Many arachnids use internal hemolymph pressure to actuate extension in their leg joints. The inherent large foot displacement‐to‐body length ratio that arachnids can achieve through hydraulics relative to muscle‐based actuators is both energy and volumetrically efficient. Until recent advances in nano/microscale 3D printing with two‐photon polymerization (2PP), the physical realization of synthetic complex ‘soft’ joints would have been impossible to replicate and fill with a hydraulic fluid into a sealed sub‐millimeter system. Inspired by nature, the smallest scale 3D‐printed hydraulic actuator (4.9 × 10−4 mm3) by more than an order of magnitude is demonstrated. The use of stiff 2PP polymers with micron‐scale dimensions enable compliant membranes similar to exoskeletons seen in nature without the requirement for low‐modulus materials. The bio‐inspired system is designed to mimic similar hydraulic pressure‐activated mechanisms in arachnid joints utilized for large displacement motions relative to body length. Using variations on this actuator design, the ability to transmit forces with relatively large magnitudes (milliNewtons) in 3D space is demonstrated, as well as the ability to direct motion that is useful towards microrobotics and medical applications. Microscale hydraulic actuation provides a promising approach toward the transmission of large forces and 3D motions at small scales, previously unattainable in wafer‐level 2D microelecromechanical systems (MEMS).

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Herein the electrical and microstructural characterization of additively manufactured glassy carbon fabricated via two‐photon polymerization (2PP) is reported. Thermal decomposition at elevated temperatures volatizes much of the 2PP fabricated part, converting the crosslinked photopolymer into a carbon‐rich structure. Upon heating to continued elevated temperatures the carbon material becomes increasingly conductive. The ability to control the conductivity of the pyrolyzed material is done by varying the pyrolysis temperature, with maximum conductivity obtained of roughly 2 × 104 S m−1. Microstructural characterization with Raman spectroscopy and transmission electron microscopy (TEM) confirms that the increase in conductivity comes from the increased sp2 bonding percentage in carbon and increased crystallinity. This knowledge allows for the manufacturing of predictable, well‐controlled glassy carbon resistors that are within 10% of theoretical values.