Microcamera is as small as a grain of salt

Traditionally endoscopes used to identify tumours are often expensive and because of their multiple usages have to be put through time consuming and exhaustive cleaning procedures. The new microcamera designed at the Fraunhofer Institute for Reliability and Microintegration in Berlin can be produced inexpensively so doctors can dispose of endoscopes after using them only once. Digital camera systems consist of two components: a lens and a sensor that transforms the image into electrical signals. Electrical contacts on the sensor allow access to these signals and the information of the image. Due to the way they are manufactured, these contacts are located between the sensor and the lens. The sensors are manufactured simultaneously in large numbers, like computer chips. Fraunhofer researchers have streamlined this process of accessing electrical contacts located between a digital camera's lens and the sensor. Martin Wilke, a scientist at the Fraunhofer Institute for Reliability and Microintegration, said: "You have to think of a book full of postage stamps where many thousand stamps are printed in one step. If you want to use them, you have to separate one from another. Instead of a sheet of paper, with image sensors you have a circular disc of silicon that is known as a wafer." About 28,000 image sensors fit onto one wafer and until recently, each one was sawed out, wired and mounted on the lens that was still missing. That means wiring them 28,000 times and mounting them just as often. The new wiring process is faster and the entire camera system is smaller. According to Wilke, instead of reaching the contacts of each individual image sensor via the side, the researchers do this simultaneously, with all sensors via their reverse side while they are still connected as a wafer. This removes the need to mount individual lenses and enables them to be connected with the image sensor wafers as lens wafers. Only then is the stack of wafers sawed apart into individual microcameras. The new microcamera is small enough for the tip of the endoscope and has a resolution of 62,500 pixels. It transmits the image information through the endoscope via an electrical cable and, at 1 x 1 x 1mm, is as small as a coarsely ground grain of salt. The research is being undertaken with Awaiba and with the support of the Fraunhofer Institute for Applied Optics and Precision Engineering in Jena, Germany. Fraunhofer hopes to bring the disposable endoscopes to market in 2012.