The spider sensor

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Spiders can sense even the slightest vibrations. Using them as an example, researchers have developed unbelievably sensitive sensors that can measure your heartbeat when applied to the skin and that understand words when taped to the larynx.

Time and again, nature’s test laboratory provides patents that are millions of years old and free of charge that scientists—especially in the sector for sensor technology—are putting to use. We recently reported on a photodetector that “sees” like a squid.

Now researchers at the Seoul National University in South Korea have been inspired by this “spidey sense” to develop a new type of highly sensitive strain sensor. The hairy arthropods have rows of tiny cracks on their legs that can sense even the slightest vibrations on the ground or in their webs.

Technical implementation involved applying a 20-nanometer-thin layer of platinum to an elastic plastic (polyurethane acrylic). Then extremely fine, controlled cracks were formed in the conductive platinum that get larger when there is a vibration, which in turn changes its electrical resistance.

These new type of sensors are a few millimeters long and have several hundred cracks that extend into the plastic. The cracks have a zig-zag pattern, which is crucial to the sensor’s sensibility because the number of the conductive bridges constantly decreases the further the crack opens. As a result, the electrical resistance does not jump when the plastic is stretched.

Like a spider, the design can detect the tiniest vibrations. The sensors are also flexible and extremely resistant, so a technical application, say in the field of wearable computing (we reported on that from electronica 2014), is fairly probable in the near future. For instance, the device could be used as a microphone. Taped to a test person’s throat, it can clearly distinguish spoken words and essentially do so regardless of ambient noise. And as a mini pulse monitor on the wrist, it could be used to measure one’s pulse and monitor pressure characteristics of the individual beats.

Spiderman

Bionics: Spiders are a model for a new type of highly sensitive vibration sensor.