Engineering Medical Imaging Devices
An All-Around Design

For medical device maker SonoSite Inc., the challenge in designing its new iLook 15 and iLook 25 hand-held ultrasound devices was creating a device that was both functional for the healthcare professional and comforting to the patient.

SonoSite's iLook 25, said to be one of the world's smallest ultrasound, is used in vascular access for improved line placement of IVs.

"From a design standpoint, one of our focused areas for the design was to make a product that is non-threatening and looks like it is giving the patient the highest care possible," explains Bryan Skaar Cabatic, industrial designer, who lead in the development of the iLook medical devices.

To accomplish this, SonoSite first focused on designing the iLook devices to be both comfortable and functional for the healthcare professional. One of the first design challenges was making the hand-held device light enough for the user and also easy to use. To balance the 3-lb weight of the device, the battery was moved to the handle and to the left of where the user's hand would be during operation. Being one of the heavier components, the battery's weight counters the weight of the display. During use, the fingers support the weight behind the display.

When designing the handle of the hand-held units, Mr. Cabatic says his design team had much to consider. For example, they had to decide whether they would make right- and left-handed units, or only left-handed units. Mr. Cabatic explains, "One of the things we looked at is, how are stenographers trained traditionally? The majority of all stenographers, the types of exams, and the placement of the beds lean toward using your right hand to scan." After deciding it would not be viable to create both left-and right-handed versions, a specialized transducer was hardwired into the device for right-handed scanning.

The next step was to size the handle so that it would work with the maximum amount of users. The design team went through many iterations and came up with a design that fit 95 percent of users. The solution was a flexible pad that was created to fit smaller hands. The pad goes inside of the existing handle and allows people with smaller hands to fit comfortably. To further add comfort for the operator, the iLook 15 and iLook 25 are made from soft-touch plastics.

"The other major challenge was how to interact with the system, because you have to input patient information, choose exam types, and adjust basic things like depth and gain," says Mr. Cabatic. Traditional ultrasounds use a full keyboard to adjust the transducer and to select different modes. This requires the use of one or both hands, impeding the scanning of the patient. SonoSite wanted to create the device so the healthcare provider would not have to take his or her right hand away from the scanner to make adjustments while scanning. To accomplish this, SonoSite's internal design team went through several control ideas. One idea consisted of placing buttons on the back of the device for input; operators would control various functions with their fingers supporting the display. Another idea was for a separate system, which would require the use of the right hand and would eliminate any scanning while making adjustments.

"It became obvious," Mr. Cabatic explains, "that you could grip the system with your hand and still be able to move your thumb about." Thus, SonoSite added a directional controller (D-controller), similar to the control used on gaming pads. With the D-controller, the operator can access all of the necessary menus for use during scanning. The operator is able to access various drop-down menus and scroll through different modes. In addition to the D-controller, SonoSite included four buttons for quick control while scanning. Each button controls one function and is within reach of the thumb.

Mr. Cabatic notes that there would still be times when the healthcare professional would have to input information about the patient. For this design element, SonoSite looked to the world of PDAs for inspiration. The input display is touch-sensitive and a slot was designed to hold a stylus so that patient information can be updated on the spot via a virtual keyboard.

According to Mr. Cabatic, SonoSite was able to design the iLook 15 and iLook 25 in a small form factor because of the company's proprietary A6 chip, which reduced the number of necessary internal components. "We had proprietary chip technology, and we build our own boards, so we wanted to see where we could take it. Basically when we set out to do this project, we wanted to design the smallest portable ultrasound machine," explains Mr. Cabatic. Through the use of the A6 chip, SonoSite's designers were able to condense the 16 boards required in a traditional ultrasound device into one board with three A6 chips.

SonoSite did not only consider the comfort of the operator when designing the iLook devices, but wanted the patient to feel comfortable as well. According to Mr. Cabatic, his team designed the iLook from an all-around perspective, considering the patient's point of view as well as the doctors. "We chose colors and materials that we felt were appropriate for being in a hospital or a doctor's office, but that also have an aesthetic appeal that you can get excited about," says Mr. Cabatic. "We didn't want it to look barren." For example, instead of using "hospital white" for the device's outer casing, SonoSite used a palette of blues and grays.

The iLook's optional dock will not only charge the device's battery when not in use, but it can also be used to download images to a computer.

In the end, for SonoSite, the number one priority was the patient. "We want to make sure we address any problems because if the iLook causes medical problems with someone, then we're not doing our job," Mr. Cabatic says. "We're trying to heal people."