There are three methods to measure heartbeat:
1. Acoustic - Using microphones or accelerometers.
2. Electrical - Using probes in contact with the chest area.
3. Optic - Using optical sensors on the fingers, earlobe, or wrist.
For a jacket, the acoustic method seems the most likely solution since it doesn't require skin contact. Ford Motor Company in the US has recently started offering heartbeat monitors in Volvo and other Ford automobiles. It works by mounting two micro-accelerometers inside the vehicle to detect vibrations. A microprocessor analyzes the signals to determine if they match the pattern of mammalian heartbeats.
A similar approach could be used on a jacket with micro-accelrometers or microphones in the jacket over the chest area. A microprocessor could then be used to analyze/filter the signals to reduce or eliminate noise from jacket movement and other outside sources.
For a jacket, the acoustic method seems the most likely solution since it doesn't require skin contact. Ford Motor Company in the US has recently started offering heartbeat monitors in Volvo and other Ford automobiles. It works by mounting two micro-accelerometers inside the vehicle to detect vibrations. A microprocessor analyzes the signals to determine if they match the pattern of mammalian heartbeats.
House_Cat, could you give a reference to more information about the automotive heartbeat sensor? Where are the microphones mounted? What does the car do with the heartbeat information one it has been acquired?
I don't know where the sensors are located. Ford didn't say in their description of the system.
They send the heartbeat information to the keychain remote of the car owner. It displays as blinking LED's. The purpose is supposed to be twofold. The first is security - you could tell if there was an intruder hiding in your car. The second is to act as a reminder for people who might have forgotten that they left a pet or child in the car.
It's a "gimmick" - but it's an interesting application of technology.
You can read about it here: **broken link removed**
Acoustic is hard to struggle with the noise. Electrode is not easy to use. a reflecting infrared senesor is a good solution, the circuit is very simple. But if there's a shirt under the jacket, it doesn't work.