A Fully Integrated CMOS Fluorescence Biochip for DNA and RNA Testing

Design and successful implementation of a fully integrated CMOS fluorescence biochip for deoxyribonucleic acid (DNA)/ribonucleic acid (RNA) testing in molecular diagnostics (MDx) is presented. The biochip includes a $32 \times 32$ array of continuous wave fluorescence detection biosensing elements. Each biosensing element is capable of having unique DNA probe sequences, wavelength-selective multi-dielectric emission filter (OD of 3.6), resistive heater for thermal cycling, and a high performance and programmable photodetector. The dimension of each biosensor is $100\,\,\mu \text {m}\times 100\,\,\mu \text{m}$ with a $50 \,\,\mu \text {m}\times 50\,\,\mu \text{m}\,\,\text{N}_{\mathrm {well}}$ - $\text{P}_{\mathrm {sub}}$ photodiode acting as the optical transducer, and a $\mathrm {\Sigma \!\Delta }$ modulator-based photocurrent sensor. The measured photodetector performance shows ~116 dB detection dynamic range (10 fA–10 nA) over the 25 °C–100 °C temperature range, while being ~1 dB away from the fundamental shot-noise limit. To empirically demonstrate the compatibility of this biochip with MDx applications, we have successfully utilized the array and its thermal cycling capability to adopt a 7-plex panel for detection of six human upper respiratory viruses.