Long‐term and highly sensitive electrophysiological signal detection is the primary issue for wearable health monitoring. The critical issues of pre‐gelled wet electrodes as conventional approaches are limited conductivity and low adhesivity owing to the dependence of moisture concentration. Along this line, this paper presents a biocompatible, mechanically robust, water degradable, and intrinsically conductive organic composite dry film electrode based on poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), hydroxyethyl cellulose, and dopamine. The effects on PEDOT:PSS structure transition are studied systematically according to the combination of each component with various analytical methods including morphological, chemical, electrical, and mechanical characterization. The proposed film exhibits high conductivity (292 S m–1) and robust mechano‐electrical stability (only 8% of resistance change under 110 of fully flat‐bended cycles) owing to the weak but synergetic interactions between the components. Furthermore, low noise, clear signal, and long‐term stability for a wireless electrocardiogram and electromyogram signal sensing is achieved using the proposed dry electrode.
Conductive Dry Electrode for Electrophysiological Signal Detection
In article number 2200594, Young‐Joon Kim, Hocheon Yoo, and co‐workers demonstrate that a biodegradable polymeric composite electrode allows long‐term and sensitive electrophysiological biosignal sensing. The robust mechano‐electrical properties of the dry organic film are achieved through the weak‐molecular interaction between the PEDOT:PSS, HEC, and dopamine. Consequently, the epidermal electrodes successively detect the ECG and EMG signals using a wireless measurement system.
A wafer‐level packaging (WLP) technology for millimeter‐wave power devices is presented, which features simple fabrication, low‐signal transition loss, and thermal consideration. Instead of using a rigid interposer, the proposed WLP technology incorporates thick copper sheet and an adhesive tape as the initial carrier. Short electroplated interconnection showed transition loss within 0.2 dB and return loss above 20 dB, at frequency range up to 30 GHz. We demonstrate the WLP with an RF power amplifier at 28 GHz. The power‐added efficiency (PAE) of the power amplifier packaged in the proposed technology is 30% at an output power of 27.5 dBm, which is identical to an unpackaged integrated circuit (IC) wire bonded on a printed circuit board. The size of the IC, and the final packaged sample was 2.2 × 1.5 × 0.1 mm3 and 3.3 × 2.4 × 0.2 mm3, respectively.
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