Pressure transducer

A transducer comprising

• a first Si-based chip with a first upper surface and a first lower surface opposite the first upper surface and enclosing a first chamber extending from a first opening of the first chamber at the first upper surface and through the first Si-based chip to a second opening at the first lower surface, said first Si-based chip further comprising a first diaphragm that is positioned at the first lower surface and covering the second opening,
• a second Si-based chip with a second upper surface and a second lower surface, the second Si-based chip enclosing a second chamber extending into the second Si-based chip from a third opening at the second upper surface, the first Si-based chip being positioned on the second Si-based chip with the second opening aligned with the third opening,
• said transducer, further comprising
• a third chamber being enclosed in the first substrate and extending from a fifth opening of the third chamber at the first upper surface and through the first substrate to a sixth opening at the first lower surface,
• a second diaphragm that is positioned at the first lower surface and covering the sixth opening of the third chamber, and
• a fourth chamber extending into the second substrate from a seventh opening at the second upper surface, the sixth opening of the fourth chamber being aligned with the seventh opening.