Figure 9.

Effect of environmental magnetic noise on HAND counts. Data is from one subject with a stroke (BBT score = 40) who used the Manumeter for 21 days. The subject wore the Manumeter without the magnetic ring ([−] ring) for 6 of the 21 days and with the ring ([+] ring) for the remainder of the days. The HAND counts and UE activity counts (derived from the wrist accelerometer in the Manumeter wristband) were smoothed using a 1-h running window average and are presented in the middle plot as the average across the days with and without the ring. The left and right plots show the distribution of hand and activity counts per hour with a line representing the average intensity. Note that HAND counts dropped to ~200 counts/hour when the ring was not worn, compared to ~1000 counts/hour when the ring was worn (left distributions, mean bars). Activity counts measured with wrist acceleration stayed about the same on average (right distributions, mean bars), whether the ring was worn or not, as expected. The ~200 HAND counts/hour measured without the ring are due to environmental magnetic noise.