Abstract. Biomedical optical devices are widely used for clinical detection of various tissue anomalies. However, optical measurements have limited accuracy and traceability, partially owing to the lack of effective calibration methods that simulate the actual tissue conditions. To facilitate standardized calibration and performance evaluation of medical optical devices, we develop a three-dimensional fuse deposition modeling (FDM) technique for freeform fabrication of tissue-simulating phantoms. The FDM system uses transparent gel wax as the base material, titanium dioxide (TiO 2 ) powder as the scattering ingredient, and graphite powder as the absorption ingredient. The ingredients are preheated, mixed, and deposited at the designated ratios layerby-layer to simulate tissue structural and optical heterogeneities. By printing the sections of human brain model based on magnetic resonance images, we demonstrate the capability for simulating tissue structural heterogeneities. By measuring optical properties of multilayered phantoms and comparing with numerical simulation, we demonstrate the feasibility for simulating tissue optical properties. By creating a rat head phantom with embedded vasculature, we demonstrate the potential for mimicking physiologic processes of a living system. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Binder jetting additive manufacturing (BJAM) is a widely studied technique fabricating metal parts. In this study, bimodal 316L stainless steel powder mixture of coarse (D50 -34.1μm) and fine (D50 -6.28μm) powders were designed for BJAM. Infiltration was used to improve the density of BJAMed parts. Bimodal powder mixture showed clear advantage over unimodal powder system on density and mechanical property of BJAMed parts. Upon solidphase sintering, BJAMed 316 stainless steel of bimodal powder mixture (9:1 mass ratio of coarse to fine powder) showed relative density 97.19% and tensile strength 343.62 MPa, as compared with relative density 84.55% and tensile strength 291.59 MPa for pure coarse powder. For the same bimodal powder mixture, bronze infiltration, compared with solidphase sintering, resulted in noticeably higher relative density 99.92% and tensile strength 621.63 MPa. Compared with solid-phase sintering, infiltration significantly reduced the volumetric shrinkage.

Currently, the research on mechanical behavior and cutting performance of functionally graded carbides is quite limited, which limits the rapid development of high-performance cemented carbide cutting tools. Based on WC-Co-Zr and WC-Ni-Zr, this study synthesized two kinds of cemented carbide cutters, i.e., the cemented carbide cutters with homogeneous microstructure and functionally graded carbide (FGC) cutters with FCC phase ZrN-enriched surfaces. Furthermore, TiAlN coating has been investigated on these carbide cutters. Mechanical behavior, friction, wear performance, and cutting behavior have been investigated for these coated carbides and their corresponding substrates. It was found that, as compared with coated cutters on WC-Co/Ni-Zr carbide substrates with homogeneous microstructures, the coated cutters on WC-Co/Ni-Zr FGC substrates with FCC phase-enriched surfaces show higher wear resistance and cutting life, and the wear mechanism during cutting is mainly adhesion wear.