Does We3.toWei function accept decimal number? - ethereum

Question

I am doing some research about Web3js.
I try to build one contract that can let anyone to purchase my token by ether.
I use testrpc to build my pricate chain
Here is my transfer function
handleTransfer: function(event) {
event.preventDefault();
var amount = parseInt($('#TTTransferAmount').val()); // get the ether amout
console.log('Pay ' + amount + ' ether');
var GustavoCoinCrowdsaleInstance;
web3.eth.getAccounts(function(error, accounts) {
if (error) {
console.log(error);
}
var account = accounts[0];
App.contracts.GustavoCoinCrowdsale.deployed().then(function(instance) {
GustavoCoinCrowdsaleInstance = instance;
console.log(typeof amount );
console.log( web3.toWei(amount, "ether"));
return GustavoCoinCrowdsaleInstance.sendTransaction({ from: account, value: web3.toWei(amount, "ether")})
}).then(function(result) {
alert('Pay Successful!');
$('#TTTransferAmount').val(0);
return App.getBalances();
}).catch(function(err) {
console.log(err.message);
});
});
}
I try to use web3.toWei function to converts an ethereum unit into wei
when I type console.log(web3.toWei(1,'ether'));
The result is fine,it will return 1000000000000000000
but when I type console.log(web3.toWei(0.1,'ether'));
it will return 0
Does toWei function only accept integer?
What should I need to do if I want to use 0.1 ether to purchase token?