1, IOUs can be valid without fingerprints. There is no fingerprint on the debit note, but it is valid with the debtor's autograph.

2. According to the law, IOUs should be in written form, and the contents of IOUs generally include terms such as type, currency, purpose, amount, interest rate, term and repayment method. Therefore, the IOU is valid as long as it contains the above provisions and is signed by the debtor.

3. Legal basis: Civil Code of People's Republic of China (PRC).

Article 667 stipulates that a loan contract is a contract in which the borrower borrows money from the lender, repays the loan at maturity and pays interest.

Article 668 stipulates that a loan contract shall be in written form, unless otherwise agreed between natural persons. The contents of a loan contract generally include terms such as loan type, currency, purpose, amount, interest rate, term and repayment method.

Second, whether the prenuptial agreement is valid only by signature and not by fingerprint.

A prenuptial agreement is valid only if it is signed without fingerprints, as long as other valid conditions are met. According to the legal provisions of the Civil Code, if a written agreement does not violate the legal provisions and can reflect the true meaning of both parties to the agreement, the contract is established and takes effect when both parties sign, seal or press their fingerprints. Unless otherwise provided by law or agreed by the parties.