Ultrahigh-sensitivity multi-parameter tacrolimus solution detection based on an anchor planar millifluidic microwave biosensor.

To detect drug concentration in tacrolimus solution, an anchor planar millifluidic microwave (APMM) biosensor is proposed. The millifluidic system integrated with the sensor enables accurate and efficient detection while eliminating interference caused by the fluidity of the tacrolimus sample. Different concentrations (10-500 ng mL-1) of the tacrolimus analyte were introduced into the millifluidic channel, where it completely interacts with the radio frequency patch electromagnetic field, thereby effectively and sensitively modifying the resonant frequency and amplitude of the transmission coefficient. Experimental results indicate that the sensor has an extremely low limit of detection (LoD) of 0.12 pg mL-1 and a frequency detection resolution (FDR) of 1.59 (MHz (ng mL-1)). The greater the FDR and the lower the LoD, the more the feasibility of a label-free biosensing method. Regression analysis revealed a strong linear correlation (R2 = 0.992) between the concentration of tacrolimus and the frequency difference of the two resonant peaks of APMM. In addition, the difference in the reflection coefficient between the two formants was measured and calculated, and a strong linear correlation (R2 = 0.998) was found between the difference and tacrolimus concentration. Five measurements were performed on each individual sample of tacrolimus to validate the biosensor's high repeatability. Consequently, the proposed biosensor is a potential candidate for the early detection of tacrolimus drug concentration levels in organ transplant recipients. This study presents a simple method for constructing microwave biosensors with high sensitivity and rapid response.

A high-performance wearable pressure sensor based on an MXene/PVP composite nanofiber membrane for health monitoring.

Flexible and wearable pressure sensors have attracted extensive attention in domains, such as electronic skin, medical monitoring and human-machine interaction. However, developing a pressure sensor with high sensitivity, mechanical stability and a wide detection range remains a huge challenge. In this work, a flexible capacitive pressure sensor, based on a Ti3C2T x (MXene)/polyvinyl pyrrolidone (PVP) composite nanofiber membrane (CNM), prepared via an efficient electrospinning process, is presented. The experimental results show that even a small mass fraction of MXene can effectively decrease the compression modulus of the PVP nanofiber membrane, thus enhancing the sensing performance. Specifically, the sensor based on (0.1 wt% MXene)/PVP CNM has a high sensitivity (0.5 kPa-1 at 0-1.5 kPa), a fast response/recovery time (45/45 ms), a wide pressure detection range (0-200 kPa), a low detection limit (∼9 Pa) and an excellent mechanical stability (8000 cycles). Due to its superior performance, the sensor can monitor subtle changes in human physiology and other signals, such as pulse, respiration, human joint motions and airflow. In addition, a 4 × 4 sensor array is fabricated that can accurately map the shape and position of objects with good resolution. The high-performance flexible pressure sensor, as developed in this work, shows good application prospects in advanced human-computer interface systems.

Microfluidic microwave biosensor based on biomimetic materials for the quantitative detection of glucose.

This paper presents a microwave microfluidic biosensor for monitoring blood glucose levels. The glucose sensor is a triple ring microstrip patch antenna integrated with a biomimetic microfluidic device capable of measuring a fixed volume of glucose solution. The sensor was utilized to detect 50-500 mg/dL glucose solutions. The interaction of the glucose solution with the electromagnetic field on the patch's surface influences both the resonance frequency and the magnitude of reflection coefficient. The results indicate that the microfluidic device can reduce experimental error and enhance the correlation between glucose concentration, resonant frequency, and reflection coefficient. Finally, the microfluidic sensor had a sensitivity of 0.25 MHz/(mg/dL), a detection limit as low as 7.7 mg/dL, and correlation coefficients of resonance frequency and reflection coefficient with a glucose concentration of 0.996 and 0.984, respectively. The experiment on the sensor's stability verifies the sensor's excellent stability and rapid response (~ 150 ms). Consequently, the device can be used to differentiate the concentration of glucose solutions, as well as to detect blood glucose levels at an early stage.

Correction: Nanoarchitectonics of p-type BiSbTe with improved figure of merit via introducing PbTe nanoparticles.

[This corrects the article DOI: 10.1039/D1RA07138F.].

Nanoarchitectonics of p-type BiSbTe with improved figure of merit via introducing PbTe nanoparticles.

Bi0.4Sb1.6Te3 (BST) is known to be a unique p-type commercial thermoelectric (TE) alloy used at room temperatures, but its figure of merit (ZT) is relatively low for wide industrial applications. To improve its ZT value is vitally important. Here, we show that the incorporation of 0.5 wt% PbTe nanoparticles into BST concurrently causes a large enhancement of power factor (PF) and a significant reduction of lattice thermal conductivity κ L. The increase in PF mainly benefits from the optimization of carrier concentration, maintenance of high carrier mobility and constant rise in Seebeck coefficient. The decrease in κ L can be attributed to the enhanced phonon scattering by the dispersed PbTe nanoparticles and the interfaces between PbTe and the BST matrix by using the Callaway model. Specifically, an ultralow κ L of 0.26 W m-1 K-1 at 429 K is achieved for the composites incorporating 0.5 wt% PbTe nanoinclusions. Consequently, an excellent ZT = 1.6 at 482 K and a high average ZT ave = 1.38 at 300-500 K are achieved, indicating that incorporation of PbTe in BST is an effective approach to improve its thermoelectric performance.