His research involves signal processing algorithm design with a focus on biomedical sensor arrays, such as electroencephalography (EEG), neural implants, ultrasound probes, and distributed body- and neuro-sensor networks. Applications include brain-computer interfaces, EEG-based attention decoding, cognitive control of hearing prostheses, and wearable neuro-monitoring. He also conducts research in generic signal processing techniques, with a focus on multi-channel and distributed signal processing, spatial filtering, and signal enhancement.

Dr. Bertrand is recipient of an ERC starting grant (2018) and an ERC Proof-of-concept grant (2023). He received the 2023 'Early Career Award' of the European Signal Processing Association (EURASIP), the 2012 FWO/IBM-Belgium Award, the 2013 KU Leuven Research Council Award, and several best-paper awards. He is currently Senior Area Editor for IEEE Transactions on Signal Processing, and a board member of the Benelux chapter of the IEEE Signal Processing Society. In the past, he has served as Associate Editor for the IEEE Transactions on Signal Processing (2 terms), as an Associate Editor for the IEEE EMBC (2016-2023), as lead guest editor for Signal Processing (Elsevier), as a member of the Organizing Committee of IEEE ICASSP 2023, EUSIPCO 2025 and IEEE CAMSAP 2025, and as a Technical Program Committee Member and area chair for several international signal processing conferences (IEEE ICASSP, EUSIPCO, IEEE EMBC, IEEE SAM, IEEE WASPAA, IEEE CAMSAP, and others).