A method for the amplification and analysis of nucleic acid sequences in a CMOS chip, the method comprising: a. taking a system having a liquid volume in contact with a surface of the CMOS chip wherein the liquid volume contains a nucleic acid sample, two or more non-immobilised amplification primers and reagents for nucleic acid amplification, and the chip surface has one or more immobilised amplification primers; b. performing a nucleic acid amplification reaction using the non-immobilised amplification primers to produce a first non-immobilised nucleic acid amplification product; c. further amplifying the first non-immobilised nucleic acid amplification product using the one or more immobilised amplification primers to produce an immobilised second nucleic acid amplification product; d. either i. interrogating a localised signal generated at the immobilised second nucleic acid amplification product location in real time or ii. removing the liquid volume and first non-immobilised amplification product and replacing with a new liquid volume having a primer which hybridises to the immobilised second nucleic acid amplification product, and either; 1. directly detecting the hybridised primer or 2. flowing over the immobilised second amplification product a solution comprising at least one species of nucleotide in order to extend the hybridised primer, and e. detecting using the CMOS chip, the presence, absence or sequence of the second nucleic acid amplification product. a. taking a system having a liquid volume in contact with a surface of the CMOS chip wherein the liquid volume contains a nucleic acid sample, two or more non-immobilised amplification primers and reagents for nucleic acid amplification, and the chip surface has one or more immobilised amplification primers; b. performing a nucleic acid amplification reaction using the non-immobilised amplification primers to produce a first non-immobilised nucleic acid amplification product; c. further amplifying the first non-immobilised nucleic acid amplification product using the one or more immobilised amplification primers to produce an immobilised second nucleic acid amplification product; d. either i. interrogating a localised signal generated at the immobilised second nucleic acid amplification product location in real time or ii. removing the liquid volume and first non-immobilised amplification product and replacing with a new liquid volume having a primer which hybridises to the immobilised second nucleic acid amplification product, and either; 1. directly detecting the hybridised primer or 2. flowing over the immobilised second amplification product a solution comprising at least one species of nucleotide in order to extend the hybridised primer, and i. interrogating a localised signal generated at the immobilised second nucleic acid amplification product location in real time or ii. removing the liquid volume and first non-immobilised amplification product and replacing with a new liquid volume having a primer which hybridises to the immobilised second nucleic acid amplification product, and either; 1. directly detecting the hybridised primer or 2. flowing over the immobilised second amplification product a solution comprising at least one species of nucleotide in order to extend the hybridised primer, and 1. directly detecting the hybridised primer or 2. flowing over the immobilised second amplification product a solution comprising at least one species of nucleotide in order to extend the hybridised primer, and e. detecting using the CMOS chip, the presence, absence or sequence of the second nucleic acid amplification product.