Nuclear Science User Facilities 86 Figure 3. Resistance vs. temperature for aerosol jet printed silver (top) and platinum (bottom) 3ω sensors. scientific knowledge of the in-pile performance for sensors fabricated using additive manufacturing. Further- more, the insight gained will signifi- cantly accelerate the deployment of additive manufacturing to fabricate a broad range of sensors and instrumen- tation for both in-pile and out-of-pile measurements.The research outcome will have a broad impact on a number of DOE-NE initiatives including Fuel Cycle Research and Development, the Transient ReactorTest Facility, and Advanced Modeling and Simulation. This transformative sensor manufac- turing process will advance sensor research and development activities in various areas of importance to DOE including research associated with the AdvancedTest Reactor (ATR) programs, theTransient ReactorTest Facility (TREAT) restart, Light Water Reactor (LWR) programs, and spent nuclear fuel storage. Accomplishments Silver and platinum are two sensor materials studied for this project. While silver ink is commercially available, there exists no commercial platinum (Pt) ink that can meet this project requirement.We synthe- sized the Pt nanoparticles using a wet-chemical bottom up approach. Pt nanocrystal was prepared by dissolving platinum precursor in an oleylamine, Oleic acid and 1-octa- decene mixture. Pt inks were then prepared by dissolving 0.3 mmol of the-above-fabricated Pt nanoparticles in 2 mmol chlorobenzene.Thanks to the narrow size distribution of Pt nanocrystals, the Pt ink can be well printed using ultrasonic atomization in the aerosol jet printer. Figure 1 showsTransmission Electron Micros- copy (TEM), and a Selected Area Diffraction Pattern (SAED) of the platinum nanoparticles, confirming