SENESKY Debbie Extreme Sensors 25 Feb 2013

XLab  =  extreme enviroment  microsystems  lab
and CIS = center for integrated systems..

improve power plants
aircraft engines
auto engines and space  applications.

try to improve efficiency...

put sensors directly into harsh enviro at  600 degr C...

how do u make them and use them

2006 energy flow in USA...

petroleum  40 %
natl gas  23%
coal 23
nuclear 8
hydro  2.7
biomass 2.7
etc.

25% loss in generation and  xmission and distrib losses

50% loss  in generation  and 

calif energy madate

want 80%  reduc of co2 by 2050  etc. and closer in targets

sensors are subject to
chemical attack , nuclear radiation, heat, pressure, acceleration  300 to 600 degr C

try to monitor processes directly with integrated sensors...

try to put into a wireless multichip sensing module  right in harsh enviro...

eg  gas turbine engines... costs 1 M  dollars just to open it up!  (for inspection)

small gains in efficiency can make huge diff.

now... interval based maintenance... use fiber optics to look inside...
not in real time...

also subsurface monitoring...  well bores;  2 to 5 miles below.. deep sea...
geothermal...

eg pour cement into a well bore...

to prevent blow outs...

how to make these? (ie what temp, pres are they subject to)

silicon carbide is what she uses...for her sensors

wide band gap...

can dope it to p or n type...

c = cubic
h =hexagonal

3c=siC  etc.

why silicon carbide...

2830  degr C  sublimes.... v stable  silicon carbide...

3 electron volt band gap...

diamond does not work... turns to graphite...

can ruggediz  devices with thin coatings of SiC...only 40 nm  coating works...

(used to reinforce drill bits)

very stable...

put into well bores....

SiC die  ... can withstand supercrit  water...

can we make  sensors of it...

make whole system of SiC....

LPCVD  low press   CVD  polycrystalline  (chemovapor depos)

can make free standing beams...

resonant strain sensor...

guitar string... tension.. get change in sound...

tines of fork...  sense it with comb fingers...

hovering structure  (tines of fork)

it continues to resonant even at 600 degr C !!!  and even with dry steam!

but how abt metallization?

perhaps use platinum...

put graphene btwn plat and SiC and it works...

how abt electronics  (amplifers etc)

it works...

how abt powering them  with energy?

put an impuse harvester that generates electricty from piezoelectric effect...

put AlN = aluminum nitride on surface of  diaphragm...

sensors usu need microwatts... use heat to get energy...

she shows a telemetry module (Colpitts circuit)  util  a SiC MOSFET at 400 degr C.

in-situ  combustion monitoring...

put sensors in the combus chamber and at exhaust...

try to put diftt types of fuel in engine... biomass andpetroleum...

calif  stringent regs on cars...

v stringent on particular matter...

one grain of rice  0.02 grams...

2015  less than 1/2 grain of rice per mile  of particualtes...

also must reduce  NMOG and NOx...

want feedback to catalytic converter...

how soot being emitted by your car in RT.

******  GALLIUM NITRIDE

many industries  using it...
high power electronics, LEDs  sensors, solar cells,   RF resonators, and nanostrucs...

it is piezoelectric... piezoresistive... change in resistance and pyroelectric...
voltage gen from ehat...  can use for sensing...

can use for    many sensing modes...

put into exhaust stream and feedback to engine control...

pressure sensitive diaphragm... with GaN and AluminumGalNitride...

can do particulate, pressure, accel pressure,  energy harester  all on same chip...

chip 3mm by 3mm  putinto walls of combus chamber...

put into  geothermal,  oil and gas explor, industrial gas turbines, auto engines and aircraft engines...

tech challenges:

how to communic with them...  couple hundreds of these together... smart dust...

power sorucesa:  radioactive  sources
energy scavenging  from vibration eg
supercapacitors...

summary:
ceramic  semis  SiC and GaN  can be used in extremes

can measure gas content...
monitor struc health of critical components
provide rt feedback...

do all sensing  multimod  and energy haresting on one chip...

she ws formerly at UC Berk...