The experiments described in this paper look to further transient electronic device development by exploring the fracturing capabilities of aluminum copper (II) oxide and aluminum bismuth (III) oxide nanothermites. In particular, a quick, inexpensive test was developed that was able to characterize the substrate fracturing capability of these selectively deposited energetic materials. Using this test, aluminum bismuth (III) oxide nanothermite with near stoichiometric composition was shown to be an effective mate-rial for fracturing silicon wafers of two different thicknesses for the configuration considered. Nanothermites were deposited at various equivalence ratios, resulting in a range of damage, which enables material preparation in a given practical application to be based on the desired level of resultant fracturing. This data was subsequently compared with thrust measurements and gas shock formation in an effort to correlate thrust production to the severity of fracturing produced.

Currently, there is very little systematic work quantifying the thrust or heat applied to an electronic circuit or other substrate by a deposited layer of energetic material. A better understanding of the interactions between nanoscale energetic materials and electronic systems, as a function of stoichiometry, is needed. For this purpose, formulations of nAl-CuO and nAl-Bi 2 O 3 nanothermites were prepared at different equivalence ratios and selectively deposited onto electronic circuit analogues (silicon wafers) and the amounts of thrust production and heat deposition were measured. Both nanothermite systems produced maximum thrust near stoichiometric ratios, accom-panied by a shock wave, with minimal thermal effects due to large gas production, which ejects the hot products of the substrates. Conversely, more fuel-rich mixtures led to significantly decreased thrust while increasing heat deposition due to the lower gas production, which allowed more heat to diffuse to the substrates. This shows that the energetic material response can be tuned between thrust or heat deposition by just varying the equivalence ratio. The conductive heat transfer within the silicon substrates from the nAl-CuO system increased more than the nAl-Bi 2 O 3 system at fuel rich conditions due to its higher heat of combustion.

Energetic porous silicon is investigated as an actuator for micro-propulsion based on thrust and impulse measurements for a variety of porous silicon porosity conditions. Porosity of 2 mm diameter, porous silicon microthruster devices was varied by changing the concentration of hydrofluoric acid and ethanol in an etch solution, by changing porous silicon etch depth, and by changing the resistivity of silicon wafers used for the etch process. The porosity varied from 30% to 75% for these experiments. The highest mean thrust and impulse values measured with a calibrated Kistler 9215 force sensor were 674 mN and 271 μN s, respectively, with a 73% porosity, 2 mm diameter porous silicon device etched in a 3 : 1 etch solution on a 3.6 Ω cm wafer to a target etch depth of 30 μm. As a result of changing porosity, a 23×  increase in thrust performance and a 36×  increase in impulse performance was demonstrated. Impulse values were also validated using a pendulum experiment in which the porous silicon microthruster was unconstrained, but several non-linearities in the pendulum experimental setup resulted in less consistent data than when measured by the force sensor for microthrusters at this size scale. These thrust and impulse results complement previous work in determining the effect of porosity on other porous silicon reaction metrics such as flame speed.

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