Supporting information underlying the publication "Steering strategies for wasp inspired self propelled needles":
S1 Methods
The experimental procedure for each measurement inside the gelatin phantoms was executed in the sequence of steps documented in this supplementary information.
S2 Efficiency computation
In the scientific literature, wasp-inspired needle designs that can be advanced through the tissue without applying an external push force have been proposed. In this supplementary information, we discuss the needle propulsion efficiency computation for different actuation modes: (1) step-by-step motion and (2) continuous motion.
Data
In the performance evaluation, we assessed the performance of the Prebent Ovipositor Needle in soft tissue phantoms made of 5-wt% gelatin. The performance of the Prebent Ovipositor Needle was evaluated based on the propulsion and steering capabilities. We conducted three consecutive experiments to evaluate the performance of the Prebent Ovipositor Needle. First, we assessed whether the pre-bent central needle design improved the needle’s ability to steer while maintaining a self-propelled motion compared to a straight central needle design. Therefore, we evaluated the propulsion and steering capabilities of the Prebent Ovipositor Needle equipped with a pre-bent central segment, which steered downward (1R5 down), and compared it to the Prebent Ovipositor Needle with a straight central segment (1R5 forward). Second, we evaluated whether the steering performance was consistent across different steering directions by comparing the propulsion and steering capabilities when directing the pre-bent central segment upward (1R5 up) compared to downward (1R5 down). Finally, we investigated the impact of different interlocking ring designs by comparing a needle configuration with a single interlocking ring measuring 5 mm (1R5 up) to a configuration with two interlocking rings of 3 mm each (2R3 up).
Furthermore, we conducted a set of additional experiments to explore the Prebent Ovipositor Needle’s behavior in different settings. First, we performed a qualitative test to evaluate the needle’s capability to change its steering direction during insertion. Second, we investigated the behavior of the 1R5 down and 1R5 up configurations in terms of propulsion and steering capabilities using a shorter stroke length of 1 mm instead of 2 mm. For each configuration, we conducted two tests over 50 actuation cycles. Lastly, we investigated the behavior of the 1R5 forward configuration needle in stiff substrates.
Video 1: 1R5 up condition
Video with a single 5-mm ring in the upward steering configuration.
Video 2: 1R5 change steering direction
Video with a single 5-mm ring when the needle changes steering direction.
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