A key strength of the HOT platform is that its capabilities can be greatly expanded through software, rather than hardware, upgrade, allowing a wide range of additional experiments to be designed and executed. The instructions sent to the HOT module are simple (x,y,z) trapping beam locations and types, making it straightforward for remote PIs to design new automated routines. For example, remote mixing of a colloidal sample could be initiated by using beams to stir the sample in a preprogrammed pseudorandom pattern. Other functionalities enabled by software alone include 3D imaging of colloids while trapping, automated particle detection and trapping, remote construction of microfluidic valves and pumps from assemblies of trapped particles, and cell elasticity/deformability measurements. In addition, the existence of a space-qualified liquid crystal spatial light modulator (SLM) will enable the development of future SLM-based technologies. An SLM can be used in the imaging train of a microscope to enable simultaneous multifocal brightfield, darkfield, and phase contrast imaging. In addition, SLMs are used in the creation of advanced tractor beams, able to show particle manipulation over tens of cm, with potential applications in remote sampling. SLMs are also a low size, weight, and power solution for steering visible and infrared beams with no moving parts. The prior use of SLMs in the ISS should aid in the development of these and future space-based SLM technologies.
The software and hardware developed for the HOT module in the LMM will be directly usable in other microgravity colloidal experiments, enabled by the growing availability of commercial spaceflight. In addition, these advances will enable progress in colloidal research beyond microgravity. The LMM's underlying commercial Leica hardware will make the HOT module easily adapted for other Leica microscopes, expanding the availability of turnkey spatial light modulator (SLM)-based microscope modules. Applications for SLMs in microscopy include optogenetics for neuroscience research, micromanipulation, 3D imaging, and aberration correction for imaging deep into tissue. To date, the primary users of SLM technology in microscopy have represented the cutting edge of research in new equipment development, using mostly home-built equipment inaccessible to the nonspecialist research community. A current major effort at BNS is to make SLM-based research equipment more robust and user friendly, broadening its availability and usefulness. The advances in software and hardware robustness involved in building a flight-capable platform will benefit these and future developments.