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A micro-capillary electrophoresis (μCE) system is one of the widely adopted techniques in the molecular diagnostics and DNA sequencing due to the benefits of high resolution, rapid analysis, and low reagent consumption, but due to the requirements of bulky high-power suppliers and an expensive laser-induced fluorescence detector module, the conventional set-up of μCE system is not adequate for point-of-care (POC) molecular diagnostics. In this study, we constructed a miniaturized and integrated μCE system which can be manipulated by a smartphone. The smartphone not only powers two boost converters and an excited laser, but also controls the relay for the power switch. Moreover, the complementary metal-oxide-semiconductor (CMOS) camera of the smartphone was used for detecting the fluorescence signal of amplicons amplified with reverse transcription-polymerase chain reaction (RT-PCR). We also developed a web-based application so that the raw data of the recorded fluorescence intensity versus the running time can display typical capillary electropherograms on the smartphone. The total size of the hand-held μCE system was 9.6 cm [Width] × 22 cm [Length] × 15.5 cm [Height], and the weight was ∼1 kg, which is suitable for POC DNA testing. In the integrated smartphone-associated μCE system, we could accurately analyze two genes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), namely N gene and S gene along with two bracket ladders in 6 min to identify SARS-CoV-2. Such an advanced μCE platform can be applied for a variety of on-site molecular diagnostics fields with user-friendliness.

Due to the requirement of high-voltage power supply, on-chip micro-capillary electrophoresis (μCE) suffers from practical on-site bioapplications. In this paper, we introduced a smart phone based electric power system for μCE on a chip with simple electrical operations and improved portability of a μCE device. Since the power of the smart phone is limited to 5 V, we utilized a boost converter circuit to increase up to 250 V, which enables μCE on a chip. The typical μCE channel with a cross design was patterned on the PMMA substrate, and the sample, the waste, the anode and the cathode reservoirs were fabricated. Two steps of μCE consisting of the injection and the separation were performed to separate two amplicons (121 bp FliC gene of Escherichia coli and 161 bp InvA gene of Salmonella serovar Typhimurium). During the injection step, the voltages applied in the sample and waste reservoirs were 0 V and 250 V, respectively, and the amplicons were filled in the injection channel (6.8 mm length) in 50 s. We switched the power supply to the anode reservoir with 250 V and the cathode reservoir with 0 V. Two amplicons were successfully separated in the separation channel (17 mm length) in 4 min. In order to assign the peak in the electropherogram, we added two bracket ladders with the amplicon sample, so that we could accurately identify the target peak based on a relative migration time.