The robotic pill collection chambers are designed to entrap biomarkers within an absorbent polymeric matrix while enabling fluid to permeate through it. The sodium polyacrylate enclosed between the porous membranes absorbs an aqueous solution that permeates through the membrane. The hydrogen bond interactions between the carboxylic groups of the absorbent material and the surrounding water molecules results in the expansion of the polymeric matrix and the untangling of the polymeric chains, creating swelling as liquid is absorbed (Figure 3a).\cite{Liu2019} The absorbent matrix dynamically increases biomarker retention in the device, while fluid permeates through the collection chamber. The resulting expansion and swelling enable the physical entrapment of biomarkers in between the swollen hydrogel’s matrix. Instead, without the use of the hydrogel matrix, both the liquid and biomarkers would leak freely. The dry absorbent powder can expand rapidly (~10 sec) to form a large hydrogel matrix, as shown in Figure S2 and Video S1.