Well, LIGO detected the merger of 2 neutron stars
Their masses were estimated to be 1.37 +/- 0.2 solar mass.
The least massive black holes detected so far by LIGO have masses of 7 and 7.5 solar mass.
The gravitational wave teams periodically take breaks to work on upgrading the sensitivity of their interferometers. In time the sensitivity will be sufficient to detect smaller mass black hole mergers. The time frame for when they might get down to 0.145 solar mass is hard to predict. However the ability to detect the merger of an 0.145 solar mass BH with a high mass BH may not be all that far off.
Also, NASA is considering the LISA Project which would involve an interferometer orbiting in space and free of Earth’s noisy environment. If this project is funded, it would probably be able to detect the the smallest black holes we have discussed. Here is a link to their website: