Professor in MEMS (microelectromechanical systems)

Professional biography:

Prof. Jack Luo joined the University of Bolton in January 2007 as a professor. His current research interests include nanomaterials and nanodevices, physical and biochemical sensors, microactuators, microfluidics and lab-on-a-chip, flexible electronics and energy harvesting technologies.

Jack Luo received his PhD degree from the University of Hokkaido, Eng. Faculty, Japan in 1989 on "Preparation and Electrical Characterization of InGaAs and InP Field Effect Transistor Structures". He worked as a process engineer (1990) at Hoxan Co. Sapporo, Japan, to develop high efficiency crystalline silicon solar cells. He then be a research associate (1990) and senior research (1993) fellow at Cardiff University, U.K, working on III-V compound semiconductor devices. During 1995 and 2002, he worked in industry as an Engineer, Senior Engineer and Manager at Newport Wafer Fab. Ltd, Philips Semicond. Co. and Cavendish Kinetics Ltd, respectively, developing CMOS and MEMS products and processes, gained substantial experiences in R&D, project and team management. In 2002, he re-joined academe, and was a Senior Research Associate in Engineering Department, Cambridge University with responsibility for MEMS activities. 

Current research interests:

Biosensors, Microfluidics and Lab-on-chip

Lab-on-chip with integrated biosensors and microfluidics has received great attention owing to its potential in diagnosis of diseases, cancers and illnesses at early stage, enabling measures to be taken to cure or to prevent them. We have been developing biosensors, mostly based on acoustic wave, microfluidics technologies since 2005. We have developed surface acoustic wave (SAW) devices, and film bulk acoustic resonator (FBARs) based biosensors using piezoelectric (PE) thin film ZnO and AlN on silicon structures, and have demonstrated their suitability for detection of biomolecules and bioreaction such as bovine serum albumin (BSA), prostate antigens and antibody reaction and odorant biobinding reaction etc. By utilizing carbon nanotube network layer as the top electrodes, we have fabricated FBARs with Q-factor up to 2000 (Fig. 1) and a mass sensitivity near 10-15g, which is around the mass of a single virus.

Fig1
Fig.1. FBARs with CNTs as the top electrode (a), comparison of frequency responses for FBARs with metal and CNT top electrodes.

By utilizing SAW as the actuation force, we have realized many microfluidic functions such as streaming, pumping and mixing, nebulization (atomization), droplet generation etc for minor volume liquid (picolitres to tens of microlitres).

Fig2
Fig. 2. Regeneration of acoustic streaming pattern in a droplet by FEA modeling (a), streaming velocities measured on a ZnO/Si SAW device (b) and SAW-induced nebulization.

Flexible and transparent electronics

Flexible and transparent electronics are one of emerging technologies with broad innovative applications, particularly useful for wearable and implant electronics.  We have developed unique flexible and transparent SAW devices and various sensors with PE ZnO films deposited on polymer and flexible glass substrates (Fig. 3). We also fabricated FBARs on arbitrary substrates (demonstrated with Si, glass, copper and paper) by using a low acoustic impedance polymer as the acoustic isolation layer (Fig. 4), which enables the integration of FBARs on CMOS substrates. 

Fig3
Fig. 3. Schematic of a flexible SAW device (a), a photo and transmission spectra (b) of the fabricated flexible SAW devices with a ZnO film deposited on a polyimide substrate.

Fig4
Fig. 4. FBARs fabricated on a glass substrate (a), typical transmission characteristics (b) and a summary of Q-factors for FBARs on various substrates. 

By utilizing these acoustic wave devices, we have developed various flexible and transparent sensors, including temperature sensors, pressure sensors, ultra-broad range strain sensors and humidity sensors. Multi-variable sensors have been developed by utilizing multiple resonances, such as humidity-temperature, humidity-strain, strain-temperature sensors. We have also demonstrated that the flexible SAW can be utilized to perform all microfluidic functions such as streaming, pumping, particle concentration etc, thus allowing us to develop flexible lab-on-chip biodetection systems.

Fig5
Fig. 5. Typical frequency response of a graphene oxide on SAW humidity sensor (a), its stable performance over 60 days, and SAW on flexible Willow Glass strain sensors with more than five times broader strain ranges (c).

Polymer-based microactuators for biomedical applications 

We have developed various smart polymers and composites and their actuators for biomedical and healthcare applications.

  1. Shape memory polymers (SMP): We developed a process to synthesis transient temperature shape memory polymers and studied SMP-based pressure adjustable bandages for potential treatment for leg ulcers. By incorporating various nanoparticles such as CNTs, Al2O3 and carbon black etc, we have obtained SMP composites with high mechanical strength or electrical conductivity which allows us to develop SMP-actuators controlled electrically with potential for developing implantable medical devices. 
  2. Ionic polymer-metal composites (IPMC):  IPMC-based actuators are able to deliver much larger forces and displacements at very low voltage (<3V) in wet environment, particularly useful for the development of implantable medical devices. We have developed a process to fabricate IPMC and conducted feasibility study on IPMC based actuators, gained substantial knowledge of the material. Current interest is to develop IPMC or other electroactive polymer based artificial organs or medical devices.
  3. Electronics skin (E-skin) with multiple sensations: E-skin is a cutting-edge technology with broad applications in patient condition monitoring, healthcare or performance monitoring for sportsmen, artificial intelligence and robot developments etc. we have developed flexible E-skins with multiple sensations, including touch, pressure, temperature and multiple-pains with very high sensitivities. Current focus is to increase the ability for large strain and bendability etc, and to explore applications.  We also developed a method to reconstruct a 3D object in touch with the E-skin.

Fig7
Fig. 7. Photos of the fabricated E-skin, detection of touch by a finger and a foot of a model lizard, and a hot bolt by the E-skin

Nanomaterials and nanodevices

Nanomaterials possess a number of unique properties, and can be utilized to develop high performance smart composites/structures, new electronic devices. We have been developing various nanomaterials and utilized them for composites, coatings and electronic devices. The main activities include

  1. Resistive switching devices (Memristors): ZnO films grown by ALD and sputtering, chicken albumen and gelatine etc with thickness of tens of nanometres have been utilized to fabricate resistive switching devices, demonstrated their stable high performance for cyclic switching up to 104 times. Memristors with dissolvable metals as the electrodes  showed to dissolve in water within a few days, demonstrated their potential for applications as transient electronics in environment or in human body.    
  2. Hard coatings with nanomaterials: Nickel, chromium and copper coatings have been incorporated with nanoparticles to improve their mechanical and tribological performances for machineries and actuators. Nanomaterials used for these coatings include CNTs, graphene and derivatives, Al2O3, TiO2 etc. Significant improvement in Young’s modulus, hardness, wear and corrosion resistances by more than double have been obtained.
  3. Performance-enhancement for sensors: nanomaterials have significantly large surface area; use of nanomaterials could enhance sensor or electronics performance remarkably. We have used graphene oxide and silver nanoparticles to develop humidity sensors with sensitivities improved by orders of magnitudes, and CNTs for top electrode as well as sensitive layer for bio-reaction for FBAR biosensors etc.
  4. ZnO nanomaterial based electronic devices: ZnO nanostructures such as nanorods, nanoneedles and belts have been synthesized hydrothermal methods, and have been utilized as sensing layer for humidity, UV-light and hybrid piezoelectric/triboelectric power generators.

Energy harvesting devices and systems

We used piezoelectric fiber composite actuators to harvest vibration energy, and developed the corresponding circuit for voltage rectification and power storage. Currently we focus on energy harvesting using triboelectric (TE) and electrification effects as they can produce voltages and power outputs 2-3 orders of magnitudes higher than those of PE-based generators. Fig. 8 is a simple example of Al foil-PDMS/Al foil TEG (photo and typical voltage output under pressure). The maximum voltage produced is exceeded 300V. We have demonstrated biomaterials can be used to develop triboelectric generators with voltage outputs up to 250V obtained. Furthermore, PE and triboelectric hybrid structure shows better performance than single mechanism-based generators.

Fig8
Fig. 8. Photos and voltage output of an Al foil-PDMS/Al foil based TEG

We have synthesized PVDF films Exclusive self-aligned b-phase with abnormal piezoelectric coefficient up to -50 pm/V, nearly twice the ordinary values.

Fig9
Fig. 9. PVDF films synthesized by low temperature phase inversion process, its b-phase content (a), piezoelectric coefficient(b) and voltage produced of the PVDF membrane(c).

Current research focuses are to develop energy harvesting devices for wearable/implantable electronics and for wireless sensing application, and to develop high efficiency fuel cells by using carbon-based electrode materials such as graphene and its derivatives, CNTs embedded with noble metal nanoparticles. 

Teaching Responsibilities:

Module leader for:

  1. Renewable Energy Systems and Devices for Renewable Energy and Environment Technology MSc courses;
  2. Intelligent bioengineering System, for Medical and Healthcare Devices MSc Course.

Other course and lectures taught:

  1. MEMS  course (36 lectures);
  2. Microfluidics (2 hr) and non-organic coatings (2 hr) for Biomedical Devices module;
  3. Thin Film Technologies (4hr) for energy for Advanced materials for micro-energy systems module;
  4. MEMS and microchips fabrication (4 hr) for Advanced Materials,;
  5. Rapid prototyping & rapid tooling (4hr) for Advanced Materials;
  6. Digital circuits;
  7. Analogue electronics;
  8. Engineering drawing. 

Publications and Research Outputs

  • 14 international patents,
  • Over 170 papers published in peer reviewed journals,
  • ~160 papers presented at international conferences and workshops, about thirty of them were invited talks,
  • 7 book chapters,
  • Guest editor for six special issues on MEMS and nanomanufacturing,
  • Co-editor-in-Chief of International Journal Nanomanufacture (2009-2015),
  • Associate Editor of Chinese Journal Sensors & Actuators,
  • Editorial board member for a number of journals including Scientific Report.

Selected recent publications

  1. T.B. Xu, F. Gao, W.B. Wang, X.L. Bian, X.Z. Wang, W.I.Milne and J.K.Luo, High resolution skin-like sensor capable of sensing and visualizing various sensations and three dimensional shape, Sci. Rep. 5 (2015) 12997.DOI: 10.1038/srep12997.
  2. N. Soin, D.Boyer, K.Prashanthi, S.Sharma, A.Narasimum, J.K.Luo, T.Shah, E.Siores and T.Thundat, “Exclusive self-aligned β-phase PVDF films with abnormal piezoelectric constant via phase inversion”, Chem. Comm. 51 (2015) 8257. DOI: 10.1039/c5cc01688f
  3. G.H. Chen,X.R.Zhao, X.Z.Wang, H.Jin, S.J.Li, S.R. Dong,A.J.Flewitt, W.Milne and J.K. Luo, “Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer” Sci. Rep. 5 (2015) 9510. DOI:10.1038/srep09510
  4. W.P. Xuan, X.L.He, J.K.Chen, W.B.Wang, X.Z. Wang, Y.Xu, Z.Xu and J.K. Luo,“High sensitivity flexible Lamb-wave humidity sensor with graphene oxide sensing layer”, nanoscale. 7 (2015) 7430-36. DOI: 10.1039/C5NR00040H
  5. X.L. Bian, X.Z Wang, G.H. Chen, N.N. Hu, X.L. He, S.R. Dong, J.K. Luo, “UV sensing using film bulk acoustic resonators based on Au/n-ZnO/piezoelectric-ZnO/Al structure“, Sci. Rep. 5  (2015) 9123. DOI: 10.1038/srep09123
  6. H.Jin, J.Zhou, X.L.He, W.B. Wang, H.W.Guo,S.R.Dong, D.M. Wang, Y.Xu, J.Geng, J.K.Luo and W.I.Milne; “Flexible surface acoustic wave resonators built on disposable plastic film for electronics and lab-on-a-chip applications”, Sci. Rep. 3 (2013) 2140, DOI: 10.1038/srep02140
  7. L. Garcia-Gancedo, J. Pedros, X.B. Zhao, G.M. Ashley, A.J. Flewitt, W.I. Milne, C.J.B. Ford, J.R. Lu, J.K. Luo, “Dual-mode thin film bulk acoustic wave resonators for parallel sensing of temperature and mass loading”, Biosens. Bioelectron. 38 (2012) 369-74. http://dx.doi.org/10.1016/j.bios.2012.06.023
  8. X.B. Zhao, G.Ashley, L.Garcia-Gancedo, H. Jin, J.K. Luo, A.J. Flewitt, J.R. Lu, “Protein functionalized ZnO Thin Film bulk acoustic resonator as an odorant biosensor”, Sens. Actuat. B163 (2012) 242-46. doi:10.1016/j.snb.2012.01.046
  9. M. Ahmad, J.K. Luo, H. Purnawali, W.M. Huang, P.J. King, P.R Chalker and M. Miraftab; ”Making shape memory polymers reprocessable and reusable by a simple chemical method”, J. Mater. Chem. 20 (2012) 3442-3448. doi: 10.1039/c2jm30489a
  10. M. Ahmad, J.K. Luo and M. Miraftab, “Feasibility study polyurethane Shape Memory Polymer Actuator for pressure bandage applications”, Sci. & Technol. Adv. Mater. 13 (2012) 015006. doi:10.1088/1468-6996/13/1/015006

 

Full list of publications can be found from the links below:

Researchgate: https://www.researchgate.net/profile/Jack_Jikui_Luo
Googlescholar:  http://scholar.google.co.uk/citations?user=089SmCcAAAAJ&hl=en
Scopus: http://www.scopus.com/search/form.url  (search for Luo, J, Bolton)