A set of signal amplification sandwich structures for amplifying, detecting and/or quantifying the level of a group of target analytes selected from cells, bacteria, protozoa, fungi, virus particles, proteins, peptides, enzymes, hormones, haptens, cancer markers, nucleic acids, genes, oligonucleotides, DNA, RNA, small molecules, drugs, pesticides, organic chemicals, industrial chemicals and compounds in a fluid sample, wherein each of said structures consists of: (a) a first outer layer comprising a magnetic particle conjugated with a plurality of a first analyte binding material for binding an analyte; wherein the magnetic particle is associated with a group of multiple target analytes or wherein the magnetic particle is associated with a specific analyte (b) an inner layer comprising the analyte; and (c) a second outer layer comprising a nonmagnetic particle conjugated with a plurality of a second analyte binding material for binding the analyte that is a matched pair with the first analyte binding material, and the nonmagnetic particle is also conjugated on its outer structure or temporarily filled in its inner structure with a plurality of an electrochemically detectable oligonucleotide tag in greater amounts than the bound associated analyte, wherein: (i) said electrochemically detectable oligonucleotide tags are for signal amplification, wherein the majority of the nucleotides within said oligonucleotide tags are guanine, wherein the nucleotides within the oligonucleotide tags are selected from the group consisting of guanine, adenine, and thymine, and wherein the combination of said nucleotides produces a unique oligonucleotide tag that is used to amplify, detect and/or quantify a specific analyte or group of specific analytes; (ii) analyte amplification performance of said signal amplification sandwich structure can be tuned to meet the desired limit of detection by adjusting one or more of the following parameters: (a) the number of electrochemically detectable oligonucleotide tags per nonmagnetic particle; (b) the number of guanines per electrochemically detectable oligonucleotide tag; (c) the size of the nonmagnetic particle; and (d) the surface area of the nonmagnetic particle for conjugating electrochemically detectable oligonucleotide tags; (iii) the number of electrochemically detectable oligonucleotide tags per nonmagnetic particle ranges from 10 2 to 10 13, the number of guanines per electrochemical detectable oligonucleotide tag ranges from 10 to 400, wherein the nonmagnetic particles are spherical and/or nonspherical, the diameter of spherical nonmagnetic particles ranges from 1 to 400 micrometers, the surface area of nonspherical nonmagnetic particles has an equivalent surface area of spherical nonmagnetic particles with ranges from 1 to 400 micrometers, and the surface of the nonmagnetic particles is smooth, rough, porous, or extended with attachments to other nonmagnetic particles; and (iv) no optically detectable tags are used for amplification, detection or quantification. (a) a first outer layer comprising a magnetic particle conjugated with a plurality of a first analyte binding material for binding an analyte; wherein the magnetic particle is associated with a group of multiple target analytes or wherein the magnetic particle is associated with a specific analyte (b) an inner layer comprising the analyte; and (c) a second outer layer comprising a nonmagnetic particle conjugated with a plurality of a second analyte binding material for binding the analyte that is a matched pair with the first analyte binding material, and the nonmagnetic particle is also conjugated on its outer structure or temporarily filled in its inner structure with a plurality of an electrochemically detectable oligonucleotide tag in greater amounts than the bound associated analyte, (i) said electrochemically detectable oligonucleotide tags are for signal amplification, wherein the majority of the nucleotides within said oligonucleotide tags are guanine, wherein the nucleotides within the oligonucleotide tags are selected from the group consisting of guanine, adenine, and thymine, and wherein the combination of said nucleotides produces a unique oligonucleotide tag that is used to amplify, detect and/or quantify a specific analyte or group of specific analytes; (ii) analyte amplification performance of said signal amplification sandwich structure can be tuned to meet the desired limit of detection by adjusting one or more of the following parameters: (a) the number of electrochemically detectable oligonucleotide tags per nonmagnetic particle; (b) the number of guanines per electrochemically detectable oligonucleotide tag; (c) the size of the nonmagnetic particle; and (d) the surface area of the nonmagnetic particle for conjugating electrochemically detectable oligonucleotide tags; (iii) the number of electrochemically detectable oligonucleotide tags per nonmagnetic particle ranges from 10 2 to 10 13, the number of guanines per electrochemical detectable oligonucleotide tag ranges from 10 to 400, wherein the nonmagnetic particles are spherical and/or nonspherical, the diameter of spherical nonmagnetic particles ranges from 1 to 400 micrometers, the surface area of nonspherical nonmagnetic particles has an equivalent surface area of spherical nonmagnetic particles with ranges from 1 to 400 micrometers, and the surface of the nonmagnetic particles is smooth, rough, porous, or extended with attachments to other nonmagnetic particles; and (iv) no optically detectable tags are used for amplification, detection or quantification.