Humidity sensor inspired by camel noses can trace moving fingers
Scientists have developed an advanced new type of humidity sensor that takes inspiration from camel noses to overcome shortcomings with existing solutions. The novel device is capable of detecting low levels of water molecules in the air and opens up some interesting possibilities, including finding water sources in extreme environments or contactless interactions with computers.
The different humidity sensors currently on the market have their strengths and weaknesses, with some only offering a low sensitivity for water detection, and others offering high sensitivity but having their performance compromised by environmental conditions, such as exposure to harsh sunlight, for example. Scientists in China set out to develop one that ticks both durability and sensitivity boxes, and to do this they turned to the famously sensitive noses of camels.
The noses of these "ships of the desert" feature narrow passages with large surface areas lined by water absorbing mucus, which change capacitance as humidity in the air fluctuates. This makes the animals very effective at sniffing out water in arid environments, so the scientists used their noses as a blueprint for a new type of humidity sensor with a high degree of sensitivity.
The device consists of a porous polymer network coated with molecules called zwitterions, which attract moisture and mimic the ability of camel mucus to change capacitance as humidity varies. The sensor proved both durable and highly sensitive in the team's experiments, successfully detecting changing humidity in hot industrial exhaust and proving capable of quickly distinguishing between fresh, stale and dry leaves.
It was also capable of finding the location of a water source and could detect moisture coming from a human body. In these experiments, the sensor was shown to respond to changes in perspiration as a person exercised, and could detect a human finger, even tracking its movements in a V or L shape. The scientists say this could see the device serve as a touch-free interface for interacting with computers, and that the prototype also serves as a general design principle that can be applied to the development of other high-performance chemical sensors.
The research was published in the journal ACS Nano.
Source: American Chemical Society