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; FIG. 8 is a front perspective view of a biofeedback device showing the claimed design; and, FIG. 9 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.