Fig. 4

Imprecision evaluation of the OTC activity testing system. a The OCT activity detected after 1-h reaction time, n = 20. b The OCT activity detected after 3-h reaction time, n = 20. c The OCT activity detected after 1-h reaction time, repeated 4 times with 20 points each time. d The OCT activity detected after 3-h reaction time, repeated 4 times with 20 points each time