Cooling Performance Prediction of Particle-Based Radiative Cooling Film Considering Particle Size Distribution.

Here, we present a novel protocol concept for quantifying the cooling performance of particle-based radiative cooling (PBRC). PBRC, known for its high flexibility and scalability, emerges as a promising method for practical applications. The cooling power, one of the cooling performance indexes, is the typical quantitative performance index, representing its cooling capability at the surface. One of the primary obstacles to predicting cooling power is the difficulty of simulating the non-uniform size and shape of micro-nanoparticles in the PBRC film. The present work aims to develop an accurate protocol for predicting the cooling power of PBRC film using image processing and regression analysis techniques. Specifically, the protocol considers the particle size distribution through circle object detection on SEM images and determines the probability density function based on a chi-square test. To validate the proposed protocol, a PBRC structure with PDMS/Al2O3 micro-nanoparticles is fabricated, and the proposed protocol precisely predicts the measured cooling power with a 7.8% error. Through this validation, the proposed protocol proves its potential and reliability for the design of PBRC.

AFM-thermoreflectance for simultaneous measurements of the topography and temperature.

To understand the thermal failure mechanisms of electronic devices, it is essential to measure the temperature and characterize the thermal properties of individual nanometer-scale transistors in electronic devices. Previously, scanning thermal microscopy (SThM) has been used to measure the local temperature with nanometer-scale spatial resolutions using a probe with a built-in temperature sensor. However, this type of temperature measurement requires additional equipment to process the temperature-sensing signals and expensive temperature-sensor-integrated probes fabricated by complicated MEMS processes. Here, we present a novel technique which enables the simultaneous measurement of the temperature and topography of nanostructures only with a conventional atomic force microscope (AFM) of the type commonly used for topography measurements and without any modifications of the probe and extra accessories for data acquisition. The underlying principle of the proposed technique is that the local temperature of a specimen is estimated quantitatively from the thermoreflectance of a bare silicon AFM probe that is in contact with a specimen. The temperature obtained by our technique is found to be consistent with a result obtained by SThM measurements.