The pulse sensor needs to be connected to the circuit. The circuit playground has 12 ENIG contacts onto which wire from the pulse sensor/other places can be soldered onto. While soldering wires onto a wires we need to keep in mind a few things

• How strong is the connection – Leads on to reliability considerations
• What is the mechanical load on the joint? How can it be relieved? (glue gun?)
• Is there a possibility of interference with other wires/signals? (parasitic capacitance, cross talk and exposed metal
• Ease of making a connection

After thinking about this, the easiest method I can think of is generous application of the cheap aliexpress solder past on the contact and hot air gun treatment to reflow and bond. This could be followed by application of hot glue for stress relief (can’t be done if the system needs to be reconfigured. Solder can be removed using a wick, but glue is much harder.

A similar method may be used for connecting the pulse board to the wires as well.