Capsule endoscopy is one of the great advances of modern medicine from a patient perspective, if only because it is an alternative to having a long tube fitted with a video camera inserted down one's throat or through one's rectum. Instead, the patient swallows a capsule fitted with a miniature video camera that transmits pictures of the stomach and intestinal walls as it moves through the digestive tract. Because the device is ingested, the capsule's material must be biocompatible while withstanding exposure to stomach acid and intestinal flora. It also must be transparent to allow the camera to film the fantastic voyage. A special grade of Makrolon polycarbonate from Covestro (formerly Bayer MaterialScience and headquartered in Leverkusen, Germany) met those requirements for Chinese medical device manufacturer Shenyang Shangxian Technology.
The plastic is highly transparent, enabling the capture of clear, high-resolution images. The material also affords considerable design freedom, notes Covestro, thus facilitating a large filming angle for the camera. These properties contribute to eliminating uncertainties in the diagnosis of gastrointestinal diseases without causing patient discomfort.
Various grades of Makrolon have been developed for a range of other medical applications including dialysis devices, tube connectors, blood filters, stopcocks and injection systems. The material's processability, low shrinkage and low water absorption enable the design of thin-wall, lightweight parts with dimensional stability, notes Covestro.