An Active Pixel‐Matrix Electrocaloric Device for Targeted and Differential Thermal Management

Abstract

CPU) moved into multi-core, coolers can deal with the chip as a single-site heat source for effective cooling. But the multi-core CPU is packaged as a whole, and the localized overheating site in one core can heat others up. The localized overheating site makes the thermal challenge much more difficult, and it caused more than 55% of all failures in current electronics. [5,6] As operating temperature approaches 70-80 °C, the performance of electronics will degrade by ≈10% for every 2 °C increase. [7] So, the precise cooling technology in integrated circuits has become increasingly a restrictive factor affecting the development of the electronics industry. [8][9][10] Vapor-compression refrigeration systems are bulky, complex, and difficult to scale down to meet the cooling demands of electronic chips. Existing refrigerants also have high global warming potentials, and present an environmental risk upon leakages or improper disposal. Therefore, it is urgent and vital to develop a highly efficient, environmentally friendly, compact, and portable refrigeration device to achieve precise cooling.Solid-state cooling systems, especially caloric-effect-based refrigeration such as the elasto/baro caloric effect, [11] magnetocaloric effect, [12] and electrocaloric (EC) effect, [8,9,[13][14][15] have the advantages of no compressors and conventional liquid or vapor refrigerants, environmental protection, and rapid cooling. The EC refrigeration has been praised for its high coefficient of performance (COP), simple setup, low cost, and feasibility for embedded application in compact integrated circuits. [13] Thus, they can solve the practical cooling requirements of integrated microelectronics that traditional compressor technology is difficult to address. The EC is a reversible adiabatic temperature change (ΔT) and/or isothermal entropy change (ΔS) in dielectric materials induced by an external electric field change (ΔE). [8] Although a large voltage is applied, the generated current and corresponding power consumption are still very small, because of the insulating properties of the EC materials. Therefore, EC refrigeration device exhibits a great application prospect in miniature electronics cooling.Compared to the inherent brittleness of EC multilayer ceramic capacitors, [16,17] the poly(vinylidene fluoride) (PVDF)based ferroelectric polymers have been praised for their light weight, large isothermal entropy change, flexibility, and More than 55% of electronic failures are caused by damage from localized overheating. Up to now, there is still no efficient method for targeted temperature control against localized overheating. Although some existing thermal management devices handle this issue by full coverage cooling, it generates a lot of useless energy consumption. Here, a highly efficient pixel-matrix electrocaloric (EC) cooling device is reported, which can realize a targeted and differential thermal management. The modified poly(vinylidene fluoride-tertrifluoroethylene-chlorofluoroethylene) reaches a large adiabatic te...

Self-sustaining personal all-day thermoregulatory clothing using only sunlight

“…Although an outside electric supply was previously required to power the EC device to achieve the effective thermal management reported in the literature ( 35 – 37 , 43 ), we demonstrated that the EC device can instead be powered directly on site by an integrated flexible OPV module. The integrated device shows the same outstanding performance, including the same temperature difference (Δ T ) at the same electric field (Fig.…”

“…The working mechanism of the OETC system for the cooling mode (Fig. 2B) is the same as that powered by the electric supply ( 37 ), but in our system, we power it directly by the electricity generated by the OPV module (see fig. S9 for details).…”

“…Electrostatic actuation is a simple and fast method to control the heat transport speed by adjusting the working frequency of the EC device ( 35 – 37 , 43 ). We compared the temperature span of the OETC system at different frequencies under the standard AM 1.5G (100 mW/cm 2 ) by a solar simulator (fig.…”

“…The temperature span of the EC device can be increased to improve the thermoregulation performance of our OETC system. First, for the material side, the double bond–modified P(VDF-TrFE-CFE) materials could provide a larger temperature change of 7.8 K at 118 MV/m ( 37 ). Second, the device could be optimized by using a cascade device to increase the temperature span of 4.8 K (double-deck) and 8.7 K (four-layer cascade) ( 38 , 45 ).…”

High cooling performance in a double-loop electrocaloric heat pump

“…( C ) Δ T span as a function of EC temperature change (Δ T EC ) of different EC-based prototypes. BTO, BaTiO 3 ( 29 – 32 ); PVDF, poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] ( 33 ) and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] ( 12 , 34 , 35 ); BST@PVDF, Ba x Sr 1– x TiO 3 nanoparticles-filled P(VDF-TrFE-CFE) ( 36 , 37 ); PMN-PT, 0.9Pb(Mg 1/3 Nb 2/3 )O 3 –0.1PbTiO 3 ( 38 ); PST, PbSc 0.5 Ta 0.5 O 3 ( 15 , 39 , 40 ).…”