This Letter presents a high accuracy silicon-on-insulator (SOI) capacitive accelerometer using a backside dry release process. To increase the yield rate of the process, the deep reactive iron etching (DRIE) process was improved using a grooved accompany wafer to balance the pressure inside the back cavity of the SOI devices. By using this method, almost all the devices after the DRIE will not crack. Thus, the yield rate is significantly increased. Furthermore, the DRIE process was improved by dividing the DRIE process into four stages to decrease the tilt angle of DRIE. It is experimentally demonstrated that the tilt angle of the side wall was decreased from 0.81° to 0.27° and the loss of the capacitive sensitivity caused by the error was decreased from 28 to 8%. Test results show that sensitivity, bias stability, and noise floor of the accelerometer is 3.1 V/g, 16 μg, and 3.1 μg/√Hz, respectively.

A microfield-effect transistor pressure sensor has been fabricated using conventional complementary metal–oxide–semiconductor process and microelectromechanical systems technology. The sensor platform consisted of a field-effect transistor (FET) device, electrode and Si diaphragm. Six lithography masks were prepared to develop the sensor fabrication process for arsenic ion implantation and diffusion, gate insulation layer (SiO₂), gate metal, metal interconnection, passivation layer and bulk micromachining patterns. Pt/Ti thin films as the gate metal, interconnection and electrodes were deposited by DC/radio frequency magnetron sputtering, and patterned and etched using the reactive-ion etching process. The channel length and width between the source and the drain were approximately 10 and 5500 μm (W:L ratio = 550:1), respectively. The pressure sensor produced a change in current when pressure was applied to the sensing element and the electrical circuit was used to convert the current variation of the pressure sensor to a voltage output. The sensor response was measured using a voltage follower circuit to determine the change in drain current. The fabricated FET pressure sensor showed an almost perfect linear response for the applied pressure in the range 0–1200 kPa. The experimental results have shown that the pressure sensor had a sensitivity of 0.0096 μA/kPa.

In this reported work, the anisotropic etching properties of single-crystal silicon with tetramethylammonium hydroxide (TMAH) solution are examined in detail. The variations in the Si etching rate and surface morphology at different etching temperatures and TMAH concentrations are evaluated. The effect of isopropyl alcohol (IPA) additive is also examined. As the TMAH concentration (10–25 wt%) decreased, the etching rate increased from 10 to 70 μm/h at temperatures between 70 and 90°C. On the other hand, the etched surface roughness became degraded as the hillock density and corner undercut ratio increased. The additive of IPA affected the morphology of the etched surface to be flat. In addition, the IPA additive improved the etched surface significantly by decreasing the hillock density on the surface.

An optical micro-electro-mechanical-system pressure sensor based on light intensity modulation is described. The idea is to use light for signal transmission to replace electrical signal, which isolates the sensor from electrical signals, so that it is quite suitable in flammable and combustible areas such as petrochemical and oil well. The sensor is composed of silicon diaphragm and optical system. The silicon diaphragm is fabricated from bulk micromachining technology and Si₃N₄ film is deposited on diaphragm for reflecting light. In the optical cable, one fibre conducts source light to the diaphragm and the other fibres conduct the reflected light back to photoelectric detection circuit. When pressure is applied on the sensor, the diaphragm will deform causing the intensity shift of reflected light. Photoelectric detection circuit converts the intensity of reflected light to voltage. The voltage is proportional to reflected light intensity and, in turn, to the deformation of silicon diaphragm, so that pressure can be measured. Deformation of silicon diaphragm is acquired by finite element method. Sensor's optical features are also analysed. Sensor prototype has been fabricated and encapsulated. The measurement range is 0–20 MPa and experimental sensitivity is −7.2 mV/MPa.

A high temperature silicon on insulator pressure sensor utilising a Ti/TiN/Pt/Au electrode is presented for improving the thermal stability of ohmic contacts, which can work stably at high temperatures of up to 500°C. To analyse the characteristics of the electrode at high temperatures, a special test structure is measured using the linear transmission line method and Auger electron spectroscopy. To solve the measurement problem, a novel calibration setup is designed to calibrate the absolute pressure sensor at extremely high temperatures. The measurement results have shown that the pressure sensor has a nonlinearity error of 0.17%FS and a sensitivity of 0.24 mV/kPa with a measurement range of 30–150 kPa at 500°C, indicating the good thermal stability of the ohmic contacts.

Separation is one of the important pretreatment processes during detection in lab-on-a-chip. In this reported work, polydimethylsiloxane (PDMS) on a glass microchip with a combination of the spiral channel and backward facing step structure was designed to optimise the separation of suspended particles without any extra active powers of the electric or magnetic field. The spiral microfluidic chip was fabricated first by the foil-assisted CO₂ laser ablated polymethylmethacrylate (PMMA) master mould, followed by repetitive PDMS moulding and then bonded to a glass substrate. The CO₂ laser ablation of PMMA in air normally generated poor surface quality comprising bulges and scorches. The metal-foil-assisted laser ablation can effectively improve the above defects with conducting cover protection. The average height of the bulges was reduced from 5.0 to 1.5 μm and the channel width was reduced from 230 to 120 μm. The finished separation chips were operated at various syringe-controlled flow rates of 5–20 µL/min to test the performance. A high separation efficiency of about 99% could be achieved within a certain flow range of less than 15 µL/min under the simple structure with low-cost and time-saving.

Gecko and many insects have nanoscale fibrillary structures on their feet serving as adhesive devices. In recent years, van der Waals interaction has been proven to be the primary molecular origin for this kind of phenomena. However, the peeling zone and the cohesive zone both play significant roles in the peeling process while the peeling zone can be described by van der Waals force and the cohesive zone is dependent of molecular interaction. In this reported work, the case of peeling of two elastic bodies, in which the pull-off force depends linearly on the cohesive stress and is independent of the work of adhesion is considered. The adhesion interaction and peeling condition between a single biomimetic adhesive structure and a substrate is simulated as an axisymmetric geometries model, by encoding van der Waals force and molecular interaction in COMSOL software. The simulation takes theoretical fundamental equations as inputs, and by varying relative peel angles, functional variables are built to estimate peeling processes of the biomimetic adhesive structure in various conditions. The results show that the maximum pull-off force of the structure with different materials and pull-off force is decreasing in the peeling process but the cohesive force immediately raises while the contact area becomes smaller. Stress concentration occurs both on the top and at the base of the structure during the peeling process. The simulation results demonstrate that an optimal shape of the adhesive structure can be achieved by examining the simulated pull-off forces. To avoid failure occurring during the peeling process, the structure with a large base can decrease the stress concentrate at the bottom. Based on the analysis, the adhesive structure with an optimised half-hourglass shape is proposed.

Different capillary-driven planar baffle micromixers with a trigger valve which were fabricated on polymethylmethacrylate sheets using CO₂ laser ablation and thermal bonding are investigated. Two main modified staggered and meander baffle structures were used to compare the mixing efficiency. The modified staggered baffle structure has lower capillary flow resistance and faster speed compared with the meander one. Conversely, the meander baffle structure has higher mixing efficiency at lower flow speed with enough diffusion time than the modified staggered one. The effective channel height of the trigger valve was simulated to be between 220 and 434 μm for merging two fluids at negative capillary pressure. The experiments also verified the trigger value worked at the channel height of 351 μm for two fluids merged together to flow forward but it failed at 169 μm height for only one fluid flow without merging. The mixer with the meander baffle structure performed wiht the best mixing efficiency of 94% among the design structures because of the long flow time and short average diffusion length in the mixing zone.

DNA origami is one of the most promising ways to create novel two-dimensional (2D) and 3D structures, assemble inorganic and organic materials, and synthesise functional micro/nano systems. In particular, DNA origami structures consisting of nanotube configurations can function as mechanical components for encapsulating materials such as gold particles or drug proteins, due to their tubular structure, relatively high rigidity, high aspect ratio and other desirable characteristics, but certain mechanical properties such as radial rigidity have yet to be fully determined experimentally. A report is presented on the direct measurement of the radial modulus of a DNA nanotube structure by force–distance curve-based atomic force microscopy, in a magnesium ion solution. A Hertz model, corrected using the finite-element method to achieve greater realism, was employed to determine the DNA nanotube's actual radial modulus in two states, corresponding to the rigidity of a porous and electrostatically repulsive nanotube lattice, and the rigidity of a packed and elastic honeycomb lattice. Furthermore, the biphasic radial modulus was verified by estimation of the inter-helix electrostatic force and torsional rigidity of a six-helix DNA nanotube, with results comparable to those reported elsewhere. The anisotropy of the DNA nanotube honeycomb lattice revealed by the authors’ radial measurements should be useful when developing new DNA structures and may enable further applications that utilise DNA origami structures as a mechanical component.

Since high precision of working fluid charging is key to the evaluation of thermal performance, a novel perfusion method of a micro heat pipe (MHP) is presented. The MHP has a length of 26 mm, width of 20 mm and a thickness of ∼2.2 mm. The predetermined quantity of perfusion is 25 or 35 μl. Small volume and large capillary force render conventional vacuum perfusion methods quite impractical. To realise microscale and high precision of perfusion, the method of combining vacuum perfusion using a peristaltic pump and weight comparison before and after working fluid charging was used. The charging deviation of the method was <2 μl. After perfusion and sealing, the thermal performance testing of a MHP, which is engineered in light-emitting diode (LED) heat dissipation, was conducted and the input power varied from 1 to 7 W. The results show that high-power LEDs can reach the status of heat balance and can work steadily, and the maximum deviations of actual and simulated temperatures are 4.5 and 5.1°C, respectively, and the relative errors are 6.1 and 7.3%. Therefore, this perfusion method can be used for the working fluid perfusion of the MHP and makes it feasible for use in packaging manufacture of heat pipes.

Currently, the advancement of silicon transistor technology is being hindered by different issues such as scaling limits. It has become imperative to replace existing silicon technology with new technology to continue the scaling of MOSFETs. Thus, new materials and new production techniques are being studied laboriously to continue the trend set by Moore's Law. The graphene nanoribbon (GNR) and the carbon nanotube (CNT) are two such promising materials that can replace silicon in future MOSFETs. A study has been conducted of the effect of the relative dielectric constant on the device performances of a ballistic Schottky barrier GNR field-effect transistor (GNRFET) and a CNT field-effect transistor (CNTFET) for two different channel lengths and a comparative analysis between the two transistors is provided. When a gate material with a high relative dielectric constant is used in FETs, it has been observed that both the transistors show higher on-state drain currents for the different channel lengths. Moreover, the on and off-state current ratios and transconductance for the GNRFET and the CNTFET are calculated and plotted for further differentiation between the performances of the GNRFET and the CNTFET.

A solar cell texturing process using a two-step process that includes wet etching and dry etching has been developed. The surface reflectance and fill factor (FF) of the pyramid structure by general wet etching texturing process were 5.834 and 70.597%, respectively; the surface reflectance and FF of the two-step pyramid structure by wet etching and dry etching texturing process were 3.69 and 65.013%; and the surface reflectance and FF of the two-step pyramid structure by rounded pyramid and dry etching texturing process were 4.533 and 70.727%. The process of the two-step pyramid structure is as follows. First, the pyramid structure formed by the wet etching process was etched again with tetramethylammonium hydroxide solution. Then, the crest and the trough of the pyramid structure was fine etched, and rounded pyramid structures with a uniform n+ layer was formed. Secondly, a pyramid structure with a high angle on the rounded pyramid structure was formed by using reactive-ion etching with a metal mesh. The two-step pyramid structure by the wet etching and dry etching texturing process has a lower surface reflectance and higher FF than the pyramid structure formed of the wet etching texturing process. Therefore, the etching process is suitable for producing high-efficiency solar cells.

The charge character in the double-barrier quantum dots (QDs) in a well hybrid structure is investigated experimentally and numerically. The capacitance hysteresis phenomenon of a double-barrier InAs QDs and InGaAs quantum well hybrid structure is reported, as well as the carrier transport properties in the photoelectric device. Due to the coupling effect among multiple QDs, the photoelectric device's measured I–V and C–V curves show that the capacitance changes with the light intensity. When the dumping readout designed, it can enhance the sensitivity of the device at weak light illumination. This indicates that the photoelectric device has the potential to be a promising candidate both in quantum information applications and highly sensitive imaging applications.

This Letter proposes jagged discharge electrode with low discharge voltage, which is fabricated by the MEMS fabrication technique. The voltage multiplier, as energy accumulation module, was analysed and modified. Finite-element analysis has been done for simulating the arc generation. The discharge form of this device was investigated through the damage on the two electrodes by microscopic images. An encapsulated liquid-based triboelectric generator was utilised to charge high voltage for self-powering the system. This novel discharge system is promising for applications in sterilisation, ozone production and arc lightening.

Since the proposing of capacitive micromachined ultrasonic transducer by Khuri Yakub group in 1994 that this kind of transducer occupying the advantages of wide bandwidth, impedance matching well with the propagation medium especially in fluid and air and high sensitivity, has shown a great potential for wide ranges of applications. This Letter reports kind of micro-electro-mechanical systems (MEMS) capacitive ultrasonic transducer with the novel cavities embedded in the device layer of silicon on insulator wafer bonded with a glass substrate. The optimum geometric dimensions are confirmed by both mechanical vibrating of the membrane and the electrical characteristics analysis. Finite-element analysis is adopted to determine the operation mode. The safety and reliability of the proposed device is ensured by the obtained deflections and equivalent stress under operation/collapse voltage. The bottom electrodes of the proposed transducer are fabricated on the top surface of the glass substrate. The parallel parasitic capacitance is reduced, thus improving the electromechanical coupling coefficient. The test results show that the electromechanical coupling coefficient is 69.65%, which demonstrates that this proposed MEMS capacitive ultrasonic transducer structure can enhance the performance significantly.

The integration of thermal bimorph actuators and buckled cantilever structures to form an out-of-plane plate with adjustable angular positions is reported. This structure could be used as a platform to build other transducers such as optical micromirrors, scanning antennas, switches or low-frequency oscillators. The electromechanical characterisation has shown that these structures can adjust their angular position by 6° when they are operated using a DC source. The thermal characterisation performed by an infrared camera showed that the heat-affected zone reaches a maximum temperature of 125°C while the rest of the structure remains unaffected by the generated heat.

Dielectrophoresis-based separation of microparticles and living cells are studied with computational and experimental methods. The flow behaviours of particles are modelled and simulated using COMSOL Multiphysics 4.3a software (COMSOL Ltd). Lab-on-a-chip devices having a titanium (Ti) interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to investigate the most effective design for separating particles based on their sizes. Polystyrene particles in different diameters (3.2 and 9.8 µm) are used in the experiments. Green polystyrene particles from red ones are fully separated in a current design. Enrichment of Jurkat cells having 10.1 average diameter in phosphate buffer solution (PBS) medium is achieved.

Cuprous oxide (Cu₂O) films have been synthesised by a convenient and green soft chemical route at room temperature. The films were obtained through the chemical reduction of copper acetate by ascorbic acid in solutions with ethylene glycol and deionised water. X-ray diffraction, energy-dispersive X-ray spectrometry, scanning electron microscopy (SEM), atomic force microscopy, as well as UV–Vis spectroscopy (UV-Vis) were used to characterise the resulting films. It was obvious from the SEM image that the obtained films were composed of nanosphere particles with a size of 100–400 nm. The photocatalytic activity of degradation of methyl orange (MO) of the obtained Cu₂O films, H₂O₂ and H₂O₂/Cu₂O films system under visible light irradiation was also investigated. The results have shown that the system exhibits high catalytic ability under visible light irradiation. Also, there was a strong synergistic effect between the obtained Cu₂O films and H₂O₂ when the system was used to degrade MO.

A graphene nanoribbon parallel-plate waveguide (GNPPW) in the infrared band is reported. Owing to the large loss, difficulty of control and shortages of traditional metals, graphene has been considered as a novel plasmonic material as the substitute for metals. In this reported work, the relationship between the dispersion characteristics, the propagation loss of the GNPPW's surface plasmon and the filled dielectric into the GNPPW are analysed. The results show that filling dielectric with a large permittivity can improve the confinement of the symmetric mode supported by the GNPPW. Moreover, the transmission distance and dispersion characteristics of the GNPPW under different chemical potentials are analysed. The performance of the waveguide can be effectively controlled by the filling dielectric and external means such as static voltage, achieving easy regulation and control of graphene. This research has some reference values for the production of novel graphene waveguide devices.

Multi-walled carbon nanotubes decorated with Fe₃O₄ nanoparticles (Fe₃O₄NPs/MWCNTs) were prepared and used to fabricate an electrochemical sensor for the determination of enrofloxacin. The electrochemical response of the carbon paste electrode (CPE) modified with Fe₃O₄NPs/MWCNTs towards enrofloxacin was investigated by cyclic voltammetry and differential pulse voltammetry. The results indicated a remarkable growth in the oxidation peak current together with negative shift in the oxidation peak potential for enrofloxacin, in comparison to both the unmodified CPE and the CPE modified with MWCNTs (MWCNT/CPE). The prepared sensor displayed a rapid and sensitive response towards enrofloxacin, which was attributed to the synergetic electrocatalytic effect of Fe₃O₄NPs and MWCNTs. The sensitivity enhancement with nearly three orders of magnitude (0.3–100 μM) was gained, compared with the MWCNT/CPE, with a detection limit of 0.09 µM (S/N = 3). The proposed method was successfully applied for the highly sensitive determination of trace amounts of enrofloxacin in cow's milk, egg, honey and chicken samples.

A report is presented on the facile fabrication of Ni(SO₄)_0.3(OH)_1.4 nanowires via the hydrothermal synthesis method. The outcome demonstrates that the existence of SO₄ ²⁻ and a comparatively lower pH are of great essence to form nanowires morphology rather than flake-like or amorphous ones. When the molar ratio of SO₄ ²⁻ to OH⁻ was 1:1, almost pure nanowires of diameter 20−30 nm and several micrometres long could be obtained. Ni(SO₄)_0.3(OH)_1.4 is actually a type of α-Ni(OH)₂. The growth mechanism of this hydroxyl-lacking hydroxide is discussed. The embedded SO₄ ²⁻ between Ni(OH)₂ layers can realise electrostatic equilibrium which may ensure an hcp crystal structure of Ni(OH)₂ having the trend to grow along the (001) direction. On the contrary, when SO₄ ²⁻ was superseded by other anions, the nanowires would progressively convert to nanosheets, accompanied by an α-phase to β-phase transformation.

A high photoexcited carrier multiplication photodetector operating at room temperature is reported. The device is a GaAs n-i-n photodetector with double-barrier AlAs in which a thin quantum well contains a mixture of quantum dot (QD) structures. This special structure makes the proposed photoelectric detector have high sensitivity to light under an operating temperature of 300 k. Its current responsivity can reach about 7 × 10¹¹ A/W with 0.01 picowatts 633 nm light power and −0.5 V bias. The response voltage is 7 mV at an integration time of 80 μs. The voltage responsivity reached about 2.7 × 10⁹ V/W. An embedded micro-spectrometer based on the high-sensitivity features of the photodetector has also been designed. By means of QD fluorescent sample testing and comparison, the proposed spectrometer is found to have higher sensitivity and a shorter integration time than the ‘NOVA’ spectrometer (product model of the spectrometer of ideaoptics, China) based on a backside-illuminated CCD (Hamamatsu, S7031–1006S). The QD spectrometer was mounded in a hyperspectral microscopy imaging system with an optical path switcher. The system has been used to analyse and to make a comparative study of the biological section. This kind of spectrometer with highly sensitive linear QD detectors has good application prospects in the fields of biological science, medical diagnosis and environmental detection.

The reaction of CaO with SO₂ is one of the most important methods for flue gas desulphurisation. Two methods for producing high-capacity sorbents are investigated: a nanoporous CaO and a modified sorbent by washing with acetic acid. The capturing capacities of these sorbents are compared with CaO derived from natural limestone calcination. The solid conversion at 850°C after 3 h for the natural sorbent was only 5%, while this value was improved by up to 13 and 46% for acid-washed and nanosynthesised sorbents, respectively. The effect of various sorbent pore size distributions on SO₂ capture capacity is investigated.

Theoretical and experimental investigations are conducted into the thermal effect on resonance conditions of microfibre double-knot resonators. A double-knot microfibre resonator which utilises heat for optical path correction is introduced to increase the finesse. The proposed resonator consists of two knots with radii of 357.66 and 357.73 µm which are placed in series. Each individual knot has a finesse of 5 and an extinction ratio of 6 dB. When placed in series, the extinction ratio of the comb spectrum varies from 3.5 to 15 dB by controlling the resonance wavelength of both knots through optical correction. Optical path correction is implemented by placing a hot metal bar with a temperature of 30°C close to the smallest knot. This path resulted in a flat comb spectrum with a high extinction ration of 15 dB. The produced resonance has an unchanged free spectral range of 715 pm, a quality factor of 20 000, FWHD of 85 pm and a finesse of 9.5.

The nonlinear dynamics of a bistable micro/nano-electro-mechanical system resonator composed of an arch-shaped microbeam is investigated. The initially curved microbeam is actuated through a combined DC and AC electrostatic parallel plate field. A single degree of freedom model obtained using the Galerkin's decomposition method with distributed electrostatic force is implemented in order to investigate the resonator dynamics near its primary resonance. According to the shape of the potential energy function which depends on the system parameters, the nonlinear dynamics of the system are classified into certain categories. The appearance of various nonlinear phenomena including dynamic snap-through, dynamic pull-in, chaotic or large amplitude vibrations, hysteresis and softening-type behaviours are discussed within the introduced categories. A typical case scrutinised on detail, showing consequent snap-through instabilities which are responsible for transitions between the present stable configurations of the arch-shaped microbeam. Details of the resulting hysteresis loop governing these transitions are discussed. Moreover, discussion is provided about the formation of the hysteresis loops which can affect the filtering functionality of the proposed bistable MEMS resonator.

A facile and fast approach is demonstrated for the production of well-dispersed molybdenum disulphide (MoS₂) nanosheets through the exfoliation of MoS₂ bulk using a high-pressure homogeniser in pure solvents. The MoS₂ bulk was infiltrated in dimethylformamide for several hours, then homogenised at 100 MPa for 10 min, followed by centrifugation to obtain few-layer MoS₂ nanosheets. The structure and morphology of the nanosheets were examined by atomic force microscopy, X-ray diffraction and transmission electron microscopy. The bulk also had an exfoliation in water and alcohol, but the suspension was unstable. It can be concluded that the energy as well as solvents plays a critical role in the liquid–phase exfoliation. These results provide a physical perspective for understanding the exfoliation of other layered materials in aqueous and ethanol dispersions.

Na⁺montmorillonite (MMT) was modified with L-cystine, polyvinylpyrrolidone or mercaptoacetic acid and then silver (Ag) was loaded on the modified MMTs via ion-exchange reaction under microwave irradiation for 4 min, and finally the Ag ions were turned to Ag nanoparticles (Ag NPs) under the irradiation of an ultraviolet lamp. The Ag-loaded L-cystine-modified MMT (Ag@AA-MMT) with an Ag content of 10.93 wt% was the highest of all, suggesting the distinct advantage of microwave-assisted ion-exchange reaction on a modified MMT. X-ray photoelectron spectroscopy confirmed the successful loading of silver and the strong interaction between sulphur and Ag. Scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy and X-ray diffraction patterns proved the existence and formation mechanism of metallic Ag NPs. The Ag-loaded modified MMT has shown a slow release property and good thermal stability owing to the shielding effect of the MMT layers. The Ag@AA-MMT, showing a very excellent antibacterial property and catalytic activity, exhibited a wide range of potential applications.

An integrated microoxygen sensor based on the nanostructured TiO₂ thin film is presented. A pair of interdigitated electrodes was designed with the microheater around them on the same layer, which was aimed at simplifying the structure and avoiding fracture of the embedded heater. To fabricate the sensor chips, an optimisation process consisting of 14 steps was designed. The adiabatic cavity was formed by releasing the Si substrate from backside to a certain thickness at first, then a TiO₂ film was prepared by the sol–gel process and patterned by the wet etching process, after that electrodes and the heater were patterned and finally the remaining silicon was thinned further. Response properties to different gases were tested, and the sensor shows a good sensitivity of 0.093 and high selectivity of 0.258 to O₂ than H₂, response time of 51 s and hysteresis of 2.93%. The integrated microoxygen sensor has potential applications on the occasions of miniaturised, integrated, low power and mass production.

Highly mono-disperse carbon spheres (CSs) with a tunable diameter of 300–4000 nm are shown to be successfully synthesised using sugar-rich wastewater as carbon sources and polyacrylamide (PAM) as a size-controlling agent. The effects of PAM and pH on the morphology and size were also investigated. Experimental results showed that PAM acted as a size-directing agent which directs the self-assembly of sugar from wastewater to form the spheroidal particles. The size of CSs could be increased from 300 to 600 nm without any alteration in the morphologies by altering the solution pH from 7 to 12. Furthermore, the size of spheroidal carbon particles can be easily controlled by increasing the concentration of PAM from 0.05 to 0.1% (w/v) at pH 12. The largest sizes of CSs grew nearly 4000 nm without damage to their morphology or broadening of their size distribution with the addition of 0.1% PAM. On the basis of the experimental results, a mechanism is proposed to elucidate the formation of CSs with a wide diameter range. It is believed that this work not only provides a novel potential way to utilise wastewater, but also puts forward a facile sustainable approach to synthesise size-controllable CSs.