Transabdominal Ultrasound: This is the most common type, where the transducer is moved across the mother's abdomen. Transvaginal Ultrasound: Used in early pregnancy or when a more detailed image ...

Quadcopter type drones can be flown indoors ... Not so, if you use a pair of specialised ultrasonic transducer arrays to move the air instead! (Video, embedded below) Three banks of thrusters ...