Biofeedback device

FIG. 1 is a front perspective view of a biofeedback device showing the claimed design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a first side view thereof;

FIG. 5 is a second side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a front perspective view of a biofeedback device showing the claimed design.

The broken lines shown in the figures depict portions of the biofeedback device that form no part of the claimed design.