** Shares of Atomo Diagnostics AT1.AX rise as much as 13.5% to A$0.042, their highest level since January 5

** Stock logs its biggest intraday pct gain since January 2

** The medical device firm secures purchase order for A$502,000 ($335,386.20) worth of HIV self-tests

** Adds that supply order is for an African country

** Stock set for a third consecutive session of gains, if current momentum persists

** Stock up nearly 90% in 2025

($1 = 1.4968 Australian dollars)

(Reporting by Rajasik Mukherjee in Bengaluru)

((Rajasik.Mukherjee@thomsonreuters.com))