steady-state value after fast medium change) of 32 ms was mea-sured as response to a step function from 100% oxygen to 100%nitrogen and vice versa. For a polymer film based sensor with com-parable signal intensity the respective response times amount to2.2 s and 4 s, respectively. Thus, the electrospun sensors exhibit asignal response which is accelerated by two orders of magnitude,while maintaining the sensitivity and other optical characteristics.In experiments with electrospun nanofiber layers of various thick-nesses no changes of response times were found. This demonstratesunrestricted diffusion of oxygen molecules through the void vol-ume of the highly porous 3D membrane. The actual diffusion pathresponsible for the response times is prevailingly determined bythe nanofiber diameter but scarcely by the overall thickness of thenanofiber layer. It shall be noted that 32 ms may actually be consid-ered the upper limit of the response time t90of electrospun sensors;electronic (e.g. sampling rate) as well as physical limitations (e.g.ultra-fast atmosphere change) can lead to a substantial increase ofthe response time in this time regimes.