Yesterday's blast in an A&W restaurant in a shopping mall came just a few days ahead of a visit by US President George W Bush to the world's most populous Muslim nation.
Anas Raharjo, a Jakarta city police officer, said the 36-year-old suspect had begun to show signs of coming round, moving his hands and opening his eyes at one point.
''He moved his hand at about 0650IST but we haven't been able to ask him questions yet,'' Raharjo said, declining to comment on potential motives behind the incident.
The force of the bomb cracked windows in the restaurant, sending broken plates, glasses and food across the floor.
Jakarta and other parts of Indonesia have seen a number of bomb attacks by Islamic militants usually aimed at targets with Western ties, but other blasts have been linked to separatist groups or criminal activities.
In 2003, a bomb exploded near an outlet of the US-based KFC fast-food chain at Jakarta's international airport, wounding more than 10 people.
Major attacks linked to Islamic militants have mostly been in the capital or on the resort island of Bali.
A bomb attack in 2003 on the US-run JW Marriot hotel in Jakarta killed 12, while another blast outside the Australian embassy a year later killed 10.
Two sets of suicide bombings at nightclubs and restaurants popular with Western tourists on Bali in 2002 and 2005 killed more than 220.
REUTERS sp ht1235