Analysis of Electromagnetic Interference and Shielding in the mu LED Optrode Based on Finite Element Method

Monolithic integrated mu LED optrode has promising applications in optogenetics due to their ability to achieve more optical channels in a smaller footprint. The current used to drive the mu LED will cause electromagnetic interference (EMI) noise to the recording electrodes at a very close distance. Utilizing a grounded metal shielding layer between the active device and the electrode can potentially reduce the interference. In this paper, multi-dimensional mu LED optrode models are set up according to the real device. By numerically analyzing the electromagnetic interference between the mu LED and recording electrodes, several optimized shielding schemes are evaluated by simulations and experiments. Some important process and layout parameters that may influence the shielding effect are studied through the finite element method (FEM). Different circuit models based on the corresponding test environment are built to analyze the simulation and experiment results. A new PCB with a shielding layer has been designed and initially verified. The proposed novel computational model can analyze EMI quantitatively, which could facilitate the design of low-noise mu LED optrode with reasonable shielding and packaging.