The 4th SENSIBLE workshop took place in Madrid, 16-18 October, 2019. The first half of Day 1 focused on joint research outputs pertaining to photonics and sensing within SENSIBLE Project. The second half was focused on external invitees, from industry and academia, sharing their research contributions to photonics and sensing. The second day focused on the role of science in society and how science can contribute to society. It also addressed barriers of society to science, including gender and diversity imbalance. The workshop was excellently attended by academic and industrial researchers working on photonics and sensing.