Modular droplet actuator drive

A droplet actuator drive including a detection apparatus for sensing a property of a droplet on a droplet actuator; circuitry for controlling the detection apparatus electronically coupled to the detection apparatus; a droplet actuator cartridge connector arranged so that when a droplet actuator cartridge electronically is coupled thereto: the droplet actuator cartridge is aligned with the detection apparatus; and the detection apparatus can sense the property of the droplet on a droplet actuator; circuitry for controlling a droplet actuator coupled to the droplet actuator connector; and the droplet actuator circuitry may be coupled to a processor

Developing and optimizing microfluidics platform for fabricating lignin nanoparticles.

Introduction: Lignin is a complex organic polymer, produced in large quantities as a by-product from pulp and paper industries. Despite of large-scale production, lignin is not being utilized for high value applications. Recently, researchers are showing greater interest in fabricating lignin-based nanoparticles for drug delivery and other application. However, it is challenging to fabricate lignin nanoparticles due to its complex chemical structure. Microfluidics technology used for nanoparticle synthesis because it works on microscale dimension with rapid and tunable mixing for better control over nanoprecipitation by controlling different parameters like flow rate, precursor and mixing time. The objective of this study is to develop method to fabricate lignin nanoparticles using microfluidics platform. Material and methods: Two type of microfluidics chips were used for sequential precipitation, one consisting of two tapered ends and another with one tapered end. Kraft lignin (0.1%) was dissolved in ethylene glycol and lignin was precipitated with acetone and NaOH (0.1M). The fabricated nanoparticles were characterised by dynamic light scattering (DLS) and transmission electron microscope (TEM). Result and Discussion: Two tapered end microfluidics chip were used to precipitate lignin because two solvent, acetone as counter solvent and NaOH as triggering precipitation was utilized, resulting nanoparticles of hydrodynamic particle size 162.5±1.82 nm, PDI 0.12±0.02 and zeta potential -24.6±2.17 mV at FRR 2:20:1 ml/hr (lignin:2ml/hr, acetone:20ml/hr, and NaOH:1ml/hr) were obtained. Whereas hybrid lignin nanoparticles (Ultra-small nanoparticles trapped in the lignin matrix) with hydrodynamic particle size of 129.73±5.91 nm, PDI 0.19±0.003 and zeta potential -15.5 mV were fabricated by sequentially precipitating kraft lignin with dual microfluidics chips setup (two tapered end and one tapered end chip). The solution from two tapered end chip was directly transferred at the rate of 23 ml/hr to the inner inlet of one tapered end chip, and precipitated at the FRR 3:20 ml/hr (3ml/hr:NaOH 0.1M) and 20ml/hr:acetone) as respective solution were infused in the outer most channel of one tapered end chip. Particles characterized with TEM showed hybrid nanoparticles consist of Ultra small primary particles were embedded in lignin matrix. Conclusion: TEM image analysis suggest that we successfully developed method to fabricate hybrid lignin nanoparticles with the average size range from 20-50 nm utilizing microfluidics platform. Morphological analysis by TEM shows that nanoparticles are composed of ultra-small primary nanoparticles of 2-4 nm were trapped in matrix of different material. Further chemical characterization of this nanoparticles will help to understand its application

High Efficiency Polymer based Direct Multi-jet Impingement Cooling Solution for High Power Devices

Liquid jet impingement cooling is an efficient cooling technique where the liquid coolant is directly ejected from nozzles on the chip backside resulting in a high cooling efficiency due to the absence of the TIM and the lateral temperature gradient. In literature, several Si-fabrication based impingement coolers with nozzle diameters of a few distributed returns or combination of micro-channels and impingement nozzles. The drawback of this Si processing of the cooler is the high fabrication cost. Other fabrication methods for nozzle diameters for ceramic and metal. Low cost fabrication methods, including injection molding and 3D printing have been introduced for much larger nozzle diameters (mm range) with larger cooler dimensions. These dimensions and processes are however not compatible with the chip packaging process flow. This PhD focuses on the modeling, design, fabrication and characterization of a micro-scale liquid impingement cooler using advanced, yet cost efficient, fabrication techniques. The main objectives are: (a) development of a modeling methodology to optimize the cooler geometry; (b) exploring low cost fabrication methods for the package level impingement jet cooler; (c) experimental thermal and hydraulic characterization and analysis of the fabricated coolers; (d) applying the direct impingement jet cooling solutions to different applications

Liquid metal based convective cooling systems

Forced convection is one of the major mechanisms used for cooling of electronic systems. However, the problems associated with the size, fabrication, integration and maintenance of conventional convective cooling systems has limited utility of such technologies for thermal management of miniaturised electronic components. The existence of fluidic interfaces between the pump and the hot spot not only increases the footprint of the cooling system but also may cause additional problems such as the leakage of the coolant medium as well as reducing the response time of the pump. A new class of convective cooling systems, which can address these limitations can facilitate the generation of highly integrated electronic systems. Gallium based liquid metal alloys have been recently used for making soft electronic and microfluidic devices. These alloys, which inherit the properties of both liquid and metal, have been utilised for making a new class of soft microfluidic elements such as pumps, mixers, valves, heaters and electrodes. These advances have motivated me to develop a novel class of liquid metal based convective cooling systems, which can be used for temperature regulation of both flow-through and flow-free systems in both static and dynamic modes. As my first contribution, I demonstrated the utility of liquid metal pumps for the localised cooling of hot spots. These pumps, which consist of millimetre size liquid metal droplets, can be easily installed at desired locations of the system. Applying a low voltage square wave signal creates sufficient surface tension gradient across the droplet, providing a continuous flow of coolant medium through the cooling channel. The flow rate can be readily modulated by varying the frequency of the signal. Furthermore, the high thermal conductivity of liquid metal droplet allows it to serve as a heat sink, enhancing the dissipation of heat into the cooling channel. This hybrid pump-heat sink can reduce the temperature of localised hot spots, and has been characterised in various operating conditions. As my second contribution, I demonstrated the unique features of liquid metal pumps for the transient cooling of hot spots. The elimination of mechanical moving elements and interconnecting tubes significantly reduces the response time of these pumps, enabling them to reduce the temperature of hot spots in a few seconds. As my third contribution, I investigated the capability of liquid metal pumps for producing customised temperature profiles inside an isolated flow-free liquid chamber. A pair of liquid metal pumps is located along the opposite sides of the chamber to induce vortices inside the liquid chamber. The configuration and rotational velocity of the vortices can be easily modulated by varying the frequency of the signal. Customised temperature gradients can be produced inside the liquid chamber, breaking the inherent limitations of diffusive heat transfer in isolated chambers. As my fourth contribution, I studied the ability of liquid metal pumps for creating controllable spatiotemporal temperature gradients inside an isolated liquid chamber. The rapid reconfiguration of vortices and the dominance of convective heat transfer enable the rapid change of temperature profile inside the chamber. The versatility of liquid metal based convective cooling systems facilitates their incorporation into miniaturised yet highly integrated electronic devices. Accordingly, the simplicity and flexibility of such cooling systems enable their integration into the emerging soft and stretchable devices