A novel electrochemical sensor based on electropolymerized ion imprinted poly (o-phenylenediamine) PoPD/electrochemical reduced graphene (ERGO) composite on glass carbon electrode (GCE) was fabricated for selective and sensitive determination of trace Cd(II) in water. ERGO was first deposited on the surface of GCE by electrochemical cyclic voltammetry (CV) scanning to enhance the electron transport activity at electrode surface. The ion imprinted polymer (IIP) of imprinted PoPD was then in situ electropolymerized on ERGO via CV scanning with oPD as functional monomer and Cd(II) ions as template, following removal of the template using electrochemical peroxidation method. The obtained imprinted PoPD/RERGO composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray energy spectroscopy (EDS) for the observation of their morphologies and components. The electrochemical behavior of the imprinted PoPD/ERGO/GCE was performed by CV and SWASV. The fabricated sensor of the imprinted PoPD/ERGO/GCE showed a good selectivity toward target Cd(II) ions in the presence of other heavy metal ions. Under the optimized experimental conditions, the sensor exhibited a good linear relationship between SWASV stripping peak values and Cd(II) concentration in the range of 1 to 50 ng/mL, with the limit of detection as 0.13 ng/mL (S/N = 3). The proposed electrochemical sensor of imprinted PoPD/ERGO/GCE was successfully applied for trace Cd(II) determination in real water samples.

This paper presents a low power wideband dB-linear analog baseband (ABB) circuit for a millimeter-wave (mmW) wireless receiver in 40 nm CMOS technology. The proposed ABB system consists of a multi-stage variable gain amplifier (VGA) and a low-pass filter (LPF). The 5-stage VGA is composed of two variable gain units followed by three fixed gain units with DC offset cancellation (DCOC). The first variable gain unit with a self-compensated transistor pair and compact active inductor load is designed for dB-linear functionality and bandwidth extension, respectively. Moreover, a proposed error compensation method is applied to the second cascaded variable gain unit for further dB-linear gain error correction. A 4th-order Butterworth transconductance-capacitance (Gm-C) LPF with flipped source follower (FSF) as an input transconductance stage for linearity enhancement is designed after the VGA stage. The prototype chip is implemented, and measurement results show a dB-linear gain range from −18 to 26 dB with less than 0.5 dB-linear gain error with a bandwidth of 4 GHz. The VGA and LPF consume 8.3 mW and 3 mW, respectively, under a 1 V power supply, while the entire ABB occupies an area of 0.94 mm² with an active core area of only 0.045 mm².

This letter presents an ultralow-power (ULP) 2.4-GHz envelope detector (ED)-first wake-up receiver (WuRx) for wireless body area network (WBAN) applications. A passive ED with the stepped capacitor technique is proposed to achieve a 23% reduction in rise time enhancing the data rate compared to traditional Dickson ED. Furthermore, a current-reused baseband amplifier (BBA) with the self-cascode technique is presented to achieve a 4.4-dB gain enhancement while saving 47% power consumption compared to traditional ones. The prototype chip is fabricated in 40-nm LP CMOS process and the measurement results show that a sensitivity of −59 dBm with a 1-kb/s on−off keying (OOK) data rate is achieved with a total power consumption of only 2.4 nW under a 0.4-V power supply.