New energetic materials (EMs) are the key to great advances in microscale energy-demanding systems as actuation part, igniter, propulsion unit, and power. Nanoscale EMs (nEMs) particularly offer the promise of much higher energy densities, faster rate of energy release, greater stability, and more security (sensitivity to unwanted initiation). nEMs could therefore give response to microenergetics challenges. This paper provides a comprehensive review of current research activities in nEMs for microenergetics application. While thermodynamic calculations of flame temperature and reaction enthalpies are tools to choose desirable EMs, they are not sufficient for the choice of good material for microscale application where thermal losses are very penalizing. A strategy to select nEM is therefore proposed based on an analysis of the material diffusivity and heat of reaction. Finally, after a description of the different nEMs synthesis approaches, some guidelines for future investigations are provided.

https://homepages.laas.fr/rossi/Publi/Nanoenergetics-Review-JMEMS-2.pdf

Nanoenergetic Materials for MEMS: A Review

The paper describes a new architecture of a Safe Arm and Fire device (SAF) that could constitute a real breakthrough for safe miniature fuzing device. On the one hand, it takes all the functions embodied in a conventional mechanical arm and fire system and integrates them in a single 1 cm 3 package made of assembly of different parts. On the other hand, for the first time, it combines a mechanical arming unit with electrical safety functionalities on the same silicon initiator's chip. It respects the STANAG 4187 norm (1 A/W during 5 min of not fire) and requires only 635 mW for ignition. The paper presents the design, fabrication and test of one miniature SAF device integrating a micropyrotechnical actuation.

Integration of a MEMS based safe arm and fire device

An EC funded MicroPyros project has permitted to develop the technologies to fabricate, assemble and command solid propellant microthrusters arrays for thrusts of a few of milli Newtons The prototype built for space application has 100 individually addressed ∅ 1.5 mm × 1.5 mm thrusters on 576 mm2. Nozzles’ throats are 250 μm and 500 μm. This paper reviews the prototype structure and details the final processes for the fabrication and assembling. This paper presents also a new addressing technology based on polysilicon threshold elements used for the addressing and heating of each thruster in the array. With polysilicon threshold element, ignition success is of 100% with an input power of 250 mW using a zirconium perchlorate potassium (ZPP) material. Then, the combustion of a glycidyle azide polymer (GAP) is sustained in the chamber and generate thrusts in the range of 0.3–2.3 mN depending of the micronozzle dimension.

/pdf/matrix-of-10-10-addressed-solid-propellant-microthrusters-57bg5fjajs.pdf

Matrix of 10 × 10 addressed solid propellant microthrusters: Review of the technologies

A review of the micropyrotechnics related works is done. Micropyrotechnics is the integration of an energetic material into microsystem, for which the thermal, mechanical and chemical energy released by decomposition can be exploited. After a state-of-the art of micropyrotechnics and its application to microsystems, authors try to identify obvious difficulties and insufficiencies that may require future work, particularly in terms of the development of new materials, new modelling tools and new processes for integration into microsystems. A section is dedicated to the current micropyrotechnic applications including emerging ones. In conclusion, the perspectives of this discipline are discussed and the authors try to give some guidelines for future investigations.

/pdf/micropyrotechnics-a-new-technology-for-making-energetic-4ym9h5pgws.pdf

Micropyrotechnics, a new technology for making energetic microsystems : review and prospective

Low-temperature co-fired ceramic (LTCC) technology has been first successfully employed for the realization of a solid propellant microthruster. The microthruster has potential applications in microspacecraft as an excellent micropropulsion system for high-accuracy station keeping, attitude control, drag compensation and orbit adjust. The design, fabrication and experimental investigation of LTCC microthrusters are reported. Results from experiments on microcombustion, and thrust and impulse measurements both at sea level and in vacuum are presented. Initial tests employing gunpowder-based solid propellant have produced 3.81 × 10−5–1.27 × 10−4 N s of total impulse and 5.55–14.41 s of specific impulse at sea level, and 1.31 × 10−4–2.79 × 10−4 N s of total impulse and 19.05–31.55 s of specific impulse in vacuum. The performance of the LTCC solid propellant microthruster is also compared with that of a silicon-based solid propellant microthruster.

https://iopscience.iop.org/article/10.1088/0960-1317/15/5/007/pdf

Development of a low-temperature co-fired ceramic solid propellant microthruster

The prototype of a solid propellant rocket array thruster for simple attitude control of a 10 kg class micro-spacecraft was completed and tested. The prototype has 10×10 φ0.8 mm solid propellant micro-rockets arrayed at a pitch of 1.2 mm on a 20×22 mm substrate. To realize such a dense array of micro-rockets, each ignition heater is powered from the backside of the thruster through an electrical feedthrough which passes along a propellant cylinder wall. Boron/potassium nitrate propellant (NAB) is used with/without lead rhodanide/potassium chlorate/nitrocellulose ignition aid (RK). Impulse thrust was measured by a pendulum method in air. Ignition required electric power of at least 3–4 W with RK and 4–6 W without RK. Measured impulse thrusts were from 2×10−5 Ns to 3×10−4 Ns after the calculation of compensation for air dumping.

Ryuichiro Hosokawa

Papers

MEMS-Based Solid Propellant Rocket Array Thruster

Development Study on A Micro-Solid Propellant Rocket Array Thruster