Microscale biaxial accelerometers are required to be sensitive to applied accelerations and manufacturable by means of microelectromechanical systems technology. In order to meet these requirements, a compliant realization of biaxial accelerometers, dubbed simplicial biaxial accelerometers, has been proposed, as reported in this paper. Notched joints, to realize what is termed -joints in the parallel-robots literature, are employed and then improved by the introduction of Lamé-shaped hinges serving as flexible joints. The sensitivity of the simplicial biaxial accelerometers in estimating accelerations is investigated and validated by means of finite element analysis. The sensing system is embedded in the simplicial biaxial accelerometers, with piezoresistive sensing technology adopted in the instrumentation design. Using the principles of piezoresistive sensing, the electronic layout is developed for the accelerometer. Through the piezoresistive analysis implemented on the finite element model of the simplicial biaxial accelerometers, the matrix that maps voltage signals into acceleration signals is derived. By virtue of both the structural and electronic designs, the accelerometer is observed to be sensitive to accelerations in its plane, but fairly insensitive to accelerations in any of the other four directions of the rigid-body motion. Finally, prototypes were fabricated with microelectromechanical systems technology to test the microfabrication feasibility of the structure and measurement system of the accelerometer. Test results are the subject of a forthcoming paper.