Hypatia is the worlds first FOSS malware scanner for Android. It is powered by ClamAV style signature databases.

Features

Near zero battery impact: you'll never notice any impact on battery at all
Extremely fast: it can scan small files (1MB) in <20ms, and even large files (40MB) in 1000ms.
Memory efficient: with the default databases enabled it uses under 120MB.
Regular scan: allowing selection of /system, internal storage, external storage, and installed apps
Realtime scanner: can detect mal