A vacuum-cavity-insulated flow sensor and related fabrication method are described. The apparatus is manufactured through applying the printed wire board in the registration and allowing the connector’s multiple pins and the antenna pin to protrude through corresponding holes in the printed wire board. The width of the second opening is adjusted such that the angled implant is substantially blocked from the second transistor area. The groups of features may be a group including features currently used by the machine learned model, a group including all available features, and one or more intermediate groups.