A computer can be small enough to look like a speck. The more surprising question is what must fit inside that speck: a processor, memory, a way to receive instructions, and a source of power. Shrinking those parts together leads into a world where the surrounding laboratory equipment can be much larger than the machine doing the work.

A computer measured in fractions of a millimetre

In June 2018, University of Michigan researchers described a computing device measuring just 0.3 millimetres to a side. Its processor and RAM worked with photovoltaic power and optical communication. A nearby base station supplied light for power and programming, and received the device’s data. [1]

The system was designed for precise temperature measurements in very small regions. Its tiny dimensions came with an important qualification: it lost its previous programming and data when power disappeared. The researchers themselves questioned where to draw the boundary around the word “computer.” That makes the device interesting as an engineering example, while complicating any simple size record. [1]

By 2025, tiny computers could travel

On 15 December 2025, Penn and Michigan reported microscopic swimming robots with onboard computers. Each complete robot measured approximately 200 by 300 by 50 micrometres. Those numbers describe the robot, including its computing and other components, rather than a separate processor’s dimensions. [2]

The machines could sense local temperatures and alter their movement in response. Light pulses provided both power and programming, while individual addresses allowed different instructions to be sent to different robots. The interesting achievement is the combination of sensing, stored instructions and action at that scale. [2]

Power occupies precious space

Michigan’s account describes an electronics power budget of 75 nanowatts. That is 0.000000075 watts. Even so, the solar panels occupied most of the robot’s available area, leaving the processor and program memory to share the remaining space.

The team also condensed movement-control work into a specialised instruction to help programs fit the limited memory. It is a striking example of software and hardware being designed together: the shape of the machine influences the instructions its programmer can afford to use. [3]

Moving at the scale of a speck

Computing is only part of this miniature system. A related July 2025 PNAS paper describes propulsion through electric fields and the resulting movement of surrounding liquid. Its demonstrations used onboard photovoltaic circuits to control that propulsion.

That paper focused on the movement platform and identified more complex circuitry as future work. The later December report described the integration of programmable computing. Keeping those stages separate helps explain what each result actually established. [4]

How small can computers ultimately become?

These demonstrations do not establish a universal minimum size. A record needs a definition: is it measuring a processor, a sensor system, or a complete machine with power and communication? What information survives a power cut? What supporting equipment must remain nearby?

Those questions are practical ways to read a spectacular headline. A submillimetre device may perform a carefully chosen task while depending on external illumination or laboratory instruments. The total system includes those dependencies, even when the tiny computing element sits inside a microscopic robot. [1] [3]

The achievement is already remarkable: useful sensing and programmed responses can fit into a machine almost too small to see. Future usefulness will depend on reliable power, communication and operation in the environment where that machine is meant to work.

Sources and further reading

  1. Michigan Engineering: An even smaller world’s smallest “computer” (original report, 21 June 2018)
  2. Penn Engineering: Penn and Michigan Create World’s Smallest Programmable, Autonomous Robots (15 December 2025)
  3. Michigan Engineering: World’s smallest programmable robots perform tasks (15 December 2025; updated 4 February 2026)
  4. Hanson and colleagues: Electrokinetic propulsion for electronically integrated microscopic robots, PNAS (15 July 2025)

Editorial note

Original explanatory writing prepared with AI assistance and reviewed against the primary sources linked above on 18 October 2026. Historical research dates are identified in the text. No source photographs, diagrams or program listings have been reproduced. This feature is not a hands-on test or an independent benchmark.

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