Physical and chemical sensing enables detection of functional states of individual end organs for state- dependent neuromodulation. NEST 5 focuses on developing robust sensors for temperature, motility, pH, acetylcholine, and catecholamines, and performing extensive benchtop testing to ensure reliable in vivo performance for end organ sensing. Proper functioning of end-organs is dependent on the local organ temperature. Therefore, accurate, in vivo temperature sensing of end organs can provide valuable information on their functional states. We will develop micropatterned platinum thin film-based resistive temperature sensors encapsulated in Parylene C for in vivo temperature sensing. Motility of certain end organs is associated with their functional states such as esophagus expansion and sphincter contraction. We will develop resistive and capacitive strain sensors encapsulated in Parylene C or polyurethane for motility sensing of target end organs. We will conformally coat commercial bend sensors with Parylene C as encapsulation and suture them in a pre-bent configuration to convert contraction and expansion to bending deformations. In parallel, we will conformally coat a commercial stretchable capacitive sensor with polyurethane as stretchable encapsulation. Acetylcholine functions both as a neuromuscular transmitter and neuromodulator, and is found in the central and peripheral neurons, in target organs of the parasympathetic nervous systems. NEST 5 develops electrochemical acetylcholine sensor using an enzyme-free sensing membrane doped with an organic and stable receptor. We will integrate the sensing membrane in a Parylene-C based platinum microarray. The end-organ electrochemical sensing of pH can be used for detecting functional states of individual end organs for enabling state-dependent neuromodulation. We will develop a platinum microarray on a Parylene substrate and electrodeposit iridium oxide as the active pH sensing material. The end-organ electrochemical sensing of catecholamines, and norepinephrine (NE) in particular, can be used for detecting the efficacy of autonomic neuromodulation on restoring the sympathetic-parasympathetic balance, as well as functional or disease states in organs and the body. We will develop a platinum microarray on a Parylene substrate and detecting catecholamines using the established methodology of fast scan cyclic voltammetry. Extensive thermally accelerated benchtop testing will be performed in saline for all sensing modules to de-risk the technology for long-term end organ sensing. Electrochemical sensing modules will be tested pooled serum media (in addition to saline solutions) for evaluation of sensor biofouling.