Some of the smallest PCBs I’ve designed, these Gas Sensor boards are just 35 mm by 22 mm (1.38 inches x 0.88 inches) in size.
The board below is a four layer board using metric 1608 (inch 0603) SMT passives.
Toxic Gas Sensor PCB
The board below is a six layer board using metric 1005 (inch 0402) SMT passives.
Dual Toxic Gas Sensor PCB
Despite the small area available for component placement the designs were completed without having to use buried or blind vias.
I had the opportunity to tour both the Diamond Light Source and the ISIS Pulsed Neutron and Muon Source at Rutherford Appleton Laboratory as a member of the IET. Both were very interesting and although Diamond Light looks the more impressive from the nearby stretch of the Ridgeway, ISIS perhaps does the more impressive science.
Xgard at Diamond Light Source
Diamond Light Source use Crowcon Xgard Gas Detectors as can be seen in the photographs above. This is one of the products I worked on for Crowcon, re-laying out the Xgard Flammable, Toxic and Oxygen amplifier and sensor PCBs.