The thick-set, bearded 55-year-old was back in the headlines this week when he left his house for the first time in a year without having to report his whereabouts to police. He used his new-found freedom to tell the media he had been informed by police that, in addition to an ongoing tax evasion case, he was suspected of other crimes including pornography, bigamy and illicit exchange of foreign currency. Ai, China\'s most prominent critic whom authorities are desperate to silence, is barred from travelling, although the less he goes abroad, the more, it seems, he matters. \"It\'s certainly true that it (the crackdown) has the unintended effect outside of China,\" said Patrick Griffith of Freedom Now, a U.S.-based campaign group representing prisoners of conscience around the world. The group has not worked with Ai but represents Liu Xiaobo, the Nobel Laureate jailed for 11 years for inciting subversion. \"He\'s almost universally known in the States not only because of his art, which he was fairly well known for, but for his disappearance last year which launched him to international stardom,\" Griffith added. Ai was held for 81 days without charge in 2011, mainly in solitary confinement, until his conditional release. Chinese authorities may well be aware of the impact of their actions abroad, but see it as a necessary trade-off for limiting the audience at home for Ai\'s critique of everything from politics and corruption to pollution and education. \"They are very scared of this information getting out,\" said Griffith. \"To some extent they\'ve been successful. (But) people are increasingly aware of Ai Weiwei and his message. Internet activists are able to get around the \'great firewall\'.\" ART A-LISTER There is little doubt Ai\'s outspoken views and subsequent travails have placed him at the \"high table\" of contemporary art in the West, although many of his works are not overtly political and their conceptual nature limits their market value. \"In terms of his impact, it makes him an even more important artist,\" said Anders Petterson, head of ArtTactic which analyses trends in the art market, commenting on the latest headlines. \"This is going to reignite interest in him among non-mainland Chinese collectors, and I guess we will see collectors and art institutions rallying around him.\" In October Ai was named the art world\'s most powerful figure in the ArtReview magazine\'s ranking, topping familiar names like gallery owner Larry Gagosian and renowned artists including Gerhard Richter (who ranked 11th) and Damien Hirst (64th). He has exhibited in Britain, the United States, France, Germany, Switzerland and beyond in recent years, and, while he cannot always be present due to travel restrictions, he enjoys a strong following among critics and the public. One notable triumph was his \"Sunflower Seeds\", part of the Unilever Series staged in the cavernous Turbine Hall of London\'s Tate Modern museum. The 2010 work consisted of 100 million handmade porcelain \"seeds\" spread out across the floor. Like much of his conceptual work, the piece could be interpreted both as a critique of China and a broader commentary on issues facing society today - a sea of faceless individuals trampled into dust; mass production versus artistry. It certainly caught collectors\' imagination. In May, a one-ton batch of the seeds, which can be arranged in any shape, fetched $782,500 at Sotheby\'s in New York, an auction record for Ai. While significant, Ai\'s commercial value pales in comparison to other Chinese contemporary artists, and prices for his works have not skyrocketed in the same way. Before this year, his auction record stood at $657,000 for \"Chandelier\" set in 2007. By comparison, the contemporary Chinese auction high is held by Zhang Xiaogang, whose \"Forever Lasting Love\" sold for just over $10 million at Sotheby\'s in Hong Kong in April 2011. \"One issue is the medium,\" said Petterson. \"Ai\'s practice is very much working with architecture, ceramics, furniture. It is very difficult to put his work in a single \'box\'. \"That doesn\'t lend itself so much to the commercial market. The other leading Chinese contemporary artists are mainly straight painters.\" Another factor may be that mainland Chinese collectors, who have driven contemporary art prices to record highs in recent years, may be wary of investing in an artist who is viewed with such mistrust by the authorities. HEAD-ON CHALLENGE That mistrust comes from Ai\'s decision to challenge the Communist Party head on. After co-designing the famous \"Bird\'s Nest\" stadium in Beijing for the 2008 Games, he likened China\'s embrace of the Olympics to a \"pretend smile\" which he found \"disgusting\", and refused to attend the opening ceremony. Asked what China was trying to hide, Ai said: \"There are too many things. The whole political structure, the condition of civil rights ... corruption, pollution, education, you name it.\" In 2008 he also challenged the authorities to properly investigate the deaths of thousands of children in a devastating earthquake in Sichuan, southwest China, amid suspicion that schools had been poorly constructed in part due to corruption. Author Hari Kunzru called it a \"turning point, when this provocateur and prankster became a genuine threat to the Chinese state.\" In 2009 Ai created \"Remembering\", a wall of thousands of bright colored backpacks in Munich that spelled out the words of a mother of a quake victim describing her daughter: \"She lived happily for seven years in this world.\" Few of his works are so overtly political, but through thought-provoking, often playful art he examines how the past can be trampled in the rush for modernity, freedom within society, mass production and consumption and the value of art. Ai\'s father was Ai Qing, a poet revered in China but also denounced as a \"rightist\" in the 1950s and sentenced to hard labor in a remote region of Xinjiang where his son was raised. The artist left China for the United States in 1981 where he stayed mostly in New York for 12 years, a period that had a huge influence on his career. In 1993 he returned to his homeland, where, for the moment, he is stuck. Ai said the support and help he received while in detention had given him hope. \"Stupidity can win for a moment, but it can never really succeed because the nature of humans is to seek freedom,\" he wrote in the Guardian newspaper on Thursday. \"They can delay that freedom but they can\'t stop it.\"