Apparatus for detecting the presence, absence or level of a target molecule in a sample, the apparatus comprising: a) a first region comprising: i) a support; and ii) an immobilisation oligonucleotide; and iii) a nucleic acid molecule which has a binding affinity to a target molecule, wherein the nucleic acid molecule is configured to form a complex with the target molecule, wherein the immobilisation oligonucleotide is attached directly or indirectly to the support, and further wherein the immobilisation oligonucleotide comprises a nucleic acid sequence which is at least partially complementary to a nucleic acid sequence of the nucleic acid molecule and wherein the nucleic acid molecule is capable of hybridizing to the immobilisation oligonucleotide and further wherein the nucleic acid molecule is capable of being displaced from the complex with the immobilisation oligonucleotide if the target molecule is present in the sample; the apparatus further comprising: b) a further region comprising: i) a support; and ii) a capture oligonucleotide attached directly or indirectly to the support, wherein the capture oligonucleotide comprises a nucleic acid sequence which is at least partially complementary to a nucleic acid sequence of the nucleic acid molecule, wherein the capture oligonucleotide is configured to hybridize to the nucleic acid sequence of the nucleic acid molecule when in complex with the target molecule to capture the nucleic acid-molecule-target molecule complex thereby enabling the presence or level of the target molecule to be detected. a) a first region comprising: i) a support; and ii) an immobilisation oligonucleotide; and iii) a nucleic acid molecule which has a binding affinity to a target molecule, wherein the nucleic acid molecule is configured to form a complex with the target molecule, wherein the immobilisation oligonucleotide is attached directly or indirectly to the support, and further wherein the immobilisation oligonucleotide comprises a nucleic acid sequence which is at least partially complementary to a nucleic acid sequence of the nucleic acid molecule and wherein the nucleic acid molecule is capable of hybridizing to the immobilisation oligonucleotide and further wherein the nucleic acid molecule is capable of being displaced from the complex with the immobilisation oligonucleotide if the target molecule is present in the sample; the apparatus further comprising: i) a support; and ii) an immobilisation oligonucleotide; and iii) a nucleic acid molecule which has a binding affinity to a target molecule, wherein the nucleic acid molecule is configured to form a complex with the target molecule, b) a further region comprising: i) a support; and ii) a capture oligonucleotide attached directly or indirectly to the support, wherein the capture oligonucleotide comprises a nucleic acid sequence which is at least partially complementary to a nucleic acid sequence of the nucleic acid molecule, wherein the capture oligonucleotide is configured to hybridize to the nucleic acid sequence of the nucleic acid molecule when in complex with the target molecule to capture the nucleic acid-molecule-target molecule complex thereby enabling the presence or level of the target molecule to be detected. i) a support; and ii) a capture oligonucleotide attached directly or indirectly to the support, wherein the capture oligonucleotide comprises a nucleic acid sequence which is at least partially complementary to a nucleic acid sequence of the nucleic acid molecule, wherein the capture oligonucleotide is configured to hybridize to the nucleic acid sequence of the nucleic acid molecule when in complex with the target molecule to capture the nucleic acid-molecule-target molecule complex thereby enabling the presence or level of the target molecule to be detected.