Computational design of Micro-Electro-Mechanical Systems (MEMS) involves several strongly coupled physical disciplines, including fluid mechanics, heat transfer, stress/deformation dynamics, electronics, electro/magneto statics, calorics, biochemistry and others. CFDRC is developing a new generation multi-disciplinary CAD system for MEMS using highfidelity field solvers on unstructured, solution-adaptive grids for a full range of disciplines. The software system, ACE + MEMS, includes all essential CAD tools; geometry/grid generation for multi-discipline, multi-equation solvers, GUI, tightly coupled configurable 3-D field solvers for FVM, FEM and BEM and a 3-D visualization/ animation tool. The flow/heat transfer/calorics/chemistry equations are solved with unstructured adaptive FVM solver, stress/deformation are computed with a FEM STRESS solver and a FAST BEM solver is used to solve linear heat transfer, electro/magnetostatics and elastostatics equations on adaptive polygonal surface grids. Tight multidisciplinary coupling and automatic interoperability between the tools was achieved by designing a comprehensive database structure and APIs for complete model definition (geometry, mesh, boundary/volume conditions, simulation controls, solution fields, etc.). The virtual model definition is implemented in Data Transfer Facility (DTF), a publicly available tool described in this paper. The paper presents overall description of the software architecture and MEMS design flow in ACE+MEMS. It describes current status, ongoing effort and future plans for the software. The paper also discusses new concepts of mixed-level and mixed-dimensionality capability in which 1D microfluidic networks are simulated concurrently with 3D high-fidelity models of discrete components (e.g., pumps, mixers, valves, …).