Biological sensors

All living organisms contain biological sensors with functions similar to those of the mechanical devices described. Most of these are specialized cells that are sensitive to:

• Light, motion, temperature, magnetic fields, gravity, humidity, vibration, pressure, electrical fields, sound, and other physical aspects of the external environment
• Physical aspects of the internal environment, such as stretch, motion of the organism, and position of appendages (proprioception)
• Environmental molecules, including toxins, nutrients, and pheromones
• Estimation of biomolecules interaction and some kinetics parameters
• Internal metabolic milieu, such as glucose level, oxygen level, or osmolality
• Internal signal molecules, such as hormones, neurotransmitters, and cytokines
• Differences between proteins of the organism itself and of the environment or alien creatures

Artificial sensors that mimic biological sensors by using a biological sensitive component, are called biosensors.