DIY check-ups on the cards

People with a chronic illness who now need regular hospital check-ups could soon be doing the blood tests at home with a battery-powered kit the size of a credit card. Patients use a tiny spring-loaded pin to prick their finger, and squeeze a spot of blood onto enzyme-coated electrodes in the card. The enzymes cause glucose or cholesterol in the blood to react and release ions, reducing the electrical resistance of the blood. Any telltale increase in current flowing between the electrodes is then recorded by a chip in the card. After running the test, the patient posts the chip…