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A human arm is a vital instrument for performing various tasks. To imitate natural design, we developed and characterized a bioinspired modular soft robotic arm fabricated from fabric thermoplastic polyurethane (TPU). The soft robotic arm comprises three link sections, three joints, and an end-effector. Although some soft robotic arms have been designed, they are primarily fabricated with continuous shapes. Therefore, we fabricated a modular and customizable soft robotic arm with different requirements, allowing fast fabrication, prototyping, and assembly, and comprising joint and link sections that can be incorporated together to form an arm with an adjustable number of joints. An analytical approach was used to model the different bending angles at diverse pressures, and a data-driven approach was used to model the angular position with respect to the pressure. Forward and inverse kinematics were performed to calculate the orientation, position, and joint angle of each component. The results showed that the maximum bending angles for each corresponding joint were generally larger for joints number one and three but smaller for joint number two. Moreover, motion analysis data showed that each joint exhibited different bending patterns, and our bio-inspired arm design demonstrated that it could conduct diverse motions at various pressures, in contrast to the soft arms seen in the literature. Additionally, the modular construction of the arm allows it to access larger workplaces, and a gripper should be included in future versions to increase the arm’s capabilities.

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Paper-based platforms are ideal for on-site surveillance of infectious diseases in low-resource settings due to their simplicity, self-containment, and low cost. The two most popular materials used in paper-based platforms are nitrocellulose and cellulose. The nitrocellulose membrane has a high protein binding affinity, but its high price is an issue. Cellulose paper is inexpensive and allows intricate fluidic control for more sophisticated biochemical reactions, but it has a low protein binding affinity. By examining the microstructure of cellulose paper, we discover that cellulose fibers in the paper matrix are covered by thin films, which possibly result from the additives used in the paper-making process. Our finding suggests that the thin films are inert to protein adsorption. By selectively depleting the inert films with reactive plasma, we were able to enhance the protein adsorption to the cellulose paper and improve the performance of lateral flow assays. The performance of certain lateral flow assays on the plasma-treated cellulose paper is equivalent to or better than that on the nitrocellulose membrane. This leads us to believe that cellulose paper with a microstructure exclusively designed for protein binding, either by refined paper manufacturing process or by post-manufacture modification such as the plasma treatment presented herein, can potentially replace nitrocellulose as a less expensive paper substrate for point-of-care rapid test kits.