Self-powered 'paper chips' could help sound an early alarm for forest
fires

Date:
June 17, 2020
Source:
American Chemical Society
Summary:
Recent devastating fires in the Amazon rain forest and the
Australian bush highlight the need to detect forest fires at early
stages, before they blaze out of control. Current methods include
infrared imaging satellites, remote sensing, watchtowers and aerial
patrols, but by the time they sound the alarm, it could be too
late. Now researchers have developed self-powered ''paper chips''
that sense early fires and relay a signal.



FULL STORY ========================================================================== Recent devastating fires in the Amazon rain forest and the Australian bush highlight the need to detect forest fires at early stages, before they
blaze out of control. Current methods include infrared imaging satellites, remote sensing, watchtowers and aerial patrols, but by the time they
sound the alarm, it could be too late. Now, researchers reporting in ACS Applied Materials & Interfaces have developed self-powered "paper chips"
that sense early fires and relay a signal.


========================================================================== Previously, scientists have proposed placing a network of sensors in
the forest that could detect changes in temperature, smoke or humidity
and wirelessly transmit a signal to responders. However, such a system
hasn't yet seemed practical because all of the sensing components
require power. Batteries would eventually go dead and need to be
replaced. Thermoelectric materials, which convert temperature differences
into electricity, could simultaneously detect temperature increases
from fires and power themselves. However, most of these materials are
solid inorganic semiconductors, which are often expensive, rigid and environmentally unfriendly. Yapei Wang and colleagues wanted to find
out if ionic liquids could be used as thermoelectric materials for fire sensing. These fluids are salts in the liquid state, and two different
types of ionic liquids can be connected in series to generate signals.

To make paper-based thermoelectric sensors, the researchers chose two
ionic liquids that behaved differently when the temperature increased:
One adsorbed to the surface of gold electrodes, while the other desorbed, producing opposite (positive or negative) voltages. They deposited each
ionic liquid like an ink between two gold electrodes that were sputtered
onto a piece of ordinary paper.

When connected in series, the two ionic liquids produced an electric
signal when a large temperature difference occurred, as would happen in
a fire. In a pilot test of the new sensor, the researchers attached one
to a houseplant.

When they placed a flaming cotton ball close to the plant's roots, the temperature at the bottom of the sensor quickly increased, producing a
voltage signal that an attached microcomputer chip wirelessly transmitted
to a receiver. Upon picking up the signal, the receiver activated a
sound alarm and a red light. The thermoelectric paper chips are cheap
($0.04), and the materials are eco-friendly, the researchers say.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Xun Wu, Naiwei Gao, Xiaoting Zheng, Xinglei Tao, Yonglin He,
Zhiping Liu,
Yapei Wang. Self-Powered and Green Ionic-Type Thermoelectric Paper
Chips for Early Fire Alarming. ACS Applied Materials & Interfaces,
2020; 12 (24): 27691 DOI: 10.1021/acsami.0c04798 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200617121443.htm

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