MEMS is the exotic relatives of semiconductors and integrated circuits (ICs), originally based on silicon wafer production processes but with the dimensions of space, flexion, and constantly varying output akin to analogue devices. Whereas BioMEMS refers to all interfaces and cross-sections of biological sciences and therapeutic disciplines with microsystems and nanotechnology, commercial microfluidic devices rely heavily on material selection and production techniques. Molding, replication, casting, and bonding procedures are being developed that is required for mass production with repeatability and functional dependability at a low cost, better design freedom, and manufacturing ease, which is critical in the medical disposable industry. Nowadays, BioMEMSs are the largest and most diversified applications of MEMS devices. Fabrication processes employed many steps process like wafer selection, lithography, etching, and substrate binding. Furthermore, packaging for safety and biocompatibility is a major problem for the BioMEMS engineer.
TopIntroduction
A miniature machine with combination of mechanical and electrical components is called MEMS (micro-electromechanical system) (Badilescu & Packirisamy, 2016; Folch, 2016). The size of a MEMS device can range from as little as one micrometre, which is considerably less than the width of a single human hair, to as much as several millimetres. MEMS is a term used to refer a class of micro mechatronic devices and their production procedures. Though some MEMS lack any mechanical components, they are nevertheless considered MEMS because they feature membranes, channels, cavities, and springs that are smaller than those found in traditional machinery. Some MEMS devices are also known as transducers because they transform a measured mechanical signal into an electrical or optical signal. In Europe, MEMS is more frequently referred as microsystems technology, whereas micromachines are the more prevalent name for MEMS in Japan is MST (Badilescu & Packirisamy, 2016; Folch, 2016).
Micro-electromechanical systems in the field of biomedicine are commonly referred as “Bio-MEMS”. Lab-on-a-chip (LOC) and micro total analysis systems (µTAS) share many similarities with bio-MEMS and are frequently used interchangeably (Kharisov et al., 2016). The mechanical and microfabrication technologies that are well-suited to use in the life sciences are the primary emphasis of bio-MEMS. However, lab-on-a-chip research focuses on condensing many laboratory procedures and investigations onto a single (often microfluidic) chip. This definition states that lab-on-a-chip devices need not directly serve biological purposes in order to qualify as such. Similar to how micro total analysis systems are typically designed for chemical analysis rather than biological applications, biological uses may not be a primary consideration for these systems. Bio-MEMS may be thought of as a catch-all term for the study and development of microscale devices and systems for use in biological and biomedical research and practise; these devices and systems may or may not involve electrical or mechanical components.
Advancement in Bio-MEMS
The era of bio-MEMS begun with use of vaporized palladium islands as cell adhesion by Carter (1967) (Carter, 1967). Pregnancy test ClearBlue, introduced by Unipath Ltd., became the first microfluidic product to use paper (Olszynko-Gryn, 2017). Widmer and Andreas Manz introduced the term “micro total analysis system” in 1990. Micro total analysis systems were recommended by the study for application in chemical sensing. Miniaturised total chemical-analysis systems (μTAS) was then introduced due to three major reasons (Dempsey et al., 1997). Firstly, before the 1990s, lot of time, money, and expensive equipment were required to perform chromatographic tests, which was a major setback for drug discovery. The Human Genome Project, which began in October 1990, was a further aspect that contributed to advancements in DNA sequencing technology (Watson, 1990). This is very costly that is why capillary electrophoresis (cost effective) is now frequently used to separate DNA and other substances. Thirdly, the Defense Advanced Research Projects Agency of the Department of Defense (US) initiated support for the microfluidic research projects to develop field-deployable microsystems for the identification of biological and chemical agents that could be used by military to encounter terrorist threats. Photolithography tools were used in the microelectronics researchers for microfabrication of micro-electromechanical systems (Fedder, 1994; Maluf & Williams, 2004). MEMS technology was initially created for silicon or glass wafers and utilised solvent-based photoresists, both of which are incompatible with biological material, and therefore, the potential biological uses of this technology were initially limited. In 1993, Kumar and Whitesides revolutionised the bio-MEMS field by developing an relatively cheap method of Polydimethylsiloxane (PDMS) -based microfabrication (Kumar & Whitesides, 1993). The growth of bio-MEMS since then has been phenomenal. The first oligonucleotide chip was invented in 1991. The first solid microneedles for medication delivery were discovered in 1998 and in the same year, polymerase chain reaction chip with continuous flow was created. In 1999, microchannels with heterogeneous laminar flows was used for the selective treatment of cells. Hydrogels like agarose, biocompatible photoresists, and self-assembly are now at the forefront of research for enhancing bio-MEMS as potential alternatives to or supplements to PDMS.