CW DOSI Probe for Cancer Monitoring

The proposed probe contains six pairs of LEDs, one photo-detector assembly and drive electronics. Each of the 12 LEDs may be selected individually, with external drive current controlling the output intensity.

The LED pairs are arranged in a circle with a 25.4mm radius, with the photodiode assembly in the center.

A single flexible, multi-conductor cable provides power and control. The HDMI cable seems like a reasonable off-the-shelf solution (with mini-HDMI type C connector on the probe)

Updated Version (2019)

This is documentation for the V3 probe design by Fraunhaufer. EDF is assisting in a new manufacturing run starting March 2019.

NOTE: The LEDs vary in whether they have an Anode polarization mark or Cathode polarization mark. Due care must be taken when preparing assembly documentation !!

The layout V3_1.1 expects one of each, so the two packages are reversed on the silkscreen.

V3_1.1 layout:

  • 850nm expect Cathode mark
  • 750nm expect Anode mark

Obsolete Versions

Initial (Rigid PCB) Design

Revised (Flex PCB) Design


  1. The 74HCT154 is attractive because of the very small package, but has active-low logic outputs. This requires a small change in the schematic. The control interface should be unchanged. Alternatively, the 4514 decoder is available in a TSSOP24 package which is about 7mm x 8mm

Interface Cable

Pinout for micro HDMI

NOTE NOTE NOTE: uHDMI and standard HDIMI pinouts are different!

Pin uHDMI Pin HDMI Pin DOSI Use Notes
1 - Hot Plug Detect/HEAC-
2 - Utility/HEAC+
3 1 TMDS Data2+ Photodiode+ Photodiode Anode
4 2 TMDS Data2 Shield Photodiode GND Shield for Photodiode signal
5 3 TMDS Data2- Photodiode- Photodiode Cathode
6 4 TMDS Data1+ LED Power Power for LEDs
7 5 TMDS Data1 Shield AGND Shield for LED power
8 6 TMDS Data1- AGND Ground for LEDs
9 7 TMDS Data0+ A1 Address 1
10 8 TMDS Data0 Shield DGND Logic GND
11 9 TMDS Data0- DGND Logic GND
12 10 TMDS Clock+ LE Latch enable
13 11 TMDS Clock Shield DGND Logic GND
14 12 TMDS Clock- DGND Logic GND
15 13 CEC A0 Address 0
16 17 DDC/CEC/HEAC Ground DGND Logic GND
17 15 SCL/DDC clock A2 Address 2
18 16 SDA/DDC data A3 Address 3
19 18 +5V power VCC Logic power (3.3V-5V)
Last modified 18 months ago Last modified on Nov 4, 2019, 12:56:52 PM