The use of energy harvesting for powering wireless
sensors is made more challenging
in most applications by the requirement for customi
zation to each specific application
environment because of specificities of the availab
le energy form, such as precise
location, direction and motion frequency, as well a
s the temporal variation and
unpredictability of the energy source. Wireless pow
er transfer from dedicated sources
can overcome these difficulties, and in this work,
the use of targeted ultrasonic power
transfer as a possible method for remote powering o
f sensor nodes is investigated. A
powering system for pipeline monitoring sensors is
described and studied
experimentally, with a pair of identical, non6inert
ial piezoelectric transducers used at
the transmitter and receiver. Power transmission of
18 mW (Root6Mean6Square)
through 1 m of a 118 mm diameter cast iron pipe, wi
th 8 mm wall thickness is
demonstrated. By analysis of the delay between tran
smission and reception, including
reflections from the pipeline edges, a transmission
speed of 1000 m/s is observed,
corresponding to the phase velocity of the L(0,1) a
xial and F(1,1) radial modes of the
pipe structure. A reduction of power delivery with
water6filling is observed, yet over 4
mW of delivered power through a fully6filled pipe i
s demonstrated. The transmitted
power and voltage levels exceed the requirements fo
r efficient power management,
including rectification at cold6starting conditions
, and for the operation of low6power
sensor nodes. The proposed powering technique may a
llow the implementation of
energy autonomous wireless sensor systems for monit
oring industrial and network
pipeline infrastructure.