This technology uses a metalorganic chemical vapor deposition (MOCVD)
system to grow a ZnGa2O4 (ZGO) with spinel epilayer on a sapphire subst
rate. The MOCVD growth system of ZGO sensing epilayer is capable for m
ass-produced. This ZGO epilayer can be produced into a gas sensor with a
surrounding heater by a simple process. Particularly outstanding, this spin
el metal oxide is currently the only metal oxide film that can sense nitric o
xide. The research found that the gas sensor made of spinel thin-film only
has excellent response and high selectivity for NO gas. With proper electr
ode design, when in the case of NO gas, the resistance measured by this el
ectrode will change. Combined with the reading signal of the circuit, the
measured signal can be transmitted to the cloud by 4G network. Even in a
harsh environment, the signal can be received at a safe place.
On the other hand, in order to allow the gas sensor to achieve a highly sen

sitive response, it is usually heated. In order to increase the temperature o
f the surface of the ZGO epitaxial film to achieve the operating range of th
e gas sensing element, it is also desirable to pursue the minimum work To
reduce power consumption, and minimize heat dissipation, the common
gas sensor adopts a suspended design, using air as its thermal insulation s
hield.
This technology also proposes to produce the heater on the same plane of
the sensor with the insulation packaging. The heater can instantly heat th
e sensor to 300°C, which contributes to improve the sensing ability of the
gas sensor. Compared with the traditional gas sensor with a micro-electro
mechanical suspended diaphragm, this design will have a simpler manufa
cturing process and a more robust mechanical structure. Moreover, a spec
ial circuit is designed to keep the resistance of the heater at a constant vol
tage for maitaining heater at a constant temperature. The gas sensor can
measure as low as the ppb level, and has a very high gas selectivity.