Micromachined cryogenic cooler for cooling electronic devices down to 30 K

Cryogenic temperatures are required for improving the performance of electronic devices and for operating superconducting sensors and circuits. The broad implementation of cooling these devices has long been constrained by the availability of reliable and low cost cryocoolers. After the successful development of single-stage micromachined coolers able to cool to 100 K, we now present a micromachined two-stage microcooler that cools down to 30 K from an ambient temperature of 295 K. The first stage of the microcooler operates at about 94 K with nitrogen gas and pre-cools the second stage operating with hydrogen gas. The microcooler is made from just three glass wafers and operates with modest high-pressure gases and without moving parts facilitating high yield fabrication of these microcoolers. We have successfully cooled a YBCO film through its superconducting transition state to demonstrate a load on the microcooler at cryogenic temperatures. This work could expedite the application of superconducting and electronic sensors and detectors among others in medical and space applications. (paper)