MediPi Patient Device Build Instructions and Electromagnetic Conformance Testing
The MediPi Patient device is built using a Raspberry Pi with a touch screen display within a plastic enclosure. Although the Raspberry Pi, the screen and the power supply have individually been tested by the Raspberry Pi Foundation against the Electromagnetic Conformance specification, the unit as a whole has not been. Additionally, the standard for electromagnetic radiated emissions for electronic equipment which will be used for patients who may be using sensitive medical devices such as pacemakers is higher.
The biggest issues we had were controlling the Raspberry Pi unit's electromagnetic emmissions, which uncontrolled were too high. Controlling measures were iteratively taken and re-tested. This was a time consuming process as each iteration could take >1hr. Controlling measures included ferrite sleeves, shortening of excess cables and copper tape sheilding - see guide below. The final solution could probably be improved upon with more time.
Here are the 30MHz-1GHz improvements that were made:
Electromagnetic Conformance Testing was carried out at York EMC Services, taking 5 days.
EN60601-1-2:2007 + Corr.20
** Medical electrical equipment - Part 1: general requirements for safety. Section 1.2 Collateral Standard: Electromagnetic Compatibility – Requirements and tests.**
As tested by York EMC Services on 7th-21st April 2017
Test Reports and Certificates:
Electromagnetic Conformance (EMC) Test Report
Electromagnetic Conformance (EMC) Test Cerificate
This guide instructs how to construct a Raspberry Pi Device which will conform to the following specifications:
Component list
- RPI3-MODB-16GB-NOOBS Raspberry Pi 3 Model B & 16GB MicroSD card preloaded with NOOBS for the Raspberry Pi
- RASPBERRYPI-DISPLAY Raspberry Pi 7" Touch Screen Display with 10 Finger Capacitive Touch
- STONTRONICS T6090DV Power Supply, Raspberry Pi 3 Model B, UK Euro, 5V, 2.5A
- MULTICOMP CBRPP-TS-BLK/WHT Dev Board Enclosure, Raspberry Pi 7" Touch Screen with Pi B+ or Pi 2 Boards, Polystyrene
- Wurth Elektronik Conductive Copper Tape, 20mm x 33m - ~1metre required
- Wurth Elektronik Ferrite Ring EMI Suppression Axial Ferrite Bead X2
- Wurth Elektronik Openable Ferrite Sleeve, 35.1 x 21.7 x 18.2mm, For General Application, Safety Relevant Application
- Wurth Elektronik 4 W 620 Ferrite Sleeve, 16 wires maximum, Inner dimensions:23 x 1.5mm
- Advance Tapes AT7 Black PVC Electrical Insulation Tape, 19mm x 33m, 0.15mm Thick ~50cm required
- 10cm Dupont Jumper Wire GPIO Cable Female-Female x2