A method of detecting activity with a MEMS accelerometer stores a value of acceleration, then measures acceleration at a later time, calculates a change in acceleration using the measured acceleration and the stored acceleration, and compares the change in acceleration to an activity threshold to detect activity. The depositiontrimming process includes an adsorption process for allowing a silicon-containing gas to be adsorbed onto the surface of the organic film and an oxidation process in which the line width of the organic film is trimmed while the adsorbed silicon-containing gas is converted into a silicon oxide film. The filler is effectively employed in a polymer composite in which the advantages of the tubular nanoparticle filler are provided with improved or equivalent mechanical performance of the composite. In this case the top solar cell has the largest bandgap, the bottom solar cell has the smallest bandgap, and intervening solar cells have intermediate bandgaps that descend in magnitude from the top to the bottom solar cell.