Low-Cost, Handheld Tactile Imaging Device for Breast Cancer Screening - Palpation has been routinely used by physicians to diagnose diseases for centuries. In Clinical Breast
Examination (CBE), medical personnel screen for suspect lesions (that are 10- to 20-fold stiffer than
surrounding tissue) by palpation using two or three fingers followed by precession about a fixed 1-2 in2 contact
area. Typical pressure to avoid discomfort and also feel deeper palpable objects ranges from 40-90 KPa.
However, palpation is highly qualitative and subjective; and it is not possible to follow progression in the
morphological changes. The goal of the proof-of-concept study is to develop an ergonomic, low cost (less than
$5) stethoscope-like probe to capture tactile images during palpation. The probe will be pressed at 30-90 KPa
pressure and a series of images will be recorded in real time by pivoting the probe over a fixed contact area of
about 1-2 in2 in a precession motion similar to CBE. The studies will be performed over a well-characterized
physical model, an artificial breast, and a clinical test on humans. The tactile image would be at a resolution of
~100 µm to image =5 mm features at 20-30 mm depth from the surface with relative hardness of =10-fold
compared to the surrounding matrix. Two key drivers for developing the technology are: (i) digitizing CBE will
offer a screening record between biannual mammogram exams, for women below 40, and in low-income
countries where accessibility to a mammogram is limited; and (ii) the current digital CBE instruments (with
array of 1 mm size sensors compared to proposed 100 µm size pixels) require rubbing the device on the skin
at constant pressure and speed to create an image by stitching together the frames, potentially causing
distortions/smearing due to dynamics of the palpable features. The grayscale of the image for the proposed
device will be linear making the analysis quantitative to detect local hardness and score and track the palpation
over time. The low power of the device will allow connectivity to a USB port for power, signal, and imaging on a
laptop computer or smart phone. To image more complex body topography, such as axillary and cervical
lymph nodes, the design will allow for interchangeable device heads of different sizes. At the heart of the
proposed device is a ~100 nm thick nanostructured film that converts pressure to electrical signal to form the
tactile image. The film is a stratified structure of a monolayer of Au nanoparticles interposed by ~5 nm thick
polymer layers. On pressing the film, the electron tunneling current between the particles modulates to
measure the local pressure. There are two specific aims: (i) develop an unpackaged device to prove the
principle in terms of resolution, sensitivity, power requirement for USB connectivity, and ability to image 10-fold
harder structures 3-10 mm in size at depths of 3-30 mm using a physical model; and (ii) develop a handheld
device for testing on artificial breast model and limited clinical study with ~50 de-identified patients with breast-
pain complaints or who are scheduled for mammograms. The preliminary and published results (by PI) indicate
that the specified resolution, sensitivity, and performance are possible. A US Patent was issued in 2010.