Developers of today's medical instruments must comply with the electrical safety standards that are required when medical devices come into contact with a patient. Devices such as blood pressure monitors, ultrasound, endoscopes and borescopes, for example, must adhere to the International Electrotechnical Commission's IEC 60601-1 Type BF ("Body Floating") standard since these instruments have conductive contact with the patient.
To build such instruments, the electrical components -such as a borescope camera - that come into contact with the patient must be electrically isolated and separated from earth to minimize the amount of leakage current that may occur.
Luckily, developers of products such as borescopes and rigid/ flexible endoscopes can now take advantage of off-the-shelf components that can be used to perform this task. In the development of its coreVIEW series of remote head camera inspection controllers for borescopes and endoscopes, for example, Zibra Corp (Westport, MA, USA; www.zibracorp.com) turned to NET USA (Highland, IN, USA; www.net-usa-inc.com) to assist in the design of these products.
"What the developers of coreVIEW required was a modular system that could be adapted to be used with a number of different cameras while at the same time adhering to the IEC 60601-1 Type BF standard," says Milo Obradovic, Chief Operating Officer at NET USA. "At the same time, the remote camera head was required to be as small as possible to allow other miniaturized surgical instruments to be used in conjunction with them."
To accomplish this, NET developed a remote camera that integrates the NANEYE, a 250 x 250 pixel CMOS imager from AWAIBA (Madeira, Portugal; www.awaiba.com), a sensor measuring 1mm x 1mm with integrated optics. Digital data from the CMOS imager is first transferred to a camera main board. Here, an FPGA is used to perform such functions as dead pixel correction, white balance and color adjustment.
Serial data is then transferred to a system controller board. To adhere to the IEC 60601-1 Type BF standard, this data is then galvanically isolated. Similarly, the 5V/1A used to power the controller board is galvanically isolated from the circuitry on the board. An on-board microcontroller then allows the user to perform such tasks as image zoom and image rotation.
To view images, the system controller board features an HDMI output that allows images to be displayed on a monitor up to 25ft from the unit. To store image data, the board also features a USB 3.0 port that allows images to be transferred to a remote PC.
According to Obradovic, NET USA now offers the camera controller board and system controller board as a development kit. "Because of the modular nature of the system," he says, it can be customized for other applications that require camera heads and galvanically isolated controllers."
