The Stark Medical Scanner is a device that scans blood samples for toxins by pricking the user's finger with a needle and drawing blood. It is a Stark Industries product.
Tony Stark first used this device when he opened the Stark Expo, when his father was on screen introducing his vision. Stark went backstage and used the scanner, by putting his finger on it. The device took a sample of blood to measure the toxins.
The next time he used it was at his house and then again was when Stark went to Monaco, when he decided that he needed to live every minute as if it were his last.