Low-Cost DSP System Design for a Handheld Biomarker Detection Device

This paper discusses a low-cost, compact, digital signal processor (DSP)-based fluorescence spectroscopy measurement device which can be used to characterize fluorescent materials. Using a precision-pulsed UV emitter and a high-speed photo-multiplier tube, a sub-nanosecond signal is generated which contains fluorescence decay information. To uniquely identify a substance, this signal must be effectively sampled at speeds in the neighborhood of 10 GHz or more. To accomplish this, a novel swept delay design using a distributed successive approximation routine was implemented on a Texas Instruments DSP. This DSP coupled with other supporting hardware comprise this undersampling digitizer, which was successfully used to measure the lifetime of several material specimens at a 10 GHz sampling rate. These results are presented in this paper.