Scientists at TU Wien (Vienna University of Technology) have created the world’s smallest capacitor—and while it may sound like a niche engineering feat, it could reshape the future of ultra-precise measurement tools, including atomic force microscopes.
Their work, published in Advanced Materials Technologies, shows how tiny mechanical structures can reach sensitivities limited only by the laws of quantum physics.
At the heart of the breakthrough is an astonishingly small gap: just 32 nanometers. That’s around 3,000 times thinner than a human hair.
This minuscule space separates a movable aluminum membrane from a fixed electrode, together forming a parallel-plate capacitor smaller than any ever made before.
The device is designed to detect extremely small motions, making it ideal for high-resolution sensors.
But this achievement is not just about shrinking components. It is part of a larger effort by TU Wien researchers to make quantum sensing more practical, robust, and easier to integrate into real-world devices.
Traditional systems that measure tiny motions often rely on lasers and optical setups. While these can be very precise, they are bulky, fragile, and difficult to turn into compact or portable instruments.
The TU Wien team is taking a different approach. Instead of using light, they measure vibrations using electrical or mechanical oscillations that can be built directly onto a chip.
In the new capacitor design, the aluminum membrane vibrates slightly, much like the skin of a drum. These vibrations change the electrical properties of a resonant circuit connected to the capacitor. Even the tiniest motion causes a detectable shift in the circuit’s resonance.
This method allows researchers to measure incredibly small vibrations with very little noise. Noise—random disturbances from heat or the discrete nature of electrical signals—usually limits measurement precision.
Remarkably, the TU Wien system operates at the fundamental limit set by quantum physics, without the need for optical components.
This makes it especially promising for atomic force microscopy, a technique used to image surfaces atom by atom.
In these microscopes, a sharp tip hovers just above a surface, and tiny atomic forces cause it to vibrate. By measuring those vibrations precisely, scientists can build extremely detailed images. Replacing optical readouts with compact electrical or mechanical ones could make these microscopes smaller, more robust, and easier to use.
The team has also shown that purely mechanical systems can achieve similar results. From a quantum perspective, electrical and mechanical vibrations follow the same mathematical rules. An added advantage is that mechanical systems can work at room temperature, avoiding the need for expensive cooling close to absolute zero.
The researchers believe their work demonstrates that nanomechanical devices are ready to become the foundation of a new generation of quantum sensors. With this tiny capacitor, they have opened the door to powerful measurement technologies that could soon move from specialized labs into everyday scientific tools.
