The book "Design and Optimization of a MEMS-Based Piezoresistive Accelerometer" offers a comprehensive analysis and enhancement of the design of a tri-axial piezoresistive accelerometer, specifically developed for monitoring head injuries in sports such as motorsport and American football. The focus is on achieving the highest sensitivity through an innovative approach that captures all three axes with a single mass held by surrounding supports. The work addresses the challenges of accuracy, which is crucial in these applications, aiming for an error rate of less than 1%. By applying the Finite Element Method, the theoretical hypothesis that increasing the moment of inertia of the sensor mass enhances the device's sensitivity while simultaneously reducing crosstalk is numerically validated. The book concludes with the selection of an optimal shape that represents the outcome of the optimization process.