Highly selective, sensitive, and rapidly responding acetone sensor using ferroelectric ε-WO_3 spheres doped with Nb for monitoring ketogenic diet efficiency

摘要

A ketogenic diet (KD) can enable more effective weight loss when performed with a portable breath acetone sensor capable of monitoring KD efficiency. However, current portable sensors-such as oxide semiconductor gas sensors-cannot selectively detect low concentrations of acetone in human breath, hindering their practical applications. Herein, we report an ultraselective and highly sensitive breath acetone sensor, established using WO_3 doped with 5-20 atom% Nb. The pure WO_3 sensor showed low gas responses (S = resistance ratio - 1) to all analytic gases, including acetone, ethanol, carbon monoxide, ammonia, hydrogen, and toluene (S = 0.1-2.1). In contrast, the 10 atom% Nb-doped WO_3 sensor exhibited a high gas response (S = 15.0 at 1 ppm) and ultrahigh selectivity to acetone over ethanol interference (response ratio = 22.3), even in highly humid conditions (relative humidity: 80 %). Moreover, the response time was as short as 4 s, and the detection limit was as low as 8.9 ppb, enabling breath acetone to be monitored in a rapid and precise fashion. The excellent acetone sensing performance of Nb-doped WO_3 sensors was then examined from diverse perspectives, including changes in porosity, surface area, oxygen adsorption, and charge-carrier concentration, and with respect to the formation of ferroelectric ε-WO_3 domains caused by Nb doping. This work will trigger development of a new class of portable breath sensors that can be used to monitor KD efficiency.