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Success Story: Sierra Turbines


NextFlex, America’s Flexible Hybrid Electronic (FHE) Manufacturing Institute, has a state-of-the-art Technology Hub capable of fabricating fully integrated FHE devices and systems, utilizing advanced manufacturing processes and tools. The Technology Hub supports DoD as well as commercial electronics manufacturers by leveraging the benefits of FHE to reduce product costs, reduce product development cycle times, develop environmentally friendly manufacturing capabilities, and evaluate FHE equipment, substrates, materials, and components.

Sierra Turbines is a small California Defense contractor designing innovative, compact, high-efficiency turbines with features present in large scale commercial and military jet aircraft. Using additive manufacturing, they have developed a turbine engine which excels in reliability due to several design innovations such as a proprietary electronic control system, Engine Health Monitoring, and precision thermodynamic flows in both compression and combustion. Sierra Turbines’ initial market focus is on Unmanned Aerial Vehicles (UAVs) and ground based, hybrid electrical systems. Flexible Hybrid Electronics technology shows great promise and benefit to microturbine applications given the inherent nature of FHE structures with applications to structural health as well as asset and system performance monitoring.

NextFlex’s Role

A SansEC sensor consisting of silver spiral traces was conformally printed onto a 3D-printed Sierra Turbines part at NextFlex using an nScrypt printer.

Sierra Turbines proposed to leverage a SansEC sensing system from NASA Langley Research Center. SansEC is an open-circuit, resonant sensor that needs no electrical connections (thus the name SansEC or “without electrical connection”). The sensor structure consists of an array of conductive Archimedean spiral-like shapes printed onto a flexible substrate. NextFlex fabricated these samples by direct-write printing silver conductive traces onto a flexible substrate. Given device requirements from Sierra Turbines and Technology Hub capability, NextFlex developed the patterns, processes, and materials as well as fabricated prototype proof-of-concept samples of the SansEC sensors. Sierra Turbines, in turn, evaluated for purpose and application. NextFlex further fabricated another pattern, tuned to a specific Sierra Turbine application.  Given the connection with NASA, NextFlex and Sierra Turbines made special consideration to NASA-compatible toolsets and materials in their down-selection.


The successful demonstration of the FHE-fabricated SansEC device demonstrates the capability of adding electronic structures to manufactured parts using an advanced additive manufacturing process. The particular electronic structure, SansEC, can simultaneously measure different physical phenomena — temperature, fluid level, rotation rate, or wear, for example — and functions even when badly damaged. Previous variants of the SansEC sensors had been fabricated using traditional subtractive manufacturing methodologies and, as a consequence, do not have the reduced SWaP (size, weight, and power) attributes inherent for an FHE device. By demonstrating that FHE tools and processes can be applied to this particular electronic structure, Sierra Turbines is now positioned within the FHE ecosystem and supply chain. Asset monitoring and management and FHE technology will enable Sierra Turbines to competitively bid on SBIR’s modernization priorities related to Machine Learning, Autonomy, Controls, Microelectronics, and other applications related to defense and aerospace.

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