Digital response associated with HIA: semiquantitative HIA, demonstrating a clear digital distinction between the presence of the target sequence at a low concentration, with nonspecific sequences at high concentration, and with no DNA present. (A, left) 104 copies of the 26-base PL target. (B, middle) 1010 copies of the 26-base noncomplementary sequence yielding a % Dark Area similar to (C, right) no DNA present. A total of 4 μL of beads and a low aperture setting were required to generate digital response (hence, the darkness of the image). Each error bar represents the standard deviation associated with n = 4.