For detecting cancer, manual breast exams seem low-tech compared to other methods such as MRI. But scientists are now developing an "electronic skin" that "feels" and images small lumps that fingers can miss. Knowing the size and shape of a lump could allow for earlier identification of breast cancer, which could save lives. They describe their device, which they've tested on a breast model made of silicone, in the journal ACS Applied Materials & Interfaces.
Ravi F. Saraf and Chieu Van Nguyen point out that early diagnosis of breast cancer, the most common type of cancer among women, can help save lives. But small masses of cancer cells are not always easy to catch. Current testing methods, including MRI and ultrasounds, are sensitive but expensive. Mammography is imperfect, especially when it comes to testing young women or women with dense breast tissue. Clinical breast exams performed by medical professionals as an initial screening step are inexpensive, but typically don't find lumps until they're 21 millimeters in length, which is about four-fifths of an inch. Detecting lumps and determining their shape when they're less than half that size improves a patient's survival rate by more than 94 percent. Some devices already mimic a manual exam, but their image quality is poor, and they cannot determine a lump's shape, which helps doctors figure out whether a tumor is cancerous. Saraf and Nguyen wanted to fill this gap.
Toward that end, they made a kind of electronic skin out of nanoparticles and polymers that can detect, "feel" and image small objects. To test how it might work on a human patient, they embedded lump-like objects in a piece of silicone mimicking a breast and pressed the device against this model with the same pressure a clinician would use in a manual exam. They were able to image the lump stand-ins, which were as little as 5 mm and as deep as 20 mm. Saraf says the device could also be used to screen patients for early signs of melanoma and other cancers.
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More information: Tactile Imaging of an Imbedded Palpable Structure for Breast Cancer Screening, ACS Appl. Mater. Interfaces, Article ASAP. DOI: 10.1021/am5046789
Apart from texture, the human finger can sense palpation. The detection of an imbedded structure is a fine balance between the relative stiffness of the matrix, the object, and the device. If the device is too soft, its high responsiveness will limit the depth to which the imbedded structure can be detected. The sensation of palpation is an effective procedure for a physician to examine irregularities. In a clinical breast examination (CBE), by pressing over 1 cm2 area, at a contact pressure in the 70–90 kPa range, the physician feels cancerous lumps that are 8- to 18-fold stiffer than surrounding tissue. Early detection of a lump in the 5–10 mm range leads to an excellent prognosis. We describe a thin-film tactile device that emulates human touch to quantify CBE by imaging the size and shape of 5–10 mm objects at 20 mm depth in a breast model using ∼80 kPa pressure. The linear response of the device allows quantification where the greyscale corresponds to the relative local stiffness. The (background) signal from <2.5-fold stiffer objects at a size below 2 mm is minimal.