LEGO® Block Structures as a Sub-Kelvin Thermal Insulator

Area of Science:

• Materials Science
• Low-Temperature Physics
• Thermal Engineering

Background:

• Traditional insulating materials often face limitations in performance or cost for specific low-temperature applications.
• The need for effective thermal isolation is critical in sensitive scientific experiments, particularly those conducted in dilution refrigerators.

Purpose of the Study:

• To measure and characterize the thermal conductance of Acrylonitrile Butadiene Styrene (ABS) structures, commonly known as LEGO® blocks.
• To evaluate the potential of LEGO® blocks as a cost-effective and high-performance thermal insulator in the millikelvin to Kelvin temperature range.
• To compare the thermal performance of ABS/void composite materials with established bulk insulator materials.

Main Methods:

• Experimental measurement of thermal conductance using a custom setup within a dilution refrigerator.
• Characterization of the material's thermal conductivity (κ) as a function of temperature (T) in the range of 70 mK to 1.8 K.
• Analysis of the power law governing thermal conductivity: κ = (8.7 ± 0.3) × 10^-5 T^1.75±0.02 WK^-1 m^-1.

Main Results:

• The thermal conductivity of the ABS/void structure follows a power law κ ∝ T^1.75±0.02.
• The material demonstrates superior thermal isolation compared to conventional bulk insulators within the tested temperature range.
• A low power input (<400 nW) was sufficient to induce a significant temperature rise (>1 K) over a 5 cm² area without disturbing the base refrigerator temperature.

Conclusions:

• Acrylonitrile Butadiene Styrene (ABS) LEGO® blocks provide excellent thermal isolation and mechanical support at low temperatures.
• LEGO® blocks present a cost-effective and high-performance alternative to materials like Macor and Vespel for thermal management in scientific apparatus.
• The study suggests that 3D printing modular materials could enable the development of even more efficient and affordable thermal insulation solutions.