These bots were made for walk­ing: Cells power bio­lo­gic­al machines

Design­ing non-elec­tron­ic bio­lo­gic­al machines has been a riddle that sci­ent­ists at the inter­face of bio­logy and engin­eer­ing have struggled to solve. The walk­ing bio-bots demon­strate the Illinois team’s abil­ity to for­ward-engin­eer func­tion­al machines using only hydro­gel, heart cells and a 3‑D print­er. With an altered design, the bio-bots could be cus­tom­ized for spe­cif­ic applic­a­tions in medi­cine, energy or the envir­on­ment. The research team, led by U. of I. pro­fess­or Rashid Bashir, pub­lished its res­ults in the journ­al Sci­entif­ic Reports. ​“The idea is that, by being able to design with bio­lo­gic­al struc­tures, we can har­ness the power of cells and nature to address chal­lenges facing soci­ety,” said Bashir, an Abel Bliss Pro­fess­or of Engin­eer­ing. ​“As engin­eers, we’ve always built things with hard mater­i­als, mater­i­als that are very pre­dict­able. Yet there are a lot of applic­a­tions where nature solves a prob­lem in such an eleg­ant way. Can we rep­lic­ate some of that if we can under­stand how to put things togeth­er with cells?” The key to the bio-bots’ loco­motion is asym­metry. Resem­bling a tiny spring­board, each bot has one long, thin leg rest­ing on a stout sup­port­ing leg. The thin leg is covered with rat car­di­ac cells. When the heart cells beat, the long leg pulses, pro­pelling the bio-bot for­ward. The team uses a 3‑D print­ing meth­od com­mon in rap­id pro­to­typ­ing to make the main body of the bot from hydro­gel, a soft gelat­in-like poly­mer. This approach allowed the research­ers to explore vari­ous con­form­a­tions and adjust their design for max­im­um speed. The ease of quickly alter­ing design also will allow them to build and test oth­er con­fig­ur­a­tions with an eye toward poten­tial applic­a­tions. For example, Bashir envi­sions the bio-bots being used for drug screen­ing or chem­ic­al ana­lys­is, since the bots’ motion can indic­ate how the cells are respond­ing to the envir­on­ment. By integ­rat­ing cells that respond to cer­tain stim­uli, such as chem­ic­al gradi­ents, the bio-bots could be used as sensors. ​“Our goal is to see if we can get this thing to move toward chem­ic­al gradi­ents, so we could even­tu­ally design some­thing that can look for a spe­cif­ic tox­in and then try to neut­ral­ize it,” said Bashir, who also is a pro­fess­or of elec­tric­al and com­puter engin­eer­ing, and of bioen­gin­eer­ing. ​“Now you can think about a sensor that’s mov­ing and con­stantly sampling and doing some­thing use­ful, in medi­cine and the envir­on­ment. The applic­a­tions could be many, depend­ing on what cell types we use and where we want to go with it.” Next, the team will work to enhance con­trol and func­tion, such as integ­rat­ing neur­ons to dir­ect motion or cells that respond to light. They are also work­ing on cre­at­ing robots of dif­fer­ent shapes, dif­fer­ent num­bers of legs, and robots that could climb slopes or steps. ​“The idea here is that you can do it by for­ward-engin­eer­ing,” said Bashir, who is the dir­ect­or of the Micro and Nan­o­tech­no­logy Labor­at­ory. ​“We have the design rules to make these mil­li­meter-scale shapes and dif­fer­ent phys­ic­al archi­tec­tures, which hasn’t been done with this level of con­trol. What we want to do now is add more func­tion­al­ity to it.” ​“I think we are just begin­ning to scratch the sur­face in this regard,” said gradu­ate stu­dent Vin­cent Chan, first author of the paper. ​“That is what’s so excit­ing about this tech­no­logy – to be able to exploit some of nature’s unique cap­ab­il­it­ies and util­ize it for oth­er bene­fi­cial pur­poses or func­tions.” The Nation­al Sci­ence Found­a­tion sup­por­ted this work through a Sci­ence and Tech­no­logy Cen­ter (Emer­gent Beha­vi­or of Integ­rated Cel­lu­lar Sys­tems). Gradu­ate stu­dent Mitchell Col­lens, postdoc­tor­al research­er Kidong Park, chem­ic­al and bio­lo­gic­al engin­eer­ing pro­fess­or Hyun­joon Kong, and mech­an­ic­al sci­ence and engin­eer­ing pro­fess­or Tah­er Saif were co-authors of the paper. Bashir also is affil­i­ated with the Fre­d­er­ick Seitz Mater­i­als Research Labor­at­ory and the Insti­tute for Gen­om­ic Bio­logy at the U. of I.

Ori­gin­al publication:

Vin­cent Chan, Kidong Park, Mitchell B. Col­lens, Hyun­joon Kong, Tah­er A. Saif, Rashid Bashir. Devel­op­ment of Mini­atur­ized Walk­ing Bio­lo­gic­al Machines. Sci­entif­ic Reports, 2012; 2 DOI: 10.1038/srep00857 Source: Uni­ver­sity of Illinois