825751.fig.001
Figure 1: The design of the double-blind (practitioner-patient blinding) skin-touch placebo needle and matching penetrating needle [3, 4]. Both needles comprise an opaque guide tube (1) and upper stuffing (2). The body of the penetrating needle (3) is longer than the guide tube by an amount equal to the insertion depth, but the needle body of the skin-touch placebo needle (4) is just long enough to allow its blunt tip to press against the skin when the needle body is advanced as far as possible. The skin-touch placebo needle contains lower stuffing (5). Both needles have a stopper (6), which prevents the needle handle (7) from advancing further when the sharp tip of the penetrating needle (8) or the blunt tip of the skin-touch placebo needle (9) reaches the specified position. The pedestal (10) on each needle is adhesive, allowing it to stick firmly to the skin surface.