Design of Pulse Oximeter Solution for Conscious Rodents

Neuromodulation can be used to control organ function through exogenous augmentation of neural activity via targeted delivery of an electrical stimulus. Recently, neuromodulation has been a topic of investigation to treat many illnesses and conditions including Parkinson’s disease, epilepsy, obesity, chronic pain, type 1 diabetes, and hypertension. During neuromodulatory treatments, it is important to measure both the physiological response of the target system as well as any off-target systems that may be engaged from the delivered stimulus. Stimulation of the vagus nerve, a common target of neuromodulatory therapies, causes a vasovagal response which results in decreased cardiac rate and arteriolar dilatation. It is possible to measure these physiological parameters in anesthetized rats, but it is a challenge in conscious, moving rats because of motion artifact introduced to the sensors. By creating a noninvasive, stabilized pulse oximeter that measures the blood oxygenation waveform, one can analyze the heart rate in awake behaving animals. This study reports the design of a heart rate monitor used to monitor effects of heart rate variability during neuromodulation experiments. Design of this device included testing different sensors, methods of attaching to the rodent, microcontrollers, and wireless communication modules.