Wearable Device for Breast Self-Examination: Palpreast

Wearable Device for Breast Self-Examination: Palpreast

Prototypes and considerations for safety assessment

Hardware

·      Commercial parts

  • External Top: 1 Top to Art Martial Protection, ITAKI (35€)

 

  • Inflation System: 1 fabric to create 4 air compartments, 8 baloon, 4 rubber hoses, 4 t valve, 1 manometer, 1 manual air pump. (50 €)


  • Sensitive Fabric: 2 Eeonyx Textile Zebra Fabric (external layer), 1 Eeonyx EeonTex (internal layer).

 

·      Purposely designed parts

The textile pressure sensing matrix and the inflation system are contained in a stretchy top used by women for the chest protection in martial art because it covers the total shape of the breast and reaches also the axillary zone. The top has an internal pocket where a rigid protective structure is located to prevent an excessive expansion of the inflator system.
The fabric covers the breast and the inflator system, composed by four compartments of 70 mm x 80 mm each, allows the adhesion in selective way of the sensor to the breast.
The inflator system consists of an inflation bulb with related air release valve, a manometer to check the pressure, and an appropriately designed structure, using T valves, to control the air flux in each compartment.
The inflation is due to balloons inserted in each compartment and connected to the pumping system through rubber hoses.



 

Electronic &Firmware

·      Commercial parts

  • Microcontroller

Arduino DUE https://store.arduino.cc/arduino-due (35 €)

  • Electrical components

4 Resistor 10 kOhm (0,20 cent.)

  • Software

Arduino IDE https://www.arduino.cc/en/Main/Software

·      Purposely designed parts

The acquisition electronics, based on Arduino DUE board, is designed to sequentially select all the taxels of the matrix and to measure their electrical resistance: rows are selected by sequentially providing the Vcc (3.3 V) using the Digital Ports of the microcontroller, while the 4 columns are identified through 4 different Analog Ports.
 
The resistive change related to the applied force, is converted to voltage by a resistive voltage divider, with the fixed resistance of 10 kOhm, and the voltage signal is digitised by an analogue-to-digital converter (12-bit ADC) integrated in an Arduino DUE board.
 
A firmware designed with Arduino IDE is uploaded on the Arduino board and the digital values of the matrix are transmitted through the Serial Port.

Figure 7 Electronic scheme

Software

·      Existing solutions (open source)

The interface is designed by Processing https://processing.org/.
It is a flexible software for learning how to code within the context of the visual arts, to create device graphical interface.

·      Purposely designed parts

A firmware designed with Arduino IDE is uploaded on the Arduino board and the digital values of the matrix are transmitted through the Serial Port. An appropriate interface, designed with Processing, is used to interpret the pressure magnitude through a matrix system of red colour scale that replicates the sensor’s matrix structure.
If the string value is less than the value indicated as the minimum difference, the "no abnormality" screen appears. Otherwise the "Probable defect" screen appears with a matrix system of red colour scale.

Figure 8 Software implementation

System integration and instructions for fabrication of final prototype

Hardware

  • The external top is a one piece.
  • The inflation system is composed by:
    • 4 T-valves connected in series with the air pump and manometer at the respectively ends.
    • Rubber hoses connect valves to the balloons.
    • A properly designed fabric presents 4 boxes respectively overlapping on the 4 quadrants of the breast
    • The balloons are insert in a properly designed fabric in order to create air compartments.
  • The Sensing matrix: A continuous layer of piezoresistive textile is placed between two fabric layers having custom designed highly conductive patterns. The top and bottom conductive patterns are perpendicular. Each intersection between a row (top layer) and a column (bottom layer) represents a sensing elements (taxel).

Figure 9 Palpreast prototype

Figure 10 The inflator system

Figure 11 The Pressure sensing matrix

Electronic & Firmware
Connection for the ROWS
The matrix rows are connected to digital pin: 9, 10, 11, 12. 
Connection for the COLUMS
The matrix columns are connected to analogic pins: A0,A1,A2,A3 through a voltage divider with R=10 kOhm.

Through the Arduino DUE board the results of the analog reading are converted to 12-bit digital values and averaged over three output values for a robust result. 

Figure 12 Read circuit for the taxels

Software
Processing can generate an exe file that run on pc without installation.
 
As seen in the previous section (Conceptual design) Palpreast is composed by different layers. 
The pockets of inflator system and the pressure sensing textile are sewn together inside the stretchy top.
8 crocodile clip cables connect the rows and columns to Arduino DUE, like as seen in electronic section. 
The Arduino USB cable is connected to the PC.