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Thermal Transistor: The World's Tiniest Refrigerator

Thermal transistors refrigerate one electron at a time and physicists plan to compute with heat

3 min read

1 January 2008—Traditionally, heat and electronics don’t agree. But physicists in Europe and Asia are beginning to see some signs of cooperation. A Finnish-Italian team has demonstrated that electrons in a specially designed transistor can carry away heat, making the device they built the smallest known refrigerator. Another team, from Singapore, has shown that heat can carry information in a transistor-like device, just like electrons do in conventional computers.

Researchers from the Helsinki University of Technology, in Finland, and the Scuola Normale Superiore in Pisa, Italy, have created a tiny transistor—resembling in structure if not in composition the field-effect transistors in ICs—that they call a single-electron refrigerator. Two superconducting electrodes are connected to a small micrometer-sized copper slab, about 2 mm long and 1/5 mm wide. These electrodes are analogous to the source and drain of a conventional transistor, except that they are electrically isolated from the copper by a thin layer of aluminum oxide. (Two extra electrodes are attached on both sides of the source and drain for measurement purposes.) Along the copper island is placed the ”gate,” an electrode that controls the flow of electrons through the copper slab.

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A photo showing machinery in a lab

Foundries such as the Edinburgh Genome Foundry assemble fragments of synthetic DNA and send them to labs for testing in cells.

Edinburgh Genome Foundry, University of Edinburgh

In the next decade, medical science may finally advance cures for some of the most complex diseases that plague humanity. Many diseases are caused by mutations in the human genome, which can either be inherited from our parents (such as in cystic fibrosis), or acquired during life, such as most types of cancer. For some of these conditions, medical researchers have identified the exact mutations that lead to disease; but in many more, they're still seeking answers. And without understanding the cause of a problem, it's pretty tough to find a cure.

We believe that a key enabling technology in this quest is a computer-aided design (CAD) program for genome editing, which our organization is launching this week at the Genome Project-write (GP-write) conference.

With this CAD program, medical researchers will be able to quickly design hundreds of different genomes with any combination of mutations and send the genetic code to a company that manufactures strings of DNA. Those fragments of synthesized DNA can then be sent to a foundry for assembly, and finally to a lab where the designed genomes can be tested in cells. Based on how the cells grow, researchers can use the CAD program to iterate with a new batch of redesigned genomes, sharing data for collaborative efforts. Enabling fast redesign of thousands of variants can only be achieved through automation; at that scale, researchers just might identify the combinations of mutations that are causing genetic diseases. This is the first critical R&D step toward finding cures.

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