According to a new study, the theory electrical engineers have been using to design transistors is inadequate. Engineers have to think about noise when designing these tiny electrical switches; defects in the materials used to make them can disrupt the flow of electrons, causing them to appear to fluctuate between on and off states. The current theory predicts that as transistors get smaller, these fluctuations increase in frequency. Now researchers at the National Institute of Standards and Technology (NIST) say this simply isn’t true.

The so-called elastic-tunneling model has worked well for a long time. However, the NIST researchers found that tinier transistors aren’t necessarily more error prone. That sounds like a good thing, but the researchers say it indicates a poor understanding of how transistors work in the first place. This lack of understanding could be problematic as engineers continue to miniaturize transistors in order to make cheaper, more powerful mobile devices.

The researchers found that while the fluctuation frequency doesn’t increase with miniaturization, it does increase as devices run out of power. This means that chips designed to run longer on less power will become more unreliable over time–a real problem for those hoping to install these chips in implantable medical devices like pacemakers.

These findings were presented at the IEEE International Conference on Integrated Circuit Design and Technology this week in Austin, TX.