a credit card sized e-paper device that can only do sms. It could be efficient enough to be powered by a peltier chip, so no need to charge it ever. Seems perfect for the text generation
Not enough power for the RF transmission; even if you go off-network while not in use (so you can't recieve SMS), then you still end up needing to do quite a few 2W burst transmissions to get back on and send the SMS.
Also, peltier requires a temperature difference; keeping it warm in your pocket is not enough.
a credit card sized e-paper device that can only do sms. It could be efficient enough to be powered by a peltier chip, so no need to charge it ever. Seems perfect for the text generation