  Various fields, including medical and human interaction robots, gain
advantages from the development of bioinspired soft actuators. Many recently
developed grippers are pneumatics that require external pressure supply
systems, thereby limiting the autonomy of these robots. This necessitates the
development of scalable and efficient on-board pressure generation systems.
While conventional air compression systems are hard to miniaturize,
thermopneumatic systems that joule-heat a transducer material to generate
pressure present a promising alternative. However, the transducer materials of
previously reported thermopneumatic systems demonstrate high heat capacities
and limited surface area resulting in long response times and low operation
frequencies. This study presents a thermopneumatic pressure generator using
aerographene, a highly porous (>99.99 %) network of interconnected graphene
microtubes, as lightweight and low heat capacity transducer material. An
aerographene pressurizer module (AGPM) can pressurize a reservoir of 4.2 cm3 to
about ~140 mbar in 50 ms. Periodic operation of the AGPM for 10 s at 0.66 Hz
can further increase the pressure in the reservoir to ~360 mbar. It is
demonstrated that multiple AGPMs can be operated parallelly or in series for
improved performance. For example, three parallelly operated AGPMs can generate
pressure pulses of ~215 mbar. Connecting AGPMs in series increases the maximum
pressure achievable by the system. It is shown that three AGPMs working in
series can pressurize the reservoir to ~2000 mbar in about 2.5 min. The AGPM's
minimalistic design can be easily adapted to circuit boards, making the concept
a promising fit for the on-board pressure supply of soft robots.
