperature sensor and a low power RF chip powered from a TEG. A DC-DC converter interfacing the TEG with the RF chip is used to step-up the low TEG voltage. The work includes the characterizations of different TEGs and DC-DC converters to determine the optimal design based on the amount of power that can be generated from a TEG under different loads and at temperature gradients typical of industrial environments. A prototype system was implemented and the power consumption of this system under different conditions was also measured. Results demonstrate that the power generated by the TEG at very low temperature gradients is sufficient to guarantee continuous wireless monitoring of the critical fasteners in critical systems such as avionics, motorsport and aerospace.

Rapid focal cooling is an attractive nondestructive strategy to control and possibly prevent focal seizures. However, the temperature threshold necessary to abort seizures in primates is still unknown. Here, we explored this issue in a primate epilepsy model and observed the effect of rapid cooling on different electroencephalogram frequency bands, aiming at providing necessary experimental data for future clinical translational studies and exploring the mechanism of focal cooling in terminating seizures. We induced focal neocortical seizures using microinjection of 4-aminopyridine into premotor cortex in five anesthetized cynomolgus monkeys. The rapid focal cooling was implemented by using a thermoelectric (Peltier) device. As a result, the average durations of seizures and interictal intervals before cooling were 94.3±4.0s and 62.3±6.9s, respectively. When the cortex was cooled to 20°C or 18°C, there was no effect on seizure duration (109.4±30.0s, 91.3±19.3s) or interictal duration (99.4±26.8s, 83.2±11.5s, P>0.05). But when the cortex was cooled to 16°C, the seizure duration was reduced to 54.1±4.9s and the interictal duration was extended to 175.0±16.7s (P<0.05). Electroencephalogram spectral analysis showed that the power of delta, alpha, beta, gamma and ripples bands in seizures were significantly reduced at 20°C and 18°C. At 16°C, the power of theta band in seizures was also significantly reduced along with the other bands. Our data reveal that the temperature threshold in rapid focal cooling required to significantly shorten neocortical seizures in nonhuman primates is 16°C, and inhibition of electroencephalogram broadband spectrum power, especially power of theta band, may be the underlying mechanism to control seizures.

A new active safety concept that engages the driver\'s psychosensory pain-processing mechanism to automatically trigger vigilance enhancement on-demand was proposed in Chang (2012). This concept is based on the hypothesis that a human\'s pain threshold will decline as he or she becomes drowsy, consequently triggering the vigilance enhancer. The objective of this pilot study was to develop methods to test this hypothesis, the results of which could lead to further refinement of the hypothesis and methods, with the ultimate goal of developing new active safety concepts that exploit the driver\'s endogenous psychosensory pain-processing mechanisms. Preliminary results from a pilot study designed to test this hypothesis were presented in Chang (2016). This article presents further analysis of the pilot study data.
Perceived pain responses of six healthy male participants were measured when their vigilance would be under stress. A time-varying thermal grill illusion (TGI) of pain was created using a custom steering wheel with an array of Peltier elements held in the participant\'s palm. The participant\'s pain responses to the TGI stimulus were recorded while changes in his vigilance were monitored using pre- and post-session Psychomotor Vigilance Task (PVT) tests, in-session Percent Eyelid Closure (PERCLOS), and subjective Karolinska Sleepiness Scale (KSS) ratings. The probability of pain response versus TGI temperature stimulus and vigilance measures were then estimated using logistic regression analysis.
The results indicate that the probability of pain response is correlated with the temperature stimuli and the vigilance state. The pain threshold tends to move up or down versus KSS depending on the participant for high-vigilance conditions, but tends to increase when the participant becomes increasing drowsy in low-vigilance conditions. These results were statistically significant for four of the six study participants.
This limited pilot study observed that one\'s pain threshold may or may not initially decrease as originally hypothesized depending on the participant, but then increases as one becomes drowsier. While not definitive, the methods and results of this study may help to refine our hypotheses and design future studies in pursuit of detector-free on-demand driver vigilance enhancement that exploits our body\'s endogenous alert mechanism.

Capillary electrophoresis has been used to demonstrate that individual molecules of a given enzyme support different catalytic rates. In order to determine how rate varies with temperature, and determine activation energies for individual β-galactosidase molecules, a 12-channel Peltier array temperature control device was constructed where the temperature of each cell was separately controlled. This array was used to control the temperature of the central 30 cm of a 50 cm long capillary, producing a temperature gradient along its length. Continuous flow single β-galactosidase molecule assays were performed allowing measurement of the catalytic rates at different temperatures. Arrhenius plots were produced and the distribution of activation energies for individual β-galactosidase molecules was found to be 56 ± 10 kJ/mol with a range of 34-72 kJ/mol.