Interdigitated microelectrode array-coupled bipolar semiconductor photodiode array (IMEA-PDA) microchip for on-chip electrochemiluminescence detection

Abstract

Abstract This paper reports the design, fabrication and testing of a microchip wherein interdigitated microelectrode arrays (IMEA) were integrated with bipolar semiconductor photodiode array (PDA) chip to fabricate a highly compact embodiment for on-chip handling of solutions and electro-chemiluminescence (ECL) detection. A 12×12 micro array of photodiodes, each coupled with an interdigitated micro-electrode array (IMEA), an array of current amplifiers, and a photodiode element-addressing circuit were integrated into a single 2×2 cm2 IC chip. Each photodiode had dimensions of 300×300μm2 and the photodiode-to-photodiode dis-tance was 100μm. The chip was successfully applied to theon-chip quantification of electro-chemiluminescing probe-labeled single stranded oligonucleotides. The minimum detectable limit at signal/noise≥3 was found to be 5×10−14 moles of oligonucleotides with a sample volume as low as 5µl (i.e., 10 fmole/μl). The attractive features of the developed IMEA-PDA microchip are that a plurality of samples can be analyzed simultaneously using a chip and that for a given sample the data can be averaged from values obtained from multiple, individually addressed pixels. These in turn bring in speed and statistical confidence in analysis. The IMEA-PDA microchip system has the potential to be used as a versatile and highlycompact chemical analysis tool for chemical sensing and metrology applications.