The development of increasingly sensitive force probes is essential both from an application perspective (smartphones’ accelerometers, gravimeters for monitoring Earth's climate [1], etc.) and from a fundamental perspective (measuring forces beyond the Standard Model [2]). To address these questions, it is necessary to have a force sensors that is simple, robust, and highly sensitive. A promising approach is the levitation of particles in a vacuum, which allows for very high sensitivities due to the weak coupling between the particle and its environment. Levitation relies on an optical trap, which uses the forces associated with a laser beam to trap a nanoparticle at the focal point of a objective (see figure). The particle then behaves like a mechanical oscillator with a very high-quality factor, making it highly sensitive to applying an external force. In this context, this project aims to develop a force sensor based on optical levitation and demonstrate its sensitivity, particularly in the measurement of gravity. Depending on their interests, the student involved in the project may choose to focus either on developing a prototype of an integrated and portable accelerometer or on pushing the force measurement sensitivity to fundamental classical and quantum limits, in order to measure gravitational forces beyond currently accessible sensitivities.