Help on Strapless continuous heart rate monitor watch?

armin3000

Dear all,
I'm doing an academic research and I need to log heart rate changes data of a person during some hours a day while he's doing his normal activities.
I need to use a strapless hrm because the data is going to be collected from +30 people and it's supposed to be in a non intrusive way for example like a typical watch, not a chest belt.
Please tell me your experiences on such devices. I know that tools with strap are more accurate but it's my research limitations. I just found ePulse2 but I don't know how exactly it works or how much is accurate.

Features that I need:
- Continuous HR monitoring for 3-4 hours
- logging time of each heart rate (X bps on hh:mm)
- Transferring and showing data on computer in a digital numerical table (like an Excel sheet with Heart rate and time)
- No burned calorie calculator needed.
- No GPS needed.

10%-15% error in hear rates are acceptable.

* Second request: If such device is not available or they are too buggy and unstable please introduce some strapless watches that works with finger (noncontinuous monitoring). I will tell the participants to put their finger every 10-15 minutes. Logging and transferring data into the compute are needed in this case too.

Thanks for your help,
Armin

*Sorry for English mistakes.