The effectiveness of biological implants is naturally limited by power constraints. Batteries need to be charged, and if it is runs out, it could seriously ruin one's day.
New experimental techniques enable the harvesting of ambient energy (warmth, movement, blood sugar) within the body to power implants, in this case a pacemaker, entirely endogamously.
This gives peace of mind to many, especially those who venture off the beaten track. It also illustrates how we may continue to blend medical, assistive, and informative technologies with the human body.