  A novel microfabricated, all-electrical measurement platform is presented for
a direct, accurate and rapid determination of the thermal conductivity and
diffusivity of liquid and solid materials. The measurement approach is based on
the bidirectional 3-omega method. The platform is composed of glass substrates
on which sensor structures and a very thin dielectric nanolaminate passivation
layer are fabricated. Using through-glass vias for contacting the sensors from
the chip back side leaves the top side of the platform free for deposition,
manipulation and optical inspection of the sample during 3-omega measurements.
The thin passivation layer, which is deposited by atomic layer deposition on
the platform surface, provides superior chemical resistance and allows for the
measurement of electrically conductive samples, while maintaining the
conditions for a simple thermal analysis. We demonstrate the measurement of
thermal conductivities of borosilicate glass, pure water, glycerol, 2-propanol,
PDMS, cured epoxy, and heat-sink compounds. The results compare well with both
literature values and values obtained with the steady-state divided bar method.
Small sample volumes (~0.02 mm$^2$) suffice for accurate measurements using the
platform, allowing rapid temperature-dependent measurements of thermal
properties, which can be useful for the development, optimization and quality
testing of many materials, such as liquids, gels, pastes and solids.
